Add update command to firebase_database (flutter#152)

* update command

* Update command

* Compile error fixed

* dart formatting

* reverting back to master version

* Adding test case for update command

* always specify types

* attempting to fix travis

* Small re-formatting

* Small re-formatting

Author: arashbi

packages/firebase_database/android/src/main/java/io/flutter/plugins/firebase/database/FirebaseDatabasePlugin.java

@@ -260,6 +260,15 @@ public void onMethodCall(MethodCall call, final Result result) {
           break;
         }
 
+      case "DatabaseReference#update":
+        {
+          Map<String, Object> arguments = call.arguments();
+          Map value = (Map) arguments.get("value");
+          DatabaseReference reference = getReference(arguments);
+          reference.updateChildren(value, new DefaultCompletionListener(result));
+          break;
+        }
+
       case "DatabaseReference#setPriority":
         {
           Map<String, Object> arguments = call.arguments();

packages/firebase_database/ios/Classes/FirebaseDatabasePlugin.m

@@ -184,6 +184,9 @@ - (void)handleMethodCall:(FlutterMethodCall *)call result:(FlutterResult)result
     [getReference(call.arguments) setValue:call.arguments[@"value"]
                                andPriority:call.arguments[@"priority"]
                        withCompletionBlock:defaultCompletionBlock];
+  } else if ([@"DatabaseReference#update" isEqualToString:call.method]) {
+    [getReference(call.arguments) updateChildValues:call.arguments[@"value"]
+                                withCompletionBlock:defaultCompletionBlock];
   } else if ([@"DatabaseReference#setPriority" isEqualToString:call.method]) {
     [getReference(call.arguments) setPriority:call.arguments[@"priority"]
                           withCompletionBlock:defaultCompletionBlock];

packages/firebase_database/lib/src/database_reference.dart

@@ -77,6 +77,14 @@ class DatabaseReference extends Query {
     );
   }
 
+  /// Update the node with the `value`
+  Future<Null> update(Map<String, dynamic> value) {
+    return _database._channel.invokeMethod(
+      'DatabaseReference#update',
+      <String, dynamic>{'path': path, 'value': value},
+    );
+  }
+
   /// Sets a priority for the data at this Firebase Database location.
   ///
   /// Priorities can be used to provide a custom ordering for the children at a

packages/firebase_database/test/firebase_database_test.dart

@@ -117,6 +117,19 @@ void main() {
           ]),
         );
       });
+      test('update', () async {
+        final dynamic value = <String, dynamic>{'hello': 'world'};
+        await database.reference().child("foo").update(value);
+        expect(
+          log,
+          equals(<MethodCall>[
+            new MethodCall(
+              'DatabaseReference#update',
+              <String, dynamic>{'path': 'foo', 'value': value},
+            ),
+          ]),
+        );
+      });
 
       test('setPriority', () async {
         final int priority = 42;