Insert value into db.json with help of angular-resource

I have a json file named db.json which is like

{
"menu":[
 {
   "id":0,
   "item":"item1"
},{
   "id":1,
   "item":"item2"
},{
   "id":2,
   "item":"item3"
}
],
"feedback":[]
}

I am using angular $resource to PUT an Javascirpt object into the feedback array.

Here is my service code-

this.getFeedbacks = function(){
            return $resource(baseURL + "feedback/:id", null, {
                'update': {
                    method: 'PUT'
                }
            });
        };

And here is the controller code-

$scope.fb.push($scope.myFeedback);
 menuFactory.getFeedbacks().update({
            id: $scope.fb.id
        }, $scope.fb);

Notice that the feedback array in the json is empty and the $scope.myFeedback is found from a ng-controller's ng-model and this ng-controller has a submit button when I click on the submit button then the values of the inputs are stored into the json file.
The HTML code is-

<form name="feedbackForm" ng-submit="setFeedback()">
   <input type="text" name="name" ng-model="myFeedback.name">
   <input type="submit" name="submit" value="feedback">
</form>

My update function is not working why please someone explain it. Note that I am very beginner at angularJS platform and REST client-server networking.