Add new collation methods for mongoose (#16897)

* Add collation methods for query and aggregation

* Add tests for collation

types/mongoose/index.d.ts

@@ -1417,6 +1417,9 @@ declare module "mongoose" {
     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;
 
@@ -1817,6 +1820,17 @@ declare module "mongoose" {
     context?: string;
   }
 
+  interface CollationOptions {
+    locale?: string;
+    caseLevel?: boolean;
+    caseFirst?: string;
+    strength?: number;
+    numericOrdering?: boolean;
+    alternate?: string;
+    maxVariable?: string;
+    backwards?: boolean;
+  }
+
   namespace Schema {
     namespace Types {
       /*
@@ -2089,6 +2103,9 @@ declare module "mongoose" {
      */
     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

types/mongoose/mongoose-tests.ts

@@ -660,6 +660,7 @@ query.catch(cb).catch(cb);
 query.center({}).center({});
 query.centerSphere({ center: [50, 50], radius: 10 }).centerSphere('path', {});
 query.circle({ center: [50, 50], radius: 10 }).circle('path');
+query.collation({ locale: 'en_US', strength: 1 });
 query.comment('comment').comment('comment');
 query.where({color: 'black'}).count(function (err, count) {
   count.toFixed();
@@ -995,6 +996,7 @@ aggregate.addCursorFlag('flag', true).addCursorFlag('', false);
 aggregate.allowDiskUse(true).allowDiskUse(false, []);
 aggregate.append({ $project: { field: 1 }}, { $limit: 2 });
 aggregate.append([{ $match: { daw: 'Logic Audio X' }} ]);
+aggregate.collation({ locale: 'en_US', strength: 1 });
 aggregate.cursor({ batchSize: 1000 }).exec().each(cb);
 aggregate.exec().then(cb).catch(cb);
 aggregate.explain(cb).then(cb).catch(cb);