Merge pull request #215 from mikepugh/master

Add support for transaction method via $transaction

Author: anantn

.gitignore

@@ -2,3 +2,4 @@ bower_components/
 node_modules/
 bower_components/
 selenium/
+.idea

angularfire.js

@@ -240,6 +240,36 @@
         return deferred.promise;
       };
 
+      // Update a value within a transaction. Calling this is the
+      // equivalent of calling `transaction()` on a Firebase reference.
+      //
+      //  * `updateFn`:     A developer-supplied function which will be passed the current data
+      //                    stored at this location (as a Javascript object). The function should
+      //                    return the new value it would like written (as a Javascript object).
+      //                    If "undefined" is returned (i.e. you "return;" with no arguments) the
+      //                    transaction will be aborted and the data at this location will not be modified.
+      //  * `applyLocally`: By default, events are raised each time the transaction update function runs. So
+      //                    if it is run multiple times, you may see intermediate states. You can set this
+      //                    to false to suppress these intermediate states and instead wait until the
+      //                    transaction has completed before events are raised.
+      //
+      //  This function returns a promise that will be resolved when the transaction function has completed.
+      //  A successful transaction is resolved with the snapshot. If the transaction is aborted,
+      //  the promise will be resolved with null.
+      object.$transaction = function(updateFn, applyLocally) {
+        var deferred = self._q.defer();
+        self._fRef.ref().transaction(updateFn, function(err, committed, snapshot) {
+          if(err) {
+            deferred.reject(err);
+          } else if(!committed) {
+            deferred.resolve(null);
+          } else {
+            deferred.resolve(snapshot);
+          }
+        }, applyLocally);
+      };
+
+
       // Remove this object from the remote data. Calling this is the
       // equivalent of calling `remove()` on a Firebase reference. This
       // function takes a single optional argument:

angularfire.min.js

@@ -19,6 +19,7 @@
         <span class="content">{{message.content}}</span>
       </span>
     </div>
+    <em ng-cloak ng-if="messages" class="messageCountBlock"># Messages: {{messageCount.$value}}</em>
   </div>
   <form ng-submit="addMessage()">
     <input id="message" type="text" ng-model="message" placeholder="Message...">
@@ -27,19 +28,36 @@
   <script type="text/javascript">
     var _scope;
     var _url = 'https://angularfiretests.firebaseio.com/chat';
+    var _tnUrl = 'https://angularfiretests.firebaseio.com/chatMsgs';
     angular.module("chat", ["firebase"]);
     function Chat($scope, $firebase) {
       $scope.messages = $firebase(new Firebase(_url).limit(2));
+      $scope.messageCount = $firebase(new Firebase(_tnUrl));
       $scope.username = 'Guest' + Math.floor(Math.random()*101);
       $scope.addMessage = function() {
         var promise = $scope.messages.$add({
           from: $scope.username, content: $scope.message
         });
+
+        // Transaction testing
+        $scope.messageCount.$transaction(function(currentCount) {
+          if(!currentCount) {
+            return 1;
+          } else {
+            return currentCount+1;
+          }
+        });
+
         $scope.message = "";
         return promise;
       }
       _scope = $scope;
     }
+
+    function testMessageCount(expectedCount, node) {
+        return node.innerHTML != '# Messages: ' + expectedCount;
+    }
+
     function testIfInDOM(from, content, node) {
       if (node.childNodes.length != 5) return false;
       if (node.childNodes[1].innerHTML != from + ": ") return false;