javascript - Return value from firebase in ng-repeat -

i use angularjs front-end , firebase database.

i have ng-repeat displays firebasearray of stories. each of these stories connected number of collections can part of. collections , stories stored in 2 different locations on firebase server , use keys tie these together.

my model story object in database looks this:

storyid: {     title: 'title',     in_collections: {       0: collectionid //collection id refers specific collection in database       1: collectionid     } } 

so whenever display story object don't have access title, id. in order title need call server name. have this:

template:

<div>   {{story.title}}   in collections:    <span ng-repeat="(key, collection) in story.in_collections">     {{getcollectiontitle(key)}}   <span> </div> 

controller:

app.controller("explorectrl", function($scope, stories, collections){    $scope.story = stories.getstory(storyid); //comes firebase array    $scope.getcollectiontitle = function(collectionid){     collections.getcollectiontitle(collectionid).then(function(title){         console.log(title.val());         return title.val();     });   } }); 

services:

app.factory('collections', function(){   var ref = firebase.database().ref('collections');   return {     getcollectiontitle: function(collectionid){       return ref.child(collectionid).child('title').once('value');     }   } })  .factory('stories', function($firebaseobject){   var ref = firebase.database().ref('stories');   return{     getstory: function(id){       return $firebaseobject(ref.child(id));     }   } }) 

i can see fetches correct collection title in console.log(title.val()) can't find way apply view. empty , keeps being way.

any appreciated. thank much!