[Android][IOS][Firestore] add arrayRemove and arrayUnion to FieldValue (#1624)

### Summary

Add methods arrayRemove and arrayUnion to work with arrays in firestore.

Fixes #1389

### Checklist
* [x]  Supports `Android`
* [x]  Supports `iOS`
* [x]  `e2e` tests added or updated in [/tests/e2e/*](/tests/e2e)
* [x]  Updated the documentation in the [docs repo](https://github.com/invertase/react-native-firebase-docs)

https://github.com/invertase/react-native-firebase-docs/pull/134

* [x]  Flow types updated
* [x]  Typescript types updated

android/src/main/java/io/invertase/firebase/firestore/FirestoreSerialize.java

@@ -68,6 +68,10 @@ class FirestoreSerialize {
   private static final String TYPE_FIELDVALUE = "fieldvalue";
   private static final String TYPE_FIELDVALUE_DELETE = "delete";
   private static final String TYPE_FIELDVALUE_TIMESTAMP = "timestamp";
+  private static final String TYPE_FIELDVALUE_UNION = "union";
+  private static final String TYPE_FIELDVALUE_REMOVE = "remove";
+  private static final String TYPE_FIELDVALUE_TYPE = "type";
+  private static final String TYPE_FIELDVALUE_ELEMENTS = "elements";
 
   // Document Change Types
   private static final String CHANGE_ADDED = "added";
@@ -446,7 +450,9 @@ class FirestoreSerialize {
     }
 
     if (TYPE_FIELDVALUE.equals(type)) {
-      String fieldValueType = typeMap.getString(VALUE);
+      ReadableMap fieldValueMap = typeMap.getMap(VALUE);
+      String fieldValueType = fieldValueMap.getString(TYPE_FIELDVALUE_TYPE);
+
 
       if (TYPE_FIELDVALUE_TIMESTAMP.equals(fieldValueType)) {
         return FieldValue.serverTimestamp();
@@ -456,6 +462,16 @@ class FirestoreSerialize {
         return FieldValue.delete();
       }
 
+      if (TYPE_FIELDVALUE_UNION.equals(fieldValueType)) {
+        ReadableArray elements = fieldValueMap.getArray(TYPE_FIELDVALUE_ELEMENTS);
+        return FieldValue.arrayUnion(elements.toArrayList().toArray());
+      }
+
+      if (TYPE_FIELDVALUE_REMOVE.equals(fieldValueType)) {
+        ReadableArray elements = fieldValueMap.getArray(TYPE_FIELDVALUE_ELEMENTS);
+        return FieldValue.arrayRemove(elements.toArrayList().toArray());
+      }
+
       Log.w(TAG, "Unknown FieldValue type: " + fieldValueType);
       return null;
     }

ios/RNFirebase/firestore/RNFirebaseFirestoreDocumentReference.m

@@ -37,6 +37,10 @@ static NSString *const typeTimestamp = @"timestamp";
 static NSString *const typeReference = @"reference";
 static NSString *const typeDocumentId = @"documentid";
 static NSString *const typeFieldValue = @"fieldvalue";
+static NSString *const typeFieldValueUnion = @"union";
+static NSString *const typeFieldValueRemove = @"remove";
+static NSString *const typeFieldValueType = @"type";
+static NSString *const typeFieldValueElements = @"elements";
 
 - (id)initWithPath:(RCTEventEmitter *)emitter
     appDisplayName:(NSString *)appDisplayName
@@ -408,8 +412,9 @@ static NSString *const typeFieldValue = @"fieldvalue";
   }
 
   if ([type isEqualToString:typeFieldValue]) {
-    NSString *string = (NSString *) value;
-
+    NSDictionary *fieldValueMap = (NSDictionary *) value;
+    NSString *string = (NSString *) fieldValueMap[typeFieldValueType];
+      
     if ([string isEqualToString:typeDelete]) {
       return [FIRFieldValue fieldValueForDelete];
     }
@@ -417,6 +422,16 @@ static NSString *const typeFieldValue = @"fieldvalue";
     if ([string isEqualToString:typeTimestamp]) {
       return [FIRFieldValue fieldValueForServerTimestamp];
     }
+      
+    if ([string isEqualToString:typeFieldValueUnion]) {
+      NSDictionary *elements = (NSDictionary *) value[typeFieldValueElements];
+      return [FIRFieldValue fieldValueForArrayUnion:elements];
+    }
+      
+    if ([string isEqualToString:typeFieldValueRemove]) {
+      NSDictionary *elements = (NSDictionary *) value[typeFieldValueElements];
+      return [FIRFieldValue fieldValueForArrayRemove:elements];
+    }
 
     DLog(@"RNFirebaseFirestore: Unsupported field-value sent to parseJSTypeMap - value is %@",
          NSStringFromClass([value class]));

src/index.d.ts

@@ -2404,10 +2404,16 @@ declare module 'react-native-firebase' {
         constructor(...segments: string[]);
       }
 
+      type AnyJs = null | undefined | boolean | number | string | object;
+
       class FieldValue {
         static delete(): FieldValue;
 
         static serverTimestamp(): FieldValue;
+
+        static arrayUnion(...elements: AnyJs[]): FieldValue;
+
+        static arrayRemove(...elements: AnyJs[]): FieldValue;
       }
 
       class GeoPoint {

src/modules/firestore/FieldValue.js

@@ -2,16 +2,45 @@
  * @flow
  * FieldValue representation wrapper
  */
+import AnyJs from './utils/any';
 
+// TODO: Salakar: Refactor in v6
 export default class FieldValue {
+  _type: string;
+
+  _elements: AnyJs[] | any;
+
+  constructor(type: string, elements?: AnyJs[]) {
+    this._type = type;
+    this._elements = elements;
+  }
+
+  get type(): string {
+    return this._type;
+  }
+
+  get elements(): AnyJs[] {
+    return this._elements;
+  }
+
   static delete(): FieldValue {
-    return DELETE_FIELD_VALUE;
+    return new FieldValue(TypeFieldValueDelete);
   }
 
   static serverTimestamp(): FieldValue {
-    return SERVER_TIMESTAMP_FIELD_VALUE;
+    return new FieldValue(TypeFieldValueTimestamp);
+  }
+
+  static arrayUnion(...elements: AnyJs[]) {
+    return new FieldValue(TypeFieldValueUnion, elements);
+  }
+
+  static arrayRemove(...elements: AnyJs[]) {
+    return new FieldValue(TypeFieldValueRemove, elements);
   }
 }
 
-export const DELETE_FIELD_VALUE = new FieldValue();
-export const SERVER_TIMESTAMP_FIELD_VALUE = new FieldValue();
+export const TypeFieldValueDelete = 'delete';
+export const TypeFieldValueRemove = 'remove';
+export const TypeFieldValueUnion = 'union';
+export const TypeFieldValueTimestamp = 'timestamp';

src/modules/firestore/utils/any.js

@@ -0,0 +1,4 @@
+/**
+ *  @url https://github.com/firebase/firebase-js-sdk/blob/master/packages/firestore/src/util/misc.ts#L26
+ */
+export type AnyJs = null | undefined | boolean | number | string | object;

src/modules/firestore/utils/serialize.js

@@ -5,10 +5,7 @@
 import DocumentReference from '../DocumentReference';
 import Blob from '../Blob';
 import { DOCUMENT_ID } from '../FieldPath';
-import {
-  DELETE_FIELD_VALUE,
-  SERVER_TIMESTAMP_FIELD_VALUE,
-} from '../FieldValue';
+import FieldValue from '../FieldValue';
 import GeoPoint from '../GeoPoint';
 import Path from '../Path';
 import { typeOf } from '../../../utils';
@@ -72,20 +69,6 @@ export const buildTypeMap = (value: any): NativeTypeMap | null => {
     };
   }
 
-  if (value === DELETE_FIELD_VALUE) {
-    return {
-      type: 'fieldvalue',
-      value: 'delete',
-    };
-  }
-
-  if (value === SERVER_TIMESTAMP_FIELD_VALUE) {
-    return {
-      type: 'fieldvalue',
-      value: 'timestamp',
-    };
-  }
-
   if (value === DOCUMENT_ID) {
     return {
       type: 'documentid',
@@ -139,6 +122,17 @@ export const buildTypeMap = (value: any): NativeTypeMap | null => {
       };
     }
 
+    // TODO: Salakar: Refactor in v6 - add internal `type` flag
+    if (value instanceof FieldValue) {
+      return {
+        type: 'fieldvalue',
+        value: {
+          elements: value.elements,
+          type: value.type,
+        },
+      };
+    }
+
     return {
       type: 'object',
       value: buildNativeMap(value),

tests/e2e/firestore/fieldValue.e2e.js

@@ -7,7 +7,7 @@ const {
 
 describe('firestore()', () => {
   describe('FieldValue', () => {
-    before(async () => {
+    beforeEach(async () => {
       await resetTestCollectionDoc(DOC_2_PATH, DOC_2);
     });
 
@@ -46,5 +46,42 @@ describe('firestore()', () => {
         );
       });
     });
+    describe('arrayUnion()', () => {
+      it('should add new values to array field', async () => {
+        const { data } = await testCollectionDoc(DOC_2_PATH).get();
+        should.equal(data().elements, undefined);
+
+        await testCollectionDoc(DOC_2_PATH).update({
+          elements: firebase.firestore.FieldValue.arrayUnion('element 1'),
+          elements2: firebase.firestore.FieldValue.arrayUnion('element 2'),
+        });
+
+        const { data: dataAfterUpdate } = await testCollectionDoc(
+          DOC_2_PATH
+        ).get();
+
+        dataAfterUpdate().elements.should.containDeep(['element 1']);
+        dataAfterUpdate().elements2.should.containDeep(['element 2']);
+      });
+    });
+    describe('arrayRemove()', () => {
+      it('should remove value from array', async () => {
+        await testCollectionDoc(DOC_2_PATH).set({
+          elements: ['element 1', 'element 2'],
+        });
+        const { data } = await testCollectionDoc(DOC_2_PATH).get();
+        data().elements.should.containDeep(['element 1', 'element 2']);
+
+        await testCollectionDoc(DOC_2_PATH).update({
+          elements: firebase.firestore.FieldValue.arrayRemove('element 2'),
+        });
+
+        const { data: dataAfterUpdate } = await testCollectionDoc(
+          DOC_2_PATH
+        ).get();
+
+        dataAfterUpdate().elements.should.not.containDeep(['element 2']);
+      });
+    });
   });
 });