DefinitelyTyped/types/mongoose/index.d.ts

// Type definitions for Mongoose 4.7.1
// Project: http://mongoosejs.com/
// Definitions by: simonxca <https://github.com/simonxca>, horiuchi <https://github.com/horiuchi>, sindrenm <https://github.com/sindrenm>, lukasz-zak <https://github.com/lukasz-zak>
// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
// TypeScript Version: 2.3

/// <reference types="mongodb" />
/// <reference types="node" />


/*
 * Guidelines for maintaining these definitions:
 * - If you spot an error here or there, please submit a PR.
 *   Give some examples/links to documentation if you can.
 *
 * For patches and minor releases:
 * - Browse the changelog at https://github.com/Automattic/mongoose/blob/master/History.md
 *   and make necessary changes. Afterwards, update the version number at the top so we know
 *   which version we are on.
 *
 * For major releases:
 * - Refer to the updated docs at http://mongoosejs.com/docs/api.html
 * - On the left-hand side of the docs is a list of .js files. Reset and update the TODO list below
 *   then go through one-by-one, making any updates to params list, return type, etc. For documentation
 *   changes just copy/paste them into here.
 * - Check the files off as you go. Some files below might not have anything in them. That's ok, this
 *   is just a simple heuristic to keep track of our progress.
 *
 * TODO for version 4.x [updated][tested]:
 * [x][x] index.js
 * [x][x] querystream.js
 * [x][x] connection.js
 * [x][x] utils.js
 * [x][x] browser.js
 * [x][x] drivers/node-mongodb-native/collection.js
 * [x][x] drivers/node-mongodb-native/connection.js
 * [x][x] error/messages.js
 * [x][x] error/validation.js
 * [x][x] error.js
 * [x][x] querycursor.js
 * [x][x] virtualtype.js
 * [x][x] schema.js
 * [x][x] document.js
 * [x][x] types/subdocument.js
 * [x][x] types/array.js
 * [x][x] types/documentarray.js
 * [x][x] types/buffer.js
 * [x][x] types/objectid.js
 * [x][x] types/embedded.js
 * [x][x] query.js
 * [x][x] schema/array.js
 * [x][x] schema/string.js
 * [x][x] schema/documentarray.js
 * [x][x] schema/number.js
 * [x][x] schema/date.js
 * [x][x] schema/buffer.js
 * [x][x] schema/boolean.js
 * [x][x] schema/objectid.js
 * [x][x] schema/mixed.js
 * [x][x] schema/embedded.js
 * [x][x] aggregate.js
 * [x][x] schematype.js
 * [x][x] promise.js
 * [x][x] ES6Promise.js
 * [x][x] model.js
 * [x][x] collection.js
 */

/*
For easier searching, add a header to each section like so:
To find a section, CTRL+F and type "section ___.js"
/*
 * section filename.js
 * http://mongoosejs.com/docs/api.html#filename-js
 */

declare module "mongoose" {
  import events = require('events');
  import mongodb = require('mongodb');
  import stream = require('stream');
  import mongoose = require('mongoose');

  /*
   * Some mongoose classes have the same name as the native JS classes
   * Keep references to native classes using a "Native" prefix
   */
  class NativeBuffer extends global.Buffer {}
  class NativeDate extends global.Date {}
  class NativeError extends global.Error {}

  /*
   * section index.js
   * http://mongoosejs.com/docs/api.html#index-js
   */
  export var DocumentProvider: any;
  // recursive constructor
  export var Mongoose: new(...args: any[]) => typeof mongoose;
  type Mongoose = typeof mongoose;
  export var SchemaTypes: typeof Schema.Types;

  /** Expose connection states for user-land */
  export var STATES: Object;
  /** The default connection of the mongoose module. */
  export var connection: Connection;
  /** The node-mongodb-native driver Mongoose uses. */
  export var mongo: typeof mongodb;
  /** The Mongoose version */
  export var version: string;

  /**
   * Opens the default mongoose connection.
   * Options passed take precedence over options included in connection strings.
   * @returns pseudo-promise wrapper around this
   */
  export function connect(uris: string,
    options?: ConnectionOptions,
    callback?: (err: mongodb.MongoError) => void): MongooseThenable;
  export function connect(uris: string,
    callback?: (err: mongodb.MongoError) => void): MongooseThenable;

  /**
   * Creates a Connection instance.
   * Each connection instance maps to a single database. This method is helpful
   *   when mangaging multiple db connections.
   * @param uri a mongodb:// URI
   * @param options options to pass to the driver
   * @returns the created Connection object
   */
  export function createConnection(): Connection;
  export function createConnection(uri: string,
    options?: ConnectionOptions
  ): Connection;
  export function createConnection(host: string, database_name: string, port?: number,
    options?: ConnectionOptions
  ): Connection;

  /**
   * Disconnects all connections.
   * @param fn called after all connection close.
   * @returns pseudo-promise wrapper around this
   */
  export function disconnect(fn?: (error: any) => void): MongooseThenable;

  /** Gets mongoose options */
  export function get(key: string): any;

  /**
   * Defines a model or retrieves it.
   * Models defined on the mongoose instance are available to all connection
   *   created by the same mongoose instance.
   * @param name model name
   * @param collection (optional, induced from model name)
   * @param skipInit whether to skip initialization (defaults to false)
   */
  export function model<T extends Document>(name: string, schema?: Schema, collection?: string,
    skipInit?: boolean): Model<T>;
  export function model<T extends Document, U extends Model<T>>(
    name: string,
    schema?: Schema,
    collection?: string,
    skipInit?: boolean
  ): U;

  /**
   * Returns an array of model names created on this instance of Mongoose.
   * Does not include names of models created using connection.model().
   */
  export function modelNames(): string[];

  /**
   * Declares a global plugin executed on all Schemas.
   * Equivalent to calling .plugin(fn) on each Schema you create.
   * @param fn plugin callback
   * @param opts optional options
   */
  export function plugin(fn: Function, opts?: Object): typeof mongoose;

  /** Sets mongoose options */
  export function set(key: string, value: any): void;

  type MongooseThenable = typeof mongoose & {
    /**
     * Ability to use mongoose object as a pseudo-promise so .connect().then()
     * and .disconnect().then() are viable.
     */
    then<TRes>(onFulfill?: () => void | TRes | PromiseLike<TRes>,
      onRejected?: (err: mongodb.MongoError) => void | TRes | PromiseLike<TRes>): Promise<TRes>;

    /**
     * Ability to use mongoose object as a pseudo-promise so .connect().then()
     * and .disconnect().then() are viable.
     */
    catch<TRes>(onRejected?: (err: mongodb.MongoError) => void | TRes | PromiseLike<TRes>): Promise<TRes>;
  }

  class CastError extends Error {
    /**
     * The Mongoose CastError constructor
     * @param type The name of the type
     * @param value The value that failed to cast
     * @param path The path a.b.c in the doc where this cast error occurred
     * @param reason The original error that was thrown
     */
    constructor(type: string, value: any, path: string, reason?: NativeError);
  }

  /*
   * section querystream.js
   * http://mongoosejs.com/docs/api.html#querystream-js
   *
   * QueryStream can only be accessed using query#stream(), we only
   *   expose its interface here.
   */
  interface QueryStream extends stream.Stream {
    /**
     * Provides a Node.js 0.8 style ReadStream interface for Queries.
     * @event data emits a single Mongoose document
     * @event error emits when an error occurs during streaming. This will emit before the close event.
     * @event close emits when the stream reaches the end of the cursor or an error occurs, or the stream
     *   is manually destroyed. After this event, no more events are emitted.
     */
    constructor(query: Query<any>, options?: {
      /**
       * optional function which accepts a mongoose document. The return value
       * of the function will be emitted on data.
       */
      transform?: Function;
      [other: string]: any;
    }): QueryStream;

    /**
     * Destroys the stream, closing the underlying cursor, which emits the close event.
     * No more events will be emitted after the close event.
     */
    destroy(err?: NativeError): void;

    /** Pauses this stream. */
    pause(): void;
    /** Pipes this query stream into another stream. This method is inherited from NodeJS Streams. */
    pipe<T extends NodeJS.WritableStream>(destination: T, options?: { end?: boolean; }): T;
    /** Resumes this stream. */
    resume(): void;

    /** Flag stating whether or not this stream is paused. */
    paused: boolean;
    /** Flag stating whether or not this stream is readable. */
    readable: boolean;
  }

  /*
   * section connection.js
   * http://mongoosejs.com/docs/api.html#connection-js
   *
   * The Connection class exposed by require('mongoose')
   *   is actually the driver's NativeConnection class.
   *   connection.js defines a base class that the native
   *   versions extend. See:
   *   http://mongoosejs.com/docs/api.html#drivers-node-mongodb-native-connection-js
   */
  abstract class ConnectionBase extends events.EventEmitter {
    /**
     * For practical reasons, a Connection equals a Db.
     * @param base a mongoose instance
     * @event connecting Emitted when connection.{open,openSet}() is executed on this connection.
     * @event connected Emitted when this connection successfully connects to the db. May be emitted multiple times in reconnected scenarios.
     * @event open Emitted after we connected and onOpen is executed on all of this connections models.
     * @event disconnecting Emitted when connection.close() was executed.
     * @event disconnected Emitted after getting disconnected from the db.
     * @event close Emitted after we disconnected and onClose executed on all of this connections models.
     * @event reconnected Emitted after we connected and subsequently disconnected, followed by successfully another successfull connection.
     * @event error Emitted when an error occurs on this connection.
     * @event fullsetup Emitted in a replica-set scenario, when primary and at least one seconaries specified in the connection string are connected.
     * @event all Emitted in a replica-set scenario, when all nodes specified in the connection string are connected.
     */
    constructor(base: typeof mongoose);

    /**
     * Opens the connection to MongoDB.
     * @param mongodb://uri or the host to which you are connecting
     * @param database database name
     * @param port database port
     * @param options Mongoose forces the db option forceServerObjectId false and cannot be overridden.
     *   Mongoose defaults the server auto_reconnect options to true which can be overridden.
     *   See the node-mongodb-native driver instance for options that it understands.
     *   Options passed take precedence over options included in connection strings.
     */
    open(connection_string: string, database?: string, port?: number,
      options?: ConnectionOpenOptions, callback?: (err: any) => void): any;

    /** Helper for dropDatabase() */
    dropDatabase(callback?: (err: any) => void): Promise<void>;

    /**
     * Opens the connection to a replica set.
     * @param uris comma-separated mongodb:// URIs
     * @param database database name if not included in uris
     * @param options passed to the internal driver
     */
    openSet(uris: string, database?: string, options?: ConnectionOpenSetOptions,
      callback?: (err: any) => void): any;

    /** Closes the connection */
    close(callback?: (err: any) => void): Promise<void>;

    /**
     * Retrieves a collection, creating it if not cached.
     * Not typically needed by applications. Just talk to your collection through your model.
     * @param name name of the collection
     * @param options optional collection options
     */
    collection(name: string, options?: Object): Collection;

    /**
     * Defines or retrieves a model.
     * When no collection argument is passed, Mongoose produces a collection name by passing
     * the model name to the utils.toCollectionName method. This method pluralizes the name.
     * If you don't like this behavior, either pass a collection name or set your schemas
     * collection name option.
     * @param name the model name
     * @param schema a schema. necessary when defining a model
     * @param collection name of mongodb collection (optional) if not given it will be induced from model name
     * @returns The compiled model
     */
    model<T extends Document>(name: string, schema?: Schema, collection?: string): Model<T>;
    model<T extends Document, U extends Model<T>>(
      name: string,
      schema?: Schema,
      collection?: string
    ): U;

    /** Returns an array of model names created on this connection. */
    modelNames(): string[];

    /** A hash of the global options that are associated with this connection */
    config: Object;

    /** The mongodb.Db instance, set when the connection is opened */
    db: mongodb.Db;

    /** A hash of the collections associated with this connection */
    collections: { [index: string]: Collection };

    /**
     * Connection ready state
     * 0 = disconnected
     * 1 = connected
     * 2 = connecting
     * 3 = disconnecting
     * Each state change emits its associated event name.
     */
    readyState: number;
  }

  interface ConnectionOptionsBase {
    /** passed to the connection db instance */
    db?: any;
    /** passed to the connection server instance(s) */
    server?: any;
    /** passed to the connection ReplSet instance */
    replset?: any;
    /** username for authentication */
    user?: string;
    /** password for authentication */
    pass?: string;
    /** options for authentication (see http://mongodb.github.com/node-mongodb-native/api-generated/db.html#authenticate) */
    auth?: any;
  }

  /** See the node-mongodb-native driver instance for options that it understands. */
  interface ConnectionOpenOptions extends ConnectionOptionsBase {
    /** mongoose-specific options */
    config?: {
      /**
       * set to false to disable automatic index creation for all
       * models associated with this connection.
       */
      autoIndex?: boolean;
    };
  }

  /** See the node-mongodb-native driver instance for options that it understands. */
  interface ConnectionOpenSetOptions extends ConnectionOptionsBase {
    /**
     * If true, enables High Availability support for mongos
     * If connecting to multiple mongos servers, set the mongos option to true.
     */
    mongos?: boolean;

    /** sets the underlying driver's promise library (see http://mongodb.github.io/node-mongodb-native/2.1/api/MongoClient.html) */
    promiseLibrary?: any;

    /** See http://mongoosejs.com/docs/connections.html#use-mongo-client **/
    useMongoClient?: boolean;
  }

  interface ConnectionOptions extends
    ConnectionOpenOptions,
    ConnectionOpenSetOptions {}

  /*
   * section drivers/node-mongodb-native/collection.js
   * http://mongoosejs.com/docs/api.html#drivers-node-mongodb-native-collection-js
   */
  var Collection: Collection;
  interface Collection extends CollectionBase {
    /**
     * Collection constructor
     * @param name name of the collection
     * @param conn A MongooseConnection instance
     * @param opts optional collection options
     */
    new(name: string, conn: Connection, opts?: Object): Collection;
    /** Formatter for debug print args */
    $format(arg: any): string;
    /** Debug print helper */
    $print(name: any, i: any, args: any[]): void;
    /** Retreives information about this collections indexes. */
    getIndexes(): any;
  }

  /*
   * section drivers/node-mongodb-native/connection.js
   * http://mongoosejs.com/docs/api.html#drivers-node-mongodb-native-connection-js
   */
  class Connection extends ConnectionBase {
    /**
     * Switches to a different database using the same connection pool.
     * @param name The database name
     * @returns New Connection Object
     */
    useDb(name: string): Connection;

    /** Expose the possible connection states. */
    static STATES: Object;
  }

  /*
   * section error/validation.js
   * http://mongoosejs.com/docs/api.html#error-validation-js
   */
  class ValidationError extends Error {
    /** Console.log helper */
    toString(): string;
  }

  /*
   * section error.js
   * http://mongoosejs.com/docs/api.html#error-js
   */
  class Error extends global.Error {
    /**
     * MongooseError constructor
     * @param msg Error message
     */
    constructor(msg: string);

    /**
     * The default built-in validator error messages. These may be customized.
     * As you might have noticed, error messages support basic templating
     * {PATH} is replaced with the invalid document path
     * {VALUE} is replaced with the invalid value
     * {TYPE} is replaced with the validator type such as "regexp", "min", or "user defined"
     * {MIN} is replaced with the declared min value for the Number.min validator
     * {MAX} is replaced with the declared max value for the Number.max validator
     */
    static messages: Object;

    /** For backwards compatibility. Same as mongoose.Error.messages */
    static Messages: Object;
  }

  /*
   * section querycursor.js
   * http://mongoosejs.com/docs/api.html#querycursor-js
   *
   * Callback signatures are from: http://mongodb.github.io/node-mongodb-native/2.1/api/Cursor.html#close
   * QueryCursor can only be accessed by query#cursor(), we only
   *   expose its interface to enable type-checking.
   */
  interface QueryCursor<T extends Document> extends stream.Readable {
    /**
     * A QueryCursor is a concurrency primitive for processing query results
     * one document at a time. A QueryCursor fulfills the Node.js streams3 API,
     * in addition to several other mechanisms for loading documents from MongoDB
     * one at a time.
     * Unless you're an advanced user, do not instantiate this class directly.
     * Use Query#cursor() instead.
     * @param options query options passed to .find()
     * @event cursor Emitted when the cursor is created
     * @event error Emitted when an error occurred
     * @event data Emitted when the stream is flowing and the next doc is ready
     * @event end Emitted when the stream is exhausted
     */
    constructor(query: Query<T>, options: Object): QueryCursor<T>;

    /** Marks this cursor as closed. Will stop streaming and subsequent calls to next() will error. */
    close(callback?: (error: any, result: any) => void): Promise<any>;

    /**
     * Execute fn for every document in the cursor. If fn returns a promise,
     * will wait for the promise to resolve before iterating on to the next one.
     * Returns a promise that resolves when done.
     * @param callback executed when all docs have been processed
     */
    eachAsync(fn: (doc: T) => any, callback?: (err: any) => void): Promise<T>;

    /**
     * Registers a transform function which subsequently maps documents retrieved
     * via the streams interface or .next()
     */
    map(fn: (doc: T) => T): this;

    /**
     * Get the next document from this cursor. Will return null when there are
     * no documents left.
     */
    next(callback?: (err: any, doc?: T) => void): Promise<any>;
  }

  /*
   * section virtualtype.js
   * http://mongoosejs.com/docs/api.html#virtualtype-js
   */
  class VirtualType {
    /** This is what mongoose uses to define virtual attributes via Schema.prototype.virtual. */
    constructor(options: Object, name: string);
    /** Applies getters to value using optional scope. */
    applyGetters(value: Object, scope: Object): any;
    /** Applies setters to value using optional scope. */
    applySetters(value: Object, scope: Object): any;
    /** Defines a getter. */
    get(fn: Function): this;
    /** Defines a setter. */
    set(fn: Function): this;
  }

  /*
   * section schema.js
   * http://mongoosejs.com/docs/api.html#schema-js
   */
  class Schema extends events.EventEmitter {
    /**
     * Schema constructor.
     * When nesting schemas, (children in the example above), always declare
     * the child schema first before passing it into its parent.
     * @event init Emitted after the schema is compiled into a Model.
     */
    constructor(definition?: SchemaDefinition, options?: SchemaOptions);

    /** Adds key path / schema type pairs to this schema. */
    add(obj: SchemaDefinition, prefix?: string): void;

    /**
     * Iterates the schemas paths similar to Array.forEach.
     * @param fn callback function
     * @returns this
     */
    eachPath(fn: (path: string, type: SchemaType) => void): this;

    /**
     * Gets a schema option.
     * @param key option name
     */
    get(key: string): any;

    /**
     * Defines an index (most likely compound) for this schema.
     * @param options Options to pass to MongoDB driver's createIndex() function
     * @param options.expires Mongoose-specific syntactic sugar, uses ms to convert
     *   expires option into seconds for the expireAfterSeconds in the above link.
     */
    index(fields: Object, options?: {
      expires?: string;
      [other: string]: any;
    }): this;

    /** Compiles indexes from fields and schema-level indexes */
    indexes(): any[];

    /**
     * Loads an ES6 class into a schema. Maps setters + getters, static methods, and
     * instance methods to schema virtuals, statics, and methods.
     */
    loadClass(model: Function): this;

    /**
     * Adds an instance method to documents constructed from Models compiled from this schema.
     * If a hash of name/fn pairs is passed as the only argument, each name/fn pair will be added as methods.
     */
    method(method: string, fn: Function): this;
    method(methodObj: { [name: string]: Function }): this;

    /**
     * Gets/sets schema paths.
     * Sets a path (if arity 2)
     * Gets a path (if arity 1)
     */
    path(path: string): SchemaType;
    path(path: string, constructor: any): this;

    /**
     * Returns the pathType of path for this schema.
     * @returns whether it is a real, virtual, nested, or ad-hoc/undefined path.
     */
    pathType(path: string): string;

    /**
     * Registers a plugin for this schema.
     * @param plugin callback
     */
    plugin(plugin: (schema: Schema, options?: Object) => void, opts?: Object): this;

    /**
     * Defines a post hook for the document
     * Post hooks fire on the event emitted from document instances of Models compiled
     *   from this schema.
     * @param method name of the method to hook
     * @param fn callback
     */
    post<T extends Document>(method: string, fn: (
      error: mongodb.MongoError, doc: T, next: (err?: NativeError) => void
    ) => void): this;

    post<T extends Document>(method: string, fn: (
      doc: T, next: (err?: NativeError) => void
    ) => void): this;

    /**
     * Defines a pre hook for the document.
     */
    pre(method: string, parallel: boolean, fn: (next: (err?: NativeError) => void, done: (err?: NativeError) => void) => void,
      errorCb?: (err: Error) => void): this;
    pre(method: string, fn: (next: (err?: NativeError) => void) => void,
      errorCb?: (err: Error) => void): this;

    /**
     * Adds a method call to the queue.
     * @param name name of the document method to call later
     * @param args arguments to pass to the method
     */
    queue(name: string, args: any[]): this;

    /**
     * Removes the given path (or [paths]).
     */
    remove(path: string | string[]): void;

    /**
     * @param invalidate refresh the cache
     * @returns an Array of path strings that are required by this schema.
     */
    requiredPaths(invalidate?: boolean): string[];

    /**
     * Sets/gets a schema option.
     * @param key option name
     * @param value if not passed, the current option value is returned
     */
    set(key: string): any;
    set(key: string, value: any): this;

    /**
     * Adds static "class" methods to Models compiled from this schema.
     */
    static(name: string, fn: Function): this;
    static(nameObj: { [name: string]: Function }): this;

    /** Creates a virtual type with the given name. */
    virtual(name: string, options?: Object): VirtualType;

    /** Returns the virtual type with the given name. */
    virtualpath(name: string): VirtualType;

    /** The allowed index types */
    static indexTypes: string[];

    /**
     * Reserved document keys.
     * Keys in this object are names that are rejected in schema declarations
     * b/c they conflict with mongoose functionality. Using these key name
     * will throw an error.
     */
    static reserved: Object;

    /** Object of currently defined methods on this schema. */
    methods: any;
    /** Object of currently defined statics on this schema. */
    statics: any;
    /** The original object passed to the schema constructor */
    obj: any;
  }

  interface SchemaOptions {
    /** defaults to null (which means use the connection's autoIndex option) */
    autoIndex?: boolean;
    /** defaults to true */
    bufferCommands?: boolean;
    /** defaults to false */
    capped?: boolean | number | { size?: number; max?: number; autoIndexId?: boolean; };
    /** no default */
    collection?: string;
    /** defaults to "__t" */
    discriminatorKey?: string;
    /** defaults to false. */
    emitIndexErrors?: boolean;
    /** defaults to true */
    id?: boolean;
    /** defaults to true */
    _id?: boolean;
    /** controls document#toObject behavior when called manually - defaults to true */
    minimize?: boolean;
    read?: string;
    /** defaults to true. */
    safe?: boolean;
    /** defaults to null */
    shardKey?: boolean;
    /** defaults to true */
    strict?: boolean;
    /** no default */
    toJSON?: Object;
    /** no default */
    toObject?: Object;
    /** defaults to 'type' */
    typeKey?: string;
    /** defaults to false */
    useNestedStrict?: boolean;
    /** defaults to true */
    validateBeforeSave?: boolean;
    /** defaults to "__v" */
    versionKey?: string|boolean;
    /** defaults to false */
    retainKeyOrder?: boolean;
    /**
     * skipVersioning allows excluding paths from
     * versioning (the internal revision will not be
     * incremented even if these paths are updated).
     */
    skipVersioning?: Object;
    /**
     * If set timestamps, mongoose assigns createdAt
     * and updatedAt fields to your schema, the type
     * assigned is Date.
     */
    timestamps?: Object;
  }

  /*
   * Intellisense for Schema definitions
   */
  interface SchemaDefinition {
    [path: string]: SchemaTypeOpts<any>;
  }

  /*
   * The standard options available when configuring a schema type:
   * new Schema({
   *   name: {
   *     type: String,
   *     required: true,
   *     ...
   *   }
   * });
   *
   * Note: the properties have Object as a fallback type: | Object
   *   because this interface does not apply to a schematype that
   *   does not have a type property. Ex:
   * new Schema({
   *   name: {
   *     first: String,    // since name does not have a "type" property
   *     last: String      //   first and last can have any valid type
   *     ...
   *   }
   * });
   *
   * References:
   * - http://mongoosejs.com/docs/schematypes.html
   * - http://mongoosejs.com/docs/api.html#schema_Schema.Types
   */
  interface SchemaTypeOpts<T> {
    /* Common Options for all schema types */
    type?: T;

    /** Sets a default value for this SchemaType. */
    default?: SchemaTypeOpts.DefaultFn<T> | T;

    /**
     * Getters allow you to transform the representation of the data as it travels
     * from the raw mongodb document to the value that you see.
     */
    get?: (value: T, schematype?: this) => T | Object;

    /** Declares the index options for this schematype. */
    index?: SchemaTypeOpts.IndexOpts | boolean | string;

    /**
     * Adds a required validator to this SchemaType. The validator gets added
     * to the front of this SchemaType's validators array using unshift().
     */
    required?: SchemaTypeOpts.RequiredFn<T> |
      boolean | [boolean, string] |
      string | [string, string] |
      Object;

    /**
     * Sets default select() behavior for this path.
     * Set to true if this path should always be included in the results, false
     * if it should be excluded by default. This setting can be overridden at
     * the query level.
     */
    select?: boolean | Object;

    /**
     * Setters allow you to transform the data before it gets to the raw mongodb
     * document and is set as a value on an actual key.
     */
    set?: (value: T, schematype?: this) => T | Object;

    /** Declares a sparse index. */
    sparse?: boolean | Object;

    /** Declares a full text index. */
    text?: boolean | Object;

    /**
     * Adds validator(s) for this document path.
     * Validators always receive the value to validate as their first argument
     * and must return Boolean. Returning false means validation failed.
     */
    validate?: RegExp | [RegExp, string] |
      SchemaTypeOpts.ValidateFn<T> | [SchemaTypeOpts.ValidateFn<T>, string] |
      SchemaTypeOpts.ValidateOpts | SchemaTypeOpts.ValidateOpts[] |
      Object;

    /** Declares an unique index. */
    unique?: boolean | Object;


    /* Options for specific schema types (String, Number, Date, etc.) */
    /** String only - Adds an enum validator */
    enum?: T[] | SchemaTypeOpts.EnumOpts<T> | Object;
    /** String only - Adds a lowercase setter. */
    lowercase?: boolean | Object;
    /** String only - Sets a regexp validator. */
    match?: RegExp | [RegExp, string] | Object;
    /** String only - Sets a maximum length validator. */
    maxlength?: number | [number, string] | Object;
    /** String only - Sets a minimum length validator. */
    minlength?: number | [number, string] | Object;
    /** String only - Adds a trim setter. */
    trim?: boolean | Object;
    /** String only - Adds an uppercase setter. */
    uppercase?: boolean | Object;

    /**
     * Date, Number only - Sets a minimum number validator.
     * Sets a minimum date validator.
     */
    min?: number | [number, string] |
      Date | [Date, string] |
      Object;

    /**
     * Date, Number only - Sets a maximum number validator.
     * Sets a maximum date validator.
     */
    max?: number | [number, string] |
      Date | [Date, string] |
      Object;

    /**
     * Date only - Declares a TTL index (rounded to the nearest second)
     * for Date types only.
     */
    expires?: number | string | Object;

    /** ObjectId only - Adds an auto-generated ObjectId default if turnOn is true. */
    auto?: boolean | Object;

    [other: string]: any;
  }

  // Interfaces specific to schema type options should be scoped in this namespace
  namespace SchemaTypeOpts {
    interface DefaultFn<T> {
      (...args: any[]): T;
    }

    interface RequiredFn<T> {
      (required: boolean, message?: string): T;
    }

    interface ValidateFn<T> {
      (obj: RegExp | Function, message?: string, type?: string): T;
    }

    interface ValidateOpts {
      validator?: RegExp | Function,
      msg?: string,
      type?: string
    }

    interface EnumOpts<T> {
      values?: T[];
      message?: string;
    }

    interface IndexOpts {
      background?: boolean,
      expires?: number | string
      sparse?: boolean,
      type?: string,
      unique?: boolean,
    }
  }

  /*
   * section document.js
   * http://mongoosejs.com/docs/api.html#document-js
   */
  interface MongooseDocument extends MongooseDocumentOptionals { }
  class MongooseDocument {
    /** Checks if a path is set to its default. */
    $isDefault(path?: string): boolean;

    /**
     * Takes a populated field and returns it to its unpopulated state.
     * If the path was not populated, this is a no-op.
     */
    depopulate(path: string): void;

    /**
     * Returns true if the Document stores the same data as doc.
     * Documents are considered equal when they have matching _ids, unless neither document
     * has an _id, in which case this function falls back to usin deepEqual().
     * @param doc a document to compare
     */
    equals(doc: MongooseDocument): boolean;

    /**
     * Explicitly executes population and returns a promise.
     * Useful for ES2015 integration.
     * @returns promise that resolves to the document when population is done
     */
    execPopulate(): Promise<this>;

    /**
     * Returns the value of a path.
     * @param type optionally specify a type for on-the-fly attributes
     */
    get(path: string, type?: any): any;

    /**
     * Initializes the document without setters or marking anything modified.
     * Called internally after a document is returned from mongodb.
     * @param doc document returned by mongo
     * @param fn callback
     */
    init(doc: MongooseDocument, fn?: () => void): this;
    init(doc: MongooseDocument, opts: Object, fn?: () => void): this;

    /** Helper for console.log */
    inspect(options?: Object): any;

    /**
     * Marks a path as invalid, causing validation to fail.
     * The errorMsg argument will become the message of the ValidationError.
     * The value argument (if passed) will be available through the ValidationError.value property.
     * @param path the field to invalidate
     * @param errorMsg the error which states the reason path was invalid
     * @param value optional invalid value
     * @param kind optional kind property for the error
     * @returns the current ValidationError, with all currently invalidated paths
     */
    invalidate(path: string, errorMsg: string | NativeError, value: any, kind?: string): ValidationError | boolean;

    /** Returns true if path was directly set and modified, else false. */
    isDirectModified(path: string): boolean;

    /** Checks if path was initialized */
    isInit(path: string): boolean;

    /**
     * Returns true if this document was modified, else false.
     * If path is given, checks if a path or any full path containing path as part of its path
     * chain has been modified.
     */
    isModified(path?: string): boolean;

    /** Checks if path was selected in the source query which initialized this document. */
    isSelected(path: string): boolean;

    /**
     * Marks the path as having pending changes to write to the db.
     * Very helpful when using Mixed types.
     * @param path the path to mark modified
     */
    markModified(path: string): void;

    /** Returns the list of paths that have been modified. */
    modifiedPaths(): string[];

    /**
     * Populates document references, executing the callback when complete.
     * If you want to use promises instead, use this function with
     * execPopulate()
     * Population does not occur unless a callback is passed or you explicitly
     * call execPopulate(). Passing the same path a second time will overwrite
     * the previous path options. See Model.populate() for explaination of options.
     * @param path The path to populate or an options object
     * @param names The properties to fetch from the populated document
     * @param callback When passed, population is invoked
     */
    populate(callback: (err: any, res: this) => void): this;
    populate(path: string, callback?: (err: any, res: this) => void): this;
    populate(path: string, names: string, callback?: (err: any, res: this) => void): this;
    populate(options: ModelPopulateOptions | ModelPopulateOptions[], callback?: (err: any, res: this) => void): this;

    /** Gets _id(s) used during population of the given path. If the path was not populated, undefined is returned. */
    populated(path: string): any;

    /**
     * Sets the value of a path, or many paths.
     * @param path path or object of key/vals to set
     * @param val the value to set
     * @param type optionally specify a type for "on-the-fly" attributes
     * @param options optionally specify options that modify the behavior of the set
     */
    set(path: string, val: any, options?: Object): this;
    set(path: string, val: any, type: any, options?: Object): this;
    set(value: Object): this;

    /**
     * The return value of this method is used in calls to JSON.stringify(doc).
     * This method accepts the same options as Document#toObject. To apply the
     * options to every document of your schema by default, set your schemas
     * toJSON option to the same argument.
     */
    toJSON(options?: DocumentToObjectOptions): Object;

    /**
     * Converts this document into a plain javascript object, ready for storage in MongoDB.
     * Buffers are converted to instances of mongodb.Binary for proper storage.
     */
    toObject(options?: DocumentToObjectOptions): Object;

    /** Helper for console.log */
    toString(): string;

    /**
     * Clears the modified state on the specified path.
     * @param path the path to unmark modified
     */
    unmarkModified(path: string): void;

    /** Sends an update command with this document _id as the query selector.  */
    update(doc: Object, callback?: (err: any, raw: any) => void): Query<any>;
    update(doc: Object, options: ModelUpdateOptions,
      callback?: (err: any, raw: any) => void): Query<any>;

    /**
     * Executes registered validation rules for this document.
     * @param optional options internal options
     * @param callback callback called after validation completes, passing an error if one occurred
     */
    validate(callback?: (err: any) => void): Promise<void>;
    validate(optional: Object, callback?: (err: any) => void): Promise<void>;

    /**
     * Executes registered validation rules (skipping asynchronous validators) for this document.
     * This method is useful if you need synchronous validation.
     * @param pathsToValidate only validate the given paths
     * @returns MongooseError if there are errors during validation, or undefined if there is no error.
     */
    validateSync(pathsToValidate?: string | string[]): Error;

    /** Hash containing current validation errors. */
    errors: Object;
    /** This documents _id. */
    _id: any;
    /** Boolean flag specifying if the document is new. */
    isNew: boolean;
    /** The documents schema. */
    schema: Schema;
  }

  interface MongooseDocumentOptionals {
    /** The string version of this documents _id. */
    id?: string;
  }

  interface DocumentToObjectOptions {
    /** apply all getters (path and virtual getters) */
    getters?: boolean;
    /** apply virtual getters (can override getters option) */
    virtuals?: boolean;
    /** remove empty objects (defaults to true) */
    minimize?: boolean;
    /**
     * A transform function to apply to the resulting document before returning
     * @param doc The mongoose document which is being converted
     * @param ret The plain object representation which has been converted
     * @param options The options in use (either schema options or the options passed inline)
     */
    transform?: (doc: any, ret: Object, options: Object) => any;
    /** depopulate any populated paths, replacing them with their original refs (defaults to false) */
    depopulate?: boolean;
    /** whether to include the version key (defaults to true) */
    versionKey?: boolean;
    /**
     * keep the order of object keys. If this is set to true,
     * Object.keys(new Doc({ a: 1, b: 2}).toObject()) will
     * always produce ['a', 'b'] (defaults to false)
     */
    retainKeyOrder?: boolean;
  }

  namespace Types {
    /*
      * section types/subdocument.js
      * http://mongoosejs.com/docs/api.html#types-subdocument-js
      */
    class Subdocument extends MongooseDocument {
      /** Returns the top level document of this sub-document. */
      ownerDocument(): MongooseDocument;

      /**
       * Null-out this subdoc
       * @param callback optional callback for compatibility with Document.prototype.remove
       */
      remove(callback?: (err: any) => void): void;
      remove(options: Object, callback?: (err: any) => void): void;
    }

    /*
     * section types/array.js
     * http://mongoosejs.com/docs/api.html#types-array-js
     */
    class Array<T> extends global.Array<T> {
      /**
       * Atomically shifts the array at most one time per document save().
       * Calling this mulitple times on an array before saving sends the same command as
       * calling it once. This update is implemented using the MongoDB $pop method which
       * enforces this restriction.
       */
      $shift(): T;

      /** Alias of pull */
      remove(...args: any[]): this;

      /**
       * Pops the array atomically at most one time per document save().
       * Calling this mulitple times on an array before saving sends the same command as
       * calling it once. This update is implemented using the MongoDB $pop method which
       * enforces this restriction.
       */
      $pop(): T;

      /**
       * Adds values to the array if not already present.
       * @returns the values that were added
       */
      addToSet(...args: any[]): T[];

      /**
       * Return the index of obj or -1 if not found.
       * @param obj he item to look for
       */
      indexOf(obj: any): number;

      /** Helper for console.log */
      inspect(): any;

      /**
       * Marks the entire array as modified, which if saved, will store it as a $set
       * operation, potentially overwritting any changes that happen between when you
       * retrieved the object and when you save it.
       * @returns new length of the array
       */
      nonAtomicPush(...args: any[]): number;

      /**
       * Wraps Array#pop with proper change tracking.
       * marks the entire array as modified which will pass the entire thing to $set
       * potentially overwritting any changes that happen between when you retrieved
       * the object and when you save it.
       */
      pop(): T;

      /**
       * Pulls items from the array atomically. Equality is determined by casting
       * the provided value to an embedded document and comparing using
       * the Document.equals() function.
       */
      pull(...args: any[]): this;

      /**
       * Wraps Array#push with proper change tracking.
       * @returns new length of the array
       */
      push(...args: any[]): number;

      /** Sets the casted val at index i and marks the array modified. */
      set(i: number, val: any): this;

      /**
       * Wraps Array#shift with proper change tracking.
       * Marks the entire array as modified, which if saved, will store it as a $set operation,
       * potentially overwritting any changes that happen between when you retrieved the object
       * and when you save it.
       */
      shift(): T;

      /**
       * Wraps Array#sort with proper change tracking.
       * Marks the entire array as modified, which if saved, will store it as a $set operation,
       * potentially overwritting any changes that happen between when you retrieved the object
       * and when you save it.
       */
      // some lib.d.ts have return type "this" and others have return type "T[]"
      // which causes errors. Let the inherited array provide the sort() method.
      //sort(compareFn?: (a: T, b: T) => number): T[];

      /**
       * Wraps Array#splice with proper change tracking and casting.
       * Marks the entire array as modified, which if saved, will store it as a $set operation,
       * potentially overwritting any changes that happen between when you retrieved the object
       * and when you save it.
       */
      splice(...args: any[]): T[];

      /** Returns a native js Array. */
      toObject(options?: Object): T[];

      /**
       * Wraps Array#unshift with proper change tracking.
       * Marks the entire array as modified, which if saved, will store it as a $set operation,
       * potentially overwritting any changes that happen between when you retrieved the object
       * and when you save it.
       */
      unshift(...args: any[]): number;
    }

    /*
      * section types/documentarray.js
      * http://mongoosejs.com/docs/api.html#types-documentarray-js
      */
    class DocumentArray<T extends MongooseDocument> extends Types.Array<T> {
      /**
       * Creates a subdocument casted to this schema.
       * This is the same subdocument constructor used for casting.
       * @param obj the value to cast to this arrays SubDocument schema
       */
      create(obj: Object): T;

      /**
       * Searches array items for the first document with a matching _id.
       * @returns the subdocument or null if not found.
       */
      id(id: ObjectId | string | number | NativeBuffer): T;

      /** Helper for console.log */
      inspect(): T[];

      /**
       * Returns a native js Array of plain js objects
       * @param options optional options to pass to each documents toObject
       *   method call during conversion
       */
      toObject(options?: Object): T[];
    }

    /*
     * section types/buffer.js
     * http://mongoosejs.com/docs/api.html#types-buffer-js
     */
    class Buffer extends global.Buffer {
      /**
       * Copies the buffer.
       * Buffer#copy does not mark target as modified so you must copy
       * from a MongooseBuffer for it to work as expected. This is a
       * work around since copy modifies the target, not this.
       */
      copy(target: NativeBuffer, ...nodeBufferArgs: any[]): number;

      /** Determines if this buffer is equals to other buffer */
      equals(other: NativeBuffer): boolean;

      /** Sets the subtype option and marks the buffer modified. */
      subtype(subtype: number): void;

      /** Converts this buffer to its Binary type representation. */
      toObject(subtype?: number): mongodb.Binary;

      /** Writes the buffer. */
      write(string: string, ...nodeBufferArgs: any[]): number;
    }

    /*
      * section types/objectid.js
      * http://mongoosejs.com/docs/api.html#types-objectid-js
      */
    var ObjectId: ObjectIdConstructor;

    // mongodb.ObjectID does not allow mongoose.Types.ObjectId(id). This is
    //   commonly used in mongoose and is found in an example in the docs:
    //   http://mongoosejs.com/docs/api.html#aggregate_Aggregate
    // constructor exposes static methods of mongodb.ObjectID and ObjectId(id)
    type ObjectIdConstructor = typeof mongodb.ObjectID & {
      (s?: string | number): mongodb.ObjectID;
    };

    // var objectId: mongoose.Types.ObjectId should reference mongodb.ObjectID not
    //   the ObjectIdConstructor, so we add the interface below
    interface ObjectId extends mongodb.ObjectID {}

    class Decimal128 extends mongodb.Decimal128 {}

    /*
      * section types/embedded.js
      * http://mongoosejs.com/docs/api.html#types-embedded-js
      */
    class Embedded extends MongooseDocument {
      /** Helper for console.log */
      inspect(): Object;

      /**
       * Marks a path as invalid, causing validation to fail.
       * @param path the field to invalidate
       * @param err error which states the reason path was invalid
       */
      invalidate(path: string, err: string | NativeError): boolean;

      /** Returns the top level document of this sub-document. */
      ownerDocument(): MongooseDocument;
      /** Returns this sub-documents parent document. */
      parent(): MongooseDocument;
      /** Returns this sub-documents parent array. */
      parentArray(): DocumentArray<MongooseDocument>;

      /** Removes the subdocument from its parent array. */
      remove(options?: {
        noop?: boolean;
      }, fn?: (err: any) => void): this;

      /**
       * Marks the embedded doc modified.
       * @param path the path which changed
       */
      markModified(path: string): void;
    }
  }

  /*
   * section query.js
   * http://mongoosejs.com/docs/api.html#query-js
   *
   * Query<T> is for backwards compatibility. Example: Query<T>.find() returns Query<T[]>.
   * If later in the query chain a method returns Query<T>, we will need to know type T.
   * So we save this type as the second type parameter in DocumentQuery. Since people have
   * been using Query<T>, we set it as an alias of DocumentQuery.
   */
  class Query<T> extends DocumentQuery<T, any> {}
  class DocumentQuery<T, DocType extends Document> extends mquery {
    /**
     * Specifies a javascript function or expression to pass to MongoDBs query system.
     * Only use $where when you have a condition that cannot be met using other MongoDB
     * operators like $lt. Be sure to read about all of its caveats before using.
     * @param js javascript string or function
     */
    $where(js: string | Function): this;

    /**
     * Specifies an $all query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    all(val: number): this;
    all(path: string, val: number): this;

    /**
     * Specifies arguments for a $and condition.
     * @param array array of conditions
     */
    and(array: Object[]): this;

    /** Specifies the batchSize option. Cannot be used with distinct() */
    batchSize(val: number): this;

    /**
     * Specifies a $box condition
     * @param Upper Right Coords
     */
    box(val: Object): this;
    box(lower: number[], upper: number[]): this;

    /** Casts this query to the schema of model, If obj is present, it is cast instead of this query.*/
    cast(model: any, obj?: Object): Object;

    /**
     * Executes the query returning a Promise which will be
     * resolved with either the doc(s) or rejected with the error.
     * Like .then(), but only takes a rejection handler.
     */
    catch<TRes>(reject?: (err: any) => void | TRes | PromiseLike<TRes>): Promise<TRes>;

    /**
     * DEPRECATED Alias for circle
     * Specifies a $center or $centerSphere condition.
     * @deprecated Use circle instead.
     */
    center(area: Object): this;
    center(path: string, area: Object): this;

    /**
     * DEPRECATED Specifies a $centerSphere condition
     * @deprecated Use circle instead.
     */
    centerSphere(path: string, val: Object): this;
    centerSphere(val: Object): this;

    /** Specifies a $center or $centerSphere condition. */
    circle(area: Object): this;
    circle(path: string, area: Object): this;

    /** Adds a collation to this op (MongoDB 3.4 and up) */
    collation(value: CollationOptions): this;

    /** Specifies the comment option. Cannot be used with distinct() */
    comment(val: string): this;

    /**
     * Specifying this query as a count query. Passing a callback executes the query.
     * @param criteria mongodb selector
     */
    count(callback?: (err: any, count: number) => void): Query<number>;
    count(criteria: Object, callback?: (err: any, count: number) => void): Query<number>;

    /**
     * Returns a wrapper around a mongodb driver cursor. A Query<T>Cursor exposes a
     * Streams3-compatible interface, as well as a .next() function.
     */
    cursor(options?: Object): QueryCursor<DocType>;

    /** Declares or executes a distict() operation. Passing a callback executes the query. */
    distinct(callback?: (err: any, res: any[]) => void): Query<any[]>;
    distinct(field: string, callback?: (err: any, res: any[]) => void): Query<any[]>;
    distinct(field: string, criteria: Object | Query<any>,
      callback?: (err: any, res: any[]) => void): Query<any[]>;

    /** Specifies an $elemMatch condition */
    elemMatch(criteria: (elem: Query<any>) => void): this;
    elemMatch(criteria: Object): this;
    elemMatch(path: string | Object | Function, criteria: (elem: Query<any>) => void): this;
    elemMatch(path: string | Object | Function, criteria: Object): this;

    /** Specifies the complementary comparison value for paths specified with where() */
    equals(val: Object): this;

    /** Executes the query */
    exec(callback?: (err: any, res: T) => void): Promise<T>;
    exec(operation: string | Function, callback?: (err: any, res: T) => void): Promise<T>;

    /** Specifies an $exists condition */
    exists(val?: boolean): this;
    exists(path: string, val?: boolean): this;

    /**
     * Finds documents. When no callback is passed, the query is not executed. When the
     * query is executed, the result will be an array of documents.
     * @param criteria mongodb selector
     */
    find(callback?: (err: any, res: DocType[]) => void): DocumentQuery<DocType[], DocType>;
    find(criteria: Object,
      callback?: (err: any, res: DocType[]) => void): DocumentQuery<DocType[], DocType>;

    /**
     * Declares the query a findOne operation. When executed, the first found document is
     * passed to the callback. Passing a callback executes the query. The result of the query
     * is a single document.
     * @param criteria mongodb selector
     * @param projection optional fields to return
     */
    findOne(callback?: (err: any, res: DocType | null) => void): DocumentQuery<DocType | null, DocType>;
    findOne(criteria: Object,
      callback?: (err: any, res: DocType | null) => void): DocumentQuery<DocType | null, DocType>;

    /**
     * Issues a mongodb findAndModify remove command.
     * Finds a matching document, removes it, passing the found document (if any) to the
     * callback. Executes immediately if callback is passed.
     */
    findOneAndRemove(callback?: (error: any, doc: DocType | null, result: any) => void): DocumentQuery<DocType | null, DocType>;
    findOneAndRemove(conditions: Object,
      callback?: (error: any, doc: DocType | null, result: any) => void): DocumentQuery<DocType | null, DocType>;
    findOneAndRemove(conditions: Object, options: QueryFindOneAndRemoveOptions,
      callback?: (error: any, doc: DocType | null, result: any) => void): DocumentQuery<DocType | null, DocType>;

    /**
     * Issues a mongodb findAndModify update command.
     * Finds a matching document, updates it according to the update arg, passing any options, and returns
     * the found document (if any) to the callback. The query executes immediately if callback is passed.
     */
    findOneAndUpdate(callback?: (err: any, doc: DocType | null) => void): DocumentQuery<DocType | null, DocType>;
    findOneAndUpdate(update: Object,
      callback?: (err: any, doc: DocType | null, res: any) => void): DocumentQuery<DocType | null, DocType>;
    findOneAndUpdate(query: Object | Query<any>, update: Object,
      callback?: (err: any, doc: DocType | null, res: any) => void): DocumentQuery<DocType | null, DocType>;
    findOneAndUpdate(query: Object | Query<any>, update: Object, options: QueryFindOneAndUpdateOptions,
      callback?: (err: any, doc: DocType | null, res: any) => void): DocumentQuery<DocType | null, DocType>;

    /**
     * Specifies a $geometry condition. geometry() must come after either intersects() or within().
     * @param object Must contain a type property which is a String and a coordinates property which
     *   is an Array. See the examples.
     */
    geometry(object: { type: string, coordinates: any[] }): this;

    /**
     * Returns the current query conditions as a JSON object.
     * @returns current query conditions
     */
    getQuery(): any;

    /**
     * Returns the current update operations as a JSON object.
     * @returns current update operations
     */
    getUpdate(): any;

    /**
     * Specifies a $gt query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    gt(val: number): this;
    gt(path: string, val: number): this;

    /**
     * Specifies a $gte query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    gte(val: number): this;
    gte(path: string, val: number): this;

    /**
     * Sets query hints.
     * @param val a hint object
     */
    hint(val: Object): this;

    /**
     * Specifies an $in query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    in(val: any[]): this;
    in(path: string, val: any[]): this;

    /** Declares an intersects query for geometry(). MUST be used after where(). */
    intersects(arg?: Object): this;

    /**
     * Sets the lean option.
     * Documents returned from queries with the lean option enabled are plain
     * javascript objects, not MongooseDocuments. They have no save method,
     * getters/setters or other Mongoose magic applied.
     * @param bool defaults to true
     */
    lean(bool?: boolean): Query<Object>;

    /** Specifies the maximum number of documents the query will return. Cannot be used with distinct() */
    limit(val: number): this;

    /**
     * Specifies a $lt query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    lt(val: number): this;
    lt(path: string, val: number): this;

    /**
     * Specifies a $lte query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    lte(val: number): this;
    lte(path: string, val: number): this;

    /**
     * Specifies a $maxDistance query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    maxDistance(val: number): this;
    maxDistance(path: string, val: number): this;

    /** @deprecated Alias of maxScan */
    maxscan(val: number): this;
    /** Specifies the maxScan option. Cannot be used with distinct() */
    maxScan(val: number): this;

    /**
     * Merges another Query or conditions object into this one.
     * When a Query is passed, conditions, field selection and options are merged.
     */
    merge(source: Object | Query<any>): this;

    /** Specifies a $mod condition */
    mod(val: number[]): this;
    mod(path: string, val: number[]): this;

    /**
     * Specifies a $ne query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    ne(val: any): this;
    ne(path: string, val: any): this;

    /** Specifies a $near or $nearSphere condition. */
    near(val: Object): this;
    near(path: string, val: Object): this;

    /**
     * DEPRECATED Specifies a $nearSphere condition
     * @deprecated Use query.near() instead with the spherical option set to true.
     */
    nearSphere(val: Object): this;
    nearSphere(path: string, val: Object): this;

    /**
     * Specifies a $nin query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    nin(val: any[]): this;
    nin(path: string, val: any[]): this;

    /**
     * Specifies arguments for a $nor condition.
     * @param array array of conditions
     */
    nor(array: Object[]): this;

    /**
     * Specifies arguments for an $or condition.
     * @param array array of conditions
     */
    or(array: Object[]): this;

    /** Specifies a $polygon condition */
    polygon(...coordinatePairs: number[][]): this;
    polygon(path: string, ...coordinatePairs: number[][]): this;

    /**
     * Specifies paths which should be populated with other documents.
     * Paths are populated after the query executes and a response is received. A separate
     * query is then executed for each path specified for population. After a response for
     * each query has also been returned, the results are passed to the callback.
     * @param path either the path to populate or an object specifying all parameters
     * @param select Field selection for the population query
     * @param model The model you wish to use for population. If not specified, populate
     *   will look up the model by the name in the Schema's ref field.
     * @param match Conditions for the population query
     * @param options Options for the population query (sort, etc)
     */
    populate(path: string | Object, select?: string | Object, model?: any,
      match?: Object, options?: Object): this;
    populate(options: ModelPopulateOptions | ModelPopulateOptions[]): this;

    /**
     * Determines the MongoDB nodes from which to read.
     * @param pref one of the listed preference options or aliases
     * @tags optional tags for this query
     */
    read(pref: string, tags?: Object[]): this;

    /**
     * Specifies a $regex query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    regex(val: RegExp): this;
    regex(path: string, val: RegExp): this;

    /**
     * Declare and/or execute this query as a remove() operation.
     * The operation is only executed when a callback is passed. To force execution without a callback,
     * you must first call remove() and then execute it by using the exec() method.
     * @param criteria mongodb selector
     */
    remove(callback?: (err: any) => void): Query<mongodb.WriteOpResult>;
    remove(criteria: Object | Query<any>, callback?: (err: any) => void): Query<mongodb.WriteOpResult>;

    /** Specifies which document fields to include or exclude (also known as the query "projection") */
    select(arg: string | Object): this;
    /** Determines if field selection has been made. */
    selected(): boolean;
    /** Determines if exclusive field selection has been made.*/
    selectedExclusively(): boolean;
    /** Determines if inclusive field selection has been made. */
    selectedInclusively(): boolean;
    /** Sets query options. */
    setOptions(options: Object): this;

    /**
     * Specifies a $size query condition.
     * When called with one argument, the most recent path passed to where() is used.
     */
    size(val: number): this;
    size(path: string, val: number): this;

    /** Specifies the number of documents to skip. Cannot be used with distinct() */
    skip(val: number): this;

    /**
     * DEPRECATED Sets the slaveOk option.
     * @param v defaults to true
     * @deprecated in MongoDB 2.2 in favor of read preferences.
     */
    slaveOk(v?: boolean): this;

    /**
     * Specifies a $slice projection for an array.
     * @param val number/range of elements to slice
     */
    slice(val: number | number[]): this;
    slice(path: string, val: number | number[]): this;

    /** Specifies this query as a snapshot query. Cannot be used with distinct() */
    snapshot(v?: boolean): this;

    /**
     * Sets the sort order
     * If an object is passed, values allowed are asc, desc, ascending, descending, 1, and -1.
     * If a string is passed, it must be a space delimited list of path names. The
     * sort order of each path is ascending unless the path name is prefixed with -
     * which will be treated as descending.
     */
    sort(arg: string | Object): this;

    /** Returns a Node.js 0.8 style read stream interface. */
    stream(options?: { transform?: Function; }): QueryStream;

    /**
     * Sets the tailable option (for use with capped collections). Cannot be used with distinct()
     * @param bool defaults to true
     * @param opts options to set
     * @param opts.numberOfRetries if cursor is exhausted, retry this many times before giving up
     * @param opts.tailableRetryInterval if cursor is exhausted, wait this many milliseconds before retrying
     */
    tailable(bool?: boolean, opts?: {
      numberOfRetries?: number;
      tailableRetryInterval?: number;
    }): this;

    /** Executes this query and returns a promise */
    then<TRes>(resolve?: (res: T) => void | TRes | PromiseLike<TRes>,
      reject?: (err: any) =>  void | TRes | PromiseLike<TRes>): Promise<TRes>;

    /**
     * Converts this query to a customized, reusable query
     * constructor with all arguments and options retained.
     */
    toConstructor<T>(): new(...args: any[]) => Query<T>;
    toConstructor<T, Doc extends Document>(): new(...args: any[]) => DocumentQuery<T, Doc>;

    /**
     * Declare and/or execute this query as an update() operation.
     * All paths passed that are not $atomic operations will become $set ops.
     * @param doc the update command
     */
    update(callback?: (err: any, affectedRows: number) => void): Query<number>;
    update(doc: Object, callback?: (err: any, affectedRows: number) => void): Query<number>;
    update(criteria: Object, doc: Object,
      callback?: (err: any, affectedRows: number) => void): Query<number>;
    update(criteria: Object, doc: Object, options: QueryUpdateOptions,
      callback?: (err: any, affectedRows: number) => void): Query<number>;

    /** Specifies a path for use with chaining. */
    where(path?: string | Object, val?: any): this;

    /** Defines a $within or $geoWithin argument for geo-spatial queries. */
    within(val?: Object): this;
    within(coordinate: number[], ...coordinatePairs: number[][]): this;

    /** Flag to opt out of using $geoWithin. */
    static use$geoWithin: boolean;
  }

  // https://github.com/aheckmann/mquery
  // mquery currently does not have a type definition please
  //   replace it if one is ever created
  class mquery {}

  interface QueryFindOneAndRemoveOptions {
    /** if multiple docs are found by the conditions, sets the sort order to choose which doc to update */
    sort?: any;
    /** puts a time limit on the query - requires mongodb >= 2.6.0 */
    maxTimeMS?: number;
    /** if true, passes the raw result from the MongoDB driver as the third callback parameter */
    passRawResult?: boolean;
  }

  interface QueryFindOneAndUpdateOptions extends QueryFindOneAndRemoveOptions {
    /** if true, return the modified document rather than the original. defaults to false (changed in 4.0) */
    new?: boolean;
    /** creates the object if it doesn't exist. defaults to false. */
    upsert?: boolean;
    /** Field selection. Equivalent to .select(fields).findOneAndUpdate() */
    fields?: Object | string;
    /** if true, runs update validators on this command. Update validators validate the update operation against the model's schema. */
    runValidators?: boolean;
    /**
     * if this and upsert are true, mongoose will apply the defaults specified in the model's schema if a new document
     * is created. This option only works on MongoDB >= 2.4 because it relies on MongoDB's $setOnInsert operator.
     */
    setDefaultsOnInsert?: boolean;
    /**
     * if set to 'query' and runValidators is on, this will refer to the query in custom validator
     * functions that update validation runs. Does nothing if runValidators is false.
     */
    context?: string;
  }

  interface QueryUpdateOptions extends ModelUpdateOptions {
    /**
     * if set to 'query' and runValidators is on, this will refer to the query
     * in customvalidator functions that update validation runs. Does nothing
     * if runValidators is false.
     */
    context?: string;
  }

  interface CollationOptions {
    locale?: string;
    caseLevel?: boolean;
    caseFirst?: string;
    strength?: number;
    numericOrdering?: boolean;
    alternate?: string;
    maxVariable?: string;
    backwards?: boolean;
  }

  namespace Schema {
    namespace Types {
      /*
        * section schema/array.js
        * http://mongoosejs.com/docs/api.html#schema-array-js
        */
      class Array extends SchemaType {
        /** Array SchemaType constructor */
        constructor(key: string, cast?: SchemaType, options?: Object);

        /**
         * Check if the given value satisfies a required validator. The given value
         * must be not null nor undefined, and have a non-zero length.
         */
        checkRequired<T extends { length: number }>(value: T): boolean;

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;
      }

      /*
        * section schema/string.js
        * http://mongoosejs.com/docs/api.html#schema-string-js
        */
      class String extends SchemaType {
        /** String SchemaType constructor. */
        constructor(key: string, options?: Object);

        /** Check if the given value satisfies a required validator. */
        checkRequired(value: any, doc: MongooseDocument): boolean;

        /**
         * Adds an enum validator
         * @param args enumeration values
         */
        enum(args: string | string[] | Object): this;

        /** Adds a lowercase setter. */
        lowercase(): this;

        /**
         * Sets a regexp validator. Any value that does not pass regExp.test(val) will fail validation.
         * @param regExp regular expression to test against
         * @param message optional custom error message
         */
        match(regExp: RegExp, message?: string): this;

        /**
         * Sets a maximum length validator.
         * @param value maximum string length
         * @param message optional custom error message
         */
        maxlength(value: number, message?: string): this;

        /**
         * Sets a minimum length validator.
         * @param value minimum string length
         * @param message optional custom error message
         */
        minlength(value: number, message?: string): this;

        /** Adds a trim setter. The string value will be trimmed when set. */
        trim(): this;
        /** Adds an uppercase setter. */
        uppercase(): this;

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;

      }

      /*
        * section schema/documentarray.js
        * http://mongoosejs.com/docs/api.html#schema-documentarray-js
        */
      class DocumentArray extends Array {
        /** SubdocsArray SchemaType constructor */
        constructor(key: string, schema: Schema, options?: Object);

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;
      }

      /*
        * section schema/number.js
        * http://mongoosejs.com/docs/api.html#schema-number-js
        */
      class Number extends SchemaType {
        /** Number SchemaType constructor. */
        constructor(key: string, options?: Object);

        /** Check if the given value satisfies a required validator. */
        checkRequired(value: any, doc: MongooseDocument): boolean;

        /**
         * Sets a maximum number validator.
         * @param maximum number
         * @param message optional custom error message
         */
        max(maximum: number, message?: string): this;

        /**
         * Sets a minimum number validator.
         * @param value minimum number
         * @param message optional custom error message
         */
        min(value: number, message?: string): this;

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;
      }

      /*
        * section schema/date.js
        * http://mongoosejs.com/docs/api.html#schema-date-js
        */
      class Date extends SchemaType {
        /** Date SchemaType constructor. */
        constructor(key: string, options?: Object);

        /**
         * Check if the given value satisfies a required validator. To satisfy
         * a required validator, the given value must be an instance of Date.
         */
        checkRequired(value: any, doc: MongooseDocument): boolean;

        /** Declares a TTL index (rounded to the nearest second) for Date types only. */
        expires(when: number | string): this;

        /**
         * Sets a maximum date validator.
         * @param maximum date
         * @param message optional custom error message
         */
        max(maximum: NativeDate, message?: string): this;

        /**
         * Sets a minimum date validator.
         * @param value minimum date
         * @param message optional custom error message
         */
        min(value: NativeDate, message?: string): this;

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;
      }

      /*
        * section schema/buffer.js
        * http://mongoosejs.com/docs/api.html#schema-buffer-js
        */
      class Buffer extends SchemaType {
        /** Buffer SchemaType constructor */
        constructor(key: string, options?: Object);

        /**
         * Check if the given value satisfies a required validator. To satisfy a
         * required validator, a buffer must not be null or undefined and have
         * non-zero length.
         */
        checkRequired(value: any, doc: MongooseDocument): boolean;

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;

      }

      /*
        * section schema/boolean.js
        * http://mongoosejs.com/docs/api.html#schema-boolean-js
        */
      class Boolean extends SchemaType {
        /** Boolean SchemaType constructor. */
        constructor(path: string, options?: Object);

        /**
         * Check if the given value satisfies a required validator. For a
         * boolean to satisfy a required validator, it must be strictly
         * equal to true or to false.
         */
        checkRequired(value: any): boolean;

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;
      }

      /*
        * section schema/objectid.js
        * http://mongoosejs.com/docs/api.html#schema-objectid-js
        */
      class ObjectId extends SchemaType {
        /** ObjectId SchemaType constructor. */
        constructor(key: string, options?: Object);

        /**
         * Adds an auto-generated ObjectId default if turnOn is true.
         * @param turnOn auto generated ObjectId defaults
         */
        auto(turnOn: boolean): this;

        /** Check if the given value satisfies a required validator. */
        checkRequired(value: any, doc: MongooseDocument): boolean;

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;
      }
      /*
        * section schema/decimal128.js
        * http://mongoosejs.com/docs/api.html#schema-decimal128-js
        */
      class Decimal128 extends SchemaType {
        /** Decimal128 SchemaType constructor. */
        constructor(key: string, options?: Object);

        /** Check if the given value satisfies a required validator. */
        checkRequired(value: any, doc: MongooseDocument): boolean;

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;
      }

      /*
        * section schema/mixed.js
        * http://mongoosejs.com/docs/api.html#schema-mixed-js
        */
      class Mixed extends SchemaType {
        /** Mixed SchemaType constructor. */
        constructor(path: string, options?: Object);

        /** This schema type's name, to defend against minifiers that mangle function names. */
        static schemaName: string;
      }

      /*
        * section schema/embedded.js
        * http://mongoosejs.com/docs/api.html#schema-embedded-js
        */
      class Embedded extends SchemaType {
        /** Sub-schema schematype constructor */
        constructor(schema: Schema, key: string, options?: Object);
      }
    }
  }

  /*
   * section aggregate.js
   * http://mongoosejs.com/docs/api.html#aggregate-js
   */
  class Aggregate<T> {
    /**
     * Aggregate constructor used for building aggregation pipelines.
     * Returned when calling Model.aggregate().
     * @param ops aggregation operator(s) or operator array
     */
    constructor(ops?: Object | any[], ...args: any[]);

    /** Adds a cursor flag */
    addCursorFlag(flag: string, value: boolean): this;

    /**
     * Sets the allowDiskUse option for the aggregation query (ignored for < 2.6.0)
     * @param value Should tell server it can use hard drive to store data during aggregation.
     * @param tags optional tags for this query
     */
    allowDiskUse(value: boolean, tags?: any[]): this;

    /**
     * Appends new operators to this aggregate pipeline
     * @param ops operator(s) to append
     */
    append(...ops: Object[]): this;

    /** Adds a collation. */
    collation(options: CollationOptions): this;

    /**
     * Sets the cursor option option for the aggregation query (ignored for < 2.6.0).
     * Note the different syntax below: .exec() returns a cursor object, and no callback
     * is necessary.
     * @param options set the cursor batch size
     */
    cursor(options: Object): this;

    // If cursor option is on, could return an object
    /** Executes the aggregate pipeline on the currently bound Model. */
    exec(callback?: (err: any, result: T) => void): Promise<T> | any;

    /** Execute the aggregation with explain */
    explain(callback?: (err: any, result: T) => void): Promise<T>;

    /**
     * Appends a new custom $group operator to this aggregate pipeline.
     * @param arg $group operator contents
     */
    group(arg: Object): this;

    /**
     * Appends a new $limit operator to this aggregate pipeline.
     * @param num maximum number of records to pass to the next stage
     */
    limit(num: number): this;

    /**
     * Appends new custom $lookup operator(s) to this aggregate pipeline.
     * @param options to $lookup as described in the above link
     */
    lookup(options: Object): this;

    /**
     * Appends a new custom $match operator to this aggregate pipeline.
     * @param arg $match operator contents
     */
    match(arg: Object): this;

    /**
     * Binds this aggregate to a model.
     * @param model the model to which the aggregate is to be bound
     */
    model(model: any): this;

    /**
     * Appends a new $geoNear operator to this aggregate pipeline.
     * MUST be used as the first operator in the pipeline.
     */
    near(parameters: Object): this;

    /**
     * Appends a new $project operator to this aggregate pipeline.
     * Mongoose query selection syntax is also supported.
     * @param arg field specification
     */
    project(arg: string | Object): this;

    /**
     * Sets the readPreference option for the aggregation query.
     * @param pref one of the listed preference options or their aliases
     * @param tags optional tags for this query
     */
    read(pref: string, tags?: Object[]): this;

    /**
     * Appends new custom $sample operator(s) to this aggregate pipeline.
     * @param size number of random documents to pick
     */
    sample(size: number): this;

    /**
     * Appends a new $skip operator to this aggregate pipeline.
     * @param num number of records to skip before next stage
     */
    skip(num: number): this;

    /**
     * Appends a new $sort operator to this aggregate pipeline.
     * If an object is passed, values allowed are asc, desc, ascending, descending, 1, and -1.
     * If a string is passed, it must be a space delimited list of path names. The sort order
     * of each path is ascending unless the path name is prefixed with - which will be treated
     * as descending.
     */
    sort(arg: string | Object): this;

    /** Provides promise for aggregate. */
    then<TRes>(resolve?: (val: T) =>  void | TRes | PromiseLike<TRes>,
      reject?: (err: any) =>  void | TRes | PromiseLike<TRes>): Promise<TRes>;

    /**
     * Appends new custom $unwind operator(s) to this aggregate pipeline.
     * Note that the $unwind operator requires the path name to start with '$'.
     * Mongoose will prepend '$' if the specified field doesn't start '$'.
     * @param fields the field(s) to unwind
     */
    unwind(...fields: string[]): this;
    /**
     * Appends new custom $unwind operator(s) to this aggregate pipeline
     * new in mongodb 3.2
     */
    unwind(...opts: { path: string, includeArrayIndex?: string, preserveNullAndEmptyArrays?: boolean }[]): this;
  }

  /*
   * section schematype.js
   * http://mongoosejs.com/docs/api.html#schematype-js
   */
  class SchemaType {
    /** SchemaType constructor */
    constructor(path: string, options?: Object, instance?: string);

    /**
     * Sets a default value for this SchemaType.
     * Defaults can be either functions which return the value to use as the
     * default or the literal value itself. Either way, the value will be cast
     * based on its schema type before being set during document creation.
     * @param val the default value
     */
    default(val: any): any;

    /** Adds a getter to this schematype. */
    get(fn: Function): this;

    /**
     * Declares the index options for this schematype.
     * Indexes are created in the background by default. Specify background: false to override.
     */
    index(options: Object | boolean | string): this;

    /**
     * Adds a required validator to this SchemaType. The validator gets added
     * to the front of this SchemaType's validators array using unshift().
     * @param required enable/disable the validator
     * @param message optional custom error message
     */
    required(required: boolean, message?: string): this;

    /** Sets default select() behavior for this path. */
    select(val: boolean): this;
    /** Adds a setter to this schematype. */
    set(fn: Function): this;
    /** Declares a sparse index. */
    sparse(bool: boolean): this;
    /** Declares a full text index. */
    text(bool: boolean): this;
    /** Declares an unique index. */
    unique(bool: boolean): this;

    /**
     * Adds validator(s) for this document path.
     * Validators always receive the value to validate as their first argument
     * and must return Boolean. Returning false means validation failed.
     * @param obj validator
     * @param errorMsg optional error message
     * @param type optional validator type
     */
    validate(obj: RegExp | Function | Object, errorMsg?: string,
      type?: string): this;
  }

  /*
   * section promise.js
   * http://mongoosejs.com/docs/api.html#promise-js
   */
  /**
   * To assign your own promise library:
   *
   * 1. Typescript does not allow assigning properties of imported modules.
   *    To avoid compile errors use one of the options below in your code:
   *
   *    - (<any>mongoose).Promise = YOUR_PROMISE;
   *    - require('mongoose').Promise = YOUR_PROMISE;
   *    - import mongoose = require('mongoose');
   *      mongoose.Promise = YOUR_PROMISE;
   *
   * 2. To assign type definitions for your promise library, you will need
   *    to have a .d.ts file with the following code when you compile:
   *
   *    - import * as Q from 'q';
   *      declare module 'mongoose' {
   *        type Promise<T> = Q.promise<T>;
   *      }
   *
   *    - import * as Bluebird from 'bluebird';
   *      declare module 'mongoose' {
   *        type Promise<T> = Bluebird<T>;
   *      }
   *
   * Uses global.Promise by default. If you would like to use mongoose default
   *   mpromise implementation (which is deprecated), you can omit step 1 and
   *   run npm install @types/mongoose-promise
   */
  export var Promise: any;
  export var PromiseProvider: any;

  /*
   * section model.js
   * http://mongoosejs.com/docs/api.html#model-js
   */
  export var Model: Model<any>;
  interface Model<T extends Document> extends NodeJS.EventEmitter, ModelProperties {
    /**
     * Model constructor
     * Provides the interface to MongoDB collections as well as creates document instances.
     * @param doc values with which to create the document
     * @event error If listening to this event, it is emitted when a document
     *   was saved without passing a callback and an error occurred. If not
     *   listening, the event bubbles to the connection used to create this Model.
     * @event index Emitted after Model#ensureIndexes completes. If an error
     *   occurred it is passed with the event.
     * @event index-single-start Emitted when an individual index starts within
     *   Model#ensureIndexes. The fields and options being used to build the index
     *   are also passed with the event.
     * @event index-single-done Emitted when an individual index finishes within
     *   Model#ensureIndexes. If an error occurred it is passed with the event.
     *   The fields, options, and index name are also passed.
     */
    new(doc?: Object): T;

    /**
     * Finds a single document by its _id field. findById(id) is almost*
     * equivalent to findOne({ _id: id }). findById() triggers findOne hooks.
     * @param id value of _id to query by
     * @param projection optional fields to return
     */
    findById(id: Object | string | number,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;
    findById(id: Object | string | number, projection: Object,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;
    findById(id: Object | string | number, projection: Object, options: Object,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;

    model(name: string): Model<T>;

    /**
     * Creates a Query and specifies a $where condition.
     * @param argument is a javascript string or anonymous function
     */
    $where(argument: string | Function): DocumentQuery<T, T>;

    /**
     * Performs aggregations on the models collection.
     * If a callback is passed, the aggregate is executed and a Promise is returned.
     * If a callback is not passed, the aggregate itself is returned.
     * @param ... aggregation pipeline operator(s) or operator array
     */
    aggregate(...aggregations: Object[]): Aggregate<Object[]>;
    aggregate(...aggregationsWithCallback: Object[]): Promise<Object[]>;

    /** Counts number of matching documents in a database collection. */
    count(conditions: Object, callback?: (err: any, count: number) => void): Query<number>;

    /**
     * Shortcut for saving one or more documents to the database. MyModel.create(docs)
     * does new MyModel(doc).save() for every doc in docs.
     * Triggers the save() hook.
     */
    create(docs: any[], callback?: (err: any, res: T[]) => void): Promise<T[]>;
    create(...docs: Object[]): Promise<T>;
    create(...docsWithCallback: Object[]): Promise<T>;

    /**
     * Adds a discriminator type.
     * @param name discriminator model name
     * @param schema discriminator model schema
     */
    discriminator<U extends Document>(name: string, schema: Schema): Model<U>;

    /** Creates a Query for a distinct operation. Passing a callback immediately executes the query. */
    distinct(field: string, callback?: (err: any, res: any[]) => void): Query<any[]>;
    distinct(field: string, conditions: Object,
      callback?: (err: any, res: any[]) => void): Query<any[]>;

    /**
     * Sends ensureIndex commands to mongo for each index declared in the schema.
     * @param options internal options
     * @param cb optional callback
     */
    ensureIndexes(callback?: (err: any) => void): Promise<void>;
    ensureIndexes(options: Object, callback?: (err: any) => void): Promise<void>;

    /**
     * Finds documents.
     * @param projection optional fields to return
     */
    find(callback?: (err: any, res: T[]) => void): DocumentQuery<T[], T>;
    find(conditions: Object, callback?: (err: any, res: T[]) => void): DocumentQuery<T[], T>;
    find(conditions: Object, projection?: Object | null,
      callback?: (err: any, res: T[]) => void): DocumentQuery<T[], T>;
    find(conditions: Object, projection?: Object | null, options?: Object | null,
      callback?: (err: any, res: T[]) => void): DocumentQuery<T[], T>;



    /**
     * Issue a mongodb findAndModify remove command by a document's _id field.
     * findByIdAndRemove(id, ...) is equivalent to findOneAndRemove({ _id: id }, ...).
     * Finds a matching document, removes it, passing the found document (if any) to the callback.
     * Executes immediately if callback is passed, else a Query object is returned.
     * @param id value of _id to query by
     */
    findByIdAndRemove(): DocumentQuery<T | null, T>;
    findByIdAndRemove(id: Object | number | string,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;
    findByIdAndRemove(id: Object | number | string, options: {
      /** if multiple docs are found by the conditions, sets the sort order to choose which doc to update */
      sort?: Object;
      /** sets the document fields to return */
      select?: Object;
    }, callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;

    /**
     * Issues a mongodb findAndModify update command by a document's _id field. findByIdAndUpdate(id, ...)
     * is equivalent to findOneAndUpdate({ _id: id }, ...).
     * @param id value of _id to query by
     */
    findByIdAndUpdate(): DocumentQuery<T | null, T>;
    findByIdAndUpdate(id: Object | number | string, update: Object,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;
    findByIdAndUpdate(id: Object | number | string, update: Object,
      options: ModelFindByIdAndUpdateOptions,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;

    /**
     * Finds one document.
     * The conditions are cast to their respective SchemaTypes before the command is sent.
     * @param projection optional fields to return
     */
    findOne(conditions?: Object,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;
    findOne(conditions: Object, projection: Object,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;
    findOne(conditions: Object, projection: Object, options: Object,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;

    /**
     * Issue a mongodb findAndModify remove command.
     * Finds a matching document, removes it, passing the found document (if any) to the callback.
     * Executes immediately if callback is passed else a Query object is returned.
     */
    findOneAndRemove(): DocumentQuery<T | null, T>;
    findOneAndRemove(conditions: Object,
      callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;
    findOneAndRemove(conditions: Object, options: {
      /**
       * if multiple docs are found by the conditions, sets the sort order to choose
       * which doc to update
       */
      sort?: Object;
      /** puts a time limit on the query - requires mongodb >= 2.6.0 */
      maxTimeMS?: number;
      /** sets the document fields to return */
      select?: Object;
    }, callback?: (err: any, res: T | null) => void): DocumentQuery<T | null, T>;

    /**
     * Issues a mongodb findAndModify update command.
     * Finds a matching document, updates it according to the update arg, passing any options,
     * and returns the found document (if any) to the callback. The query executes immediately
     * if callback is passed else a Query object is returned.
     */
    findOneAndUpdate(): DocumentQuery<T | null, T>;
    findOneAndUpdate(conditions: Object, update: Object,
      callback?: (err: any, doc: T | null, res: any) => void): DocumentQuery<T | null, T>;
    findOneAndUpdate(conditions: Object, update: Object,
      options: ModelFindOneAndUpdateOptions,
      callback?: (err: any, doc: T | null, res: any) => void): DocumentQuery<T | null, T>;

    /**
     * geoNear support for Mongoose
     * @param GeoJSON point or legacy coordinate pair [x,y] to search near
     * @param options for the qurery
     * @param callback optional callback for the query
     */
    geoNear(point: number[] | {
      type: string;
      coordinates: number[]
    }, options: {
      /** return the raw object */
      lean?: boolean;
      [other: string]: any;
    }, callback?: (err: any, res: T[], stats: any) => void): DocumentQuery<T[], T>;

    /**
     * Implements $geoSearch functionality for Mongoose
     * @param conditions an object that specifies the match condition (required)
     * @param options for the geoSearch, some (near, maxDistance) are required
     * @param callback optional callback
     */
    geoSearch(conditions: Object, options: {
      /** x,y point to search for */
      near: number[];
      /** the maximum distance from the point near that a result can be */
      maxDistance: number;
      /** The maximum number of results to return */
      limit?: number;
      /** return the raw object instead of the Mongoose Model */
      lean?: boolean;
    }, callback?: (err: any, res: T[]) => void): DocumentQuery<T[], T>;

    /**
     * Shortcut for creating a new Document from existing raw data,
     * pre-saved in the DB. The document returned has no paths marked
     * as modified initially.
     */
    hydrate(obj: Object): T;

    /**
     * Shortcut for validating an array of documents and inserting them into
     * MongoDB if they're all valid. This function is faster than .create()
     * because it only sends one operation to the server, rather than one for each
     * document.
     * This function does not trigger save middleware.
     */
    insertMany(docs: any[], callback?: (error: any, docs: T[]) => void): Promise<T[]>;
    insertMany(doc: any, callback?: (error: any, doc: T) => void): Promise<T>;
    insertMany(...docsWithCallback: Object[]): Promise<T>;

    /**
     * Executes a mapReduce command.
     * @param o an object specifying map-reduce options
     * @param callbackoptional callback
     */
    mapReduce<Key, Value>(
      o: ModelMapReduceOption<T, Key, Value>,
      callback?: (err: any, res: any) => void
    ): Promise<any>;

    /**
     * Populates document references.
     * @param docs Either a single document or array of documents to populate.
     * @param options A hash of key/val (path, options) used for population.
     * @param callback Optional callback, executed upon completion. Receives err and the doc(s).
     */
    populate(docs: Object[], options: ModelPopulateOptions | ModelPopulateOptions[],
      callback?: (err: any, res: T[]) => void): Promise<T[]>;
    populate<T>(docs: Object, options: ModelPopulateOptions | ModelPopulateOptions[],
      callback?: (err: any, res: T) => void): Promise<T>;

    /** Removes documents from the collection. */
    remove(conditions: Object, callback?: (err: any) => void): Query<void>;

    /**
     * Updates documents in the database without returning them.
     * All update values are cast to their appropriate SchemaTypes before being sent.
     */
    update(conditions: Object, doc: Object,
      callback?: (err: any, raw: any) => void): Query<any>;
    update(conditions: Object, doc: Object, options: ModelUpdateOptions,
      callback?: (err: any, raw: any) => void): Query<any>;

    /** Creates a Query, applies the passed conditions, and returns the Query. */
    where(path: string, val?: Object): Query<any>;
  }

  interface Document extends MongooseDocument, NodeJS.EventEmitter, ModelProperties {
    /** Signal that we desire an increment of this documents version. */
    increment(): this;

    /**
     * Returns another Model instance.
     * @param name model name
     */
    model(name: string): Model<this>;

    /**
     * Removes this document from the db.
     * @param fn optional callback
     */
    remove(fn?: (err: any, product: this) => void): Promise<this>;

    /**
     * Saves this document.
     * @param options options optional options
     * @param options.safe overrides schema's safe option
     * @param options.validateBeforeSave set to false to save without validating.
     * @param fn optional callback
     */
    save(options?: SaveOptions, fn?: (err: any, product: this, numAffected: number) => void): Promise<this>;
    save(fn?: (err: any, product: this, numAffected: number) => void): Promise<this>;

    /**
     * Version using default version key. See http://mongoosejs.com/docs/guide.html#versionKey
     * If you're using another key, you will have to access it using []: doc[_myVersionKey]
     */
    __v?: number;
  }

  interface SaveOptions {
    safe?: boolean | WriteConcern;
    validateBeforeSave?: boolean;
  }

  interface WriteConcern {
    j?: boolean;
    w?: number | 'majority' | TagSet;
    wtimeout?: number;
  }

  interface TagSet {
    [k: string]: string;
  }

  interface ModelProperties {
    /** Base Mongoose instance the model uses. */
    base: typeof mongoose;

    /**
     * If this is a discriminator model, baseModelName is the
     * name of the base model.
     */
    baseModelName: String;

    /** Collection the model uses. */
    collection: Collection;

    /** Connection the model uses. */
    db: Connection;

    /** Registered discriminators for this model. */
    discriminators: any;

    /** The name of the model */
    modelName: string;

    /** Schema the model uses. */
    schema: Schema;
  }

  interface ModelFindByIdAndUpdateOptions {
    /** true to return the modified document rather than the original. defaults to false */
    new?: boolean;
    /** creates the object if it doesn't exist. defaults to false. */
    upsert?: boolean;
    /**
     * if true, runs update validators on this command. Update validators validate the
     * update operation against the model's schema.
     */
    runValidators?: boolean;
    /**
     * if this and upsert are true, mongoose will apply the defaults specified in the model's
     * schema if a new document is created. This option only works on MongoDB >= 2.4 because
     * it relies on MongoDB's $setOnInsert operator.
     */
    setDefaultsOnInsert?: boolean;
    /** if multiple docs are found by the conditions, sets the sort order to choose which doc to update */
    sort?: Object;
    /** sets the document fields to return */
    select?: Object;
    /** if true, passes the raw result from the MongoDB driver as the third callback parameter */
    passRawResult?: boolean;
    /** overwrites the schema's strict mode option for this update */
    strict?: boolean;
    /** 
     * if true, run all setters defined on the associated model's schema for all fields
     * defined in the query and the update.
     */
    runSettersOnQuery?: boolean;
  }

  interface ModelFindOneAndUpdateOptions extends ModelFindByIdAndUpdateOptions {
    /** Field selection. Equivalent to .select(fields).findOneAndUpdate() */
    fields?: Object | string;
    /** puts a time limit on the query - requires mongodb >= 2.6.0 */
    maxTimeMS?: number;
    /** if true, passes the raw result from the MongoDB driver as the third callback parameter */
    passRawResult?: boolean;
  }

  interface ModelPopulateOptions {
    /** space delimited path(s) to populate */
    path: string;
    /** optional fields to select */
    select?: any;
    /** optional query conditions to match */
    match?: Object;
    /** optional name of the model to use for population */
    model?: string;
    /** optional query options like sort, limit, etc */
    options?: Object;
    /** deep populate */
    populate?: ModelPopulateOptions | ModelPopulateOptions[];
  }

  interface ModelUpdateOptions {
    /** safe mode (defaults to value set in schema (true)) */
    safe?: boolean;
    /** whether to create the doc if it doesn't match (false) */
    upsert?: boolean;
    /** whether multiple documents should be updated (false) */
    multi?: boolean;
    /**
     * If true, runs update validators on this command. Update validators validate
     * the update operation against the model's schema.
     */
    runValidators?: boolean;
    /**
     * If this and upsert are true, mongoose will apply the defaults specified in the
     * model's schema if a new document is created. This option only works on MongoDB >= 2.4
     * because it relies on MongoDB's $setOnInsert operator.
     */
    setDefaultsOnInsert?: boolean;
    /** overrides the strict option for this update */
    strict?: boolean;
    /** disables update-only mode, allowing you to overwrite the doc (false) */
    overwrite?: boolean;
    /** other options */
    [other: string]: any;
  }

  interface ModelMapReduceOption<T, Key, Val> {
    map: Function | string;
    reduce: (key: Key, vals: T[]) => Val;
    /** query filter object. */
    query?: Object;
    /** sort input objects using this key */
    sort?: Object;
    /** max number of documents */
    limit?: number;
    /** keep temporary data default: false */
    keeptemp?: boolean;
    /** finalize function */
    finalize?: (key: Key, val: Val) => Val;
    /** scope variables exposed to map/reduce/finalize during execution */
    scope?: Object;
    /** it is possible to make the execution stay in JS. Provided in MongoDB > 2.0.X default: false */
    jsMode?: boolean;
    /** provide statistics on job execution time. default: false */
    verbose?: boolean;
    readPreference?: string;
    /** sets the output target for the map reduce job. default: {inline: 1} */
    out?: {
      /** the results are returned in an array */
      inline?: number;
      /**
       * {replace: 'collectionName'} add the results to collectionName: the
       * results replace the collection
       */
      replace?: string;
      /**
       * {reduce: 'collectionName'} add the results to collectionName: if
       * dups are detected, uses the reducer / finalize functions
       */
      reduce?: string;
      /**
       * {merge: 'collectionName'} add the results to collectionName: if
       * dups exist the new docs overwrite the old
       */
      merge?: string;
    };
  }

  interface MapReduceResult<Key, Val> {
    _id: Key;
    value: Val;
  }

  /*
   * section collection.js
   * http://mongoosejs.com/docs/api.html#collection-js
   */
  interface CollectionBase extends mongodb.Collection {
    /*
      * Abstract methods. Some of these are already defined on the
      * mongodb.Collection interface so they've been commented out.
      */
    ensureIndex(...args: any[]): any;
    //find(...args: any[]): any;
    findAndModify(...args: any[]): any;
    //findOne(...args: any[]): any;
    getIndexes(...args: any[]): any;
    //insert(...args: any[]): any;
    //mapReduce(...args: any[]): any;
    //save(...args: any[]): any;
    //update(...args: any[]): any;

    /** The collection name */
    collectionName: string;
    /** The Connection instance */
    conn: Connection;
    /** The collection name */
    name: string;
  }
}