Meanjs built in app, how to update USER array from articles module - node.js

Question

I'm using the Articles and Users implementation into Meanjs built-in app.
List of articles (View) with the button for every item:
<a data-ng-controller="MyArticlesController" data-ng-repeat="article in articles" class="list-group-item">
<button data-ng-click="addArt2me()" class="glyphicon glyphicon-plus addArt2me" ></button>
<h4 class="list-group-item-heading" data-ng-bind="article.title"></h4>
<p> {{article.content | limitTo:140}} </p>
</a>
And here the controller with the trigger function $scope.addArt2me():
'use strict';
angular.module('users').controller('MyArticlesController', ['$scope', 'Articles', 'Users', '$location',
function($scope, Articles, Users, $location) {
var myUser = new Users($scope.user);
$scope.addArt2me = function() {
var myArticle = new Articles($scope.article);
myUser.userArticles.push(myArticle._id);
myUser.$update(function(response) {
console.log("Actualize!! con : " + user.userArticles.length + "__" + response);
}, function(errorResponse) {
console.log("updatError: " + errorResponse);
$scope.error = errorResponse;
});
}
}
]);
In the user's model I've an array of articles._id userArticles.
The View renders a list of articles with a button that triggers the function addArt2me() in the controller, which pushes and updates the myArticle._id inside ´userArticles´.
It works successfully and saves the element into DB :)
console: Actualize!! con : 60__[object Object]
...but only the first time, the next time it triggers an error :(
PUT http://localhost:3000/users 400 (Bad Request)
updatError: [object Object]´
Do I need to deal with some kind of service to update the USERS module being in ARTICLES module?
Can't I just update the model of the user with Mongoose?
Why does it works well for the first saved article ?
Any guide is very appreciated. Thanks!

Answer 1

I just founded, after 2 day of looking for it.
Needed to declare the User Model, outside the subcontroller because it iterates for every article.
so move ´$scope.myUser = new Users($scope.user);´ into ´ArticlesController´ Did the job!
Thanks for your time!