AngularJS ng-options无法显示

I have my back-end setup like this.

  public function index()
    {
        $doc = Document::all();
        return response()->json([
            'Success' => [
                'documents' => $doc->toArray()
            ],
        ], 200);
      //  return $doc;
    }

In the front-end I have my factory class like this

  query:
        {
            method:'GET',
            isArray:false
        },

and controller like this.

DocumentsFactory.query(function(documents) {
  $scope.documents = documents;

});

Now this setup runs just fine. Here is my console.log

When I try the following in my html.

<div class="col-sm-5">
            <select class="form-control m-b-sm" id="procedureId" ng-change="getSelectedProcedure(selectedProcedure.item)" ng-model="selectedProcedure.item" ng-options="document as (document.id + '-' + document.name) for document in documents" required="true"/>
            <option value=" ">----------</option>
          </select>
        </div>

It does not work. Simply shows nothing in selection. Am I doing things the wrong way? What is the best practice for this kind of thing?