javascript - MorrisJS error: Cannot read property 'label' of undefined -

im using anuglarjs , morris create graph.

i have directive as:

    app.directive('barchart', function() {      return {          // required make work element         restrict: 'e',         template: '<div></div>',         replace: true,         // observe , manipulate dom         link: function($scope, element, attrs) {              var data = $scope[attrs.data],                 xkey = $scope[attrs.xkey],                 ykeys= $scope[attrs.ykeys],                 labels= $scope[attrs.labels];              morris.bar({                 element: element,                 data: data,                 xkey: xkey,                 ykeys: ykeys,                 labels: labels             });          }      }; }); 

my service data api:

services.factory('temp', function ($resource) {     return $resource('http://localhost/api/temp', {}, {         query: { method: 'get',  isarray: true}      }) }); 

and controller:

app.controller('samplecontroller', ['$scope', 'temp',     function($scope, temp){      $scope.xkey = 'date';      $scope.ykeys = ['temp', 'humidity'];      $scope.labels = ['temperature', 'humidity'];      $scope.mymodel = temp.query();         console.log($scope.mymodel);  }]); 

the problem error: cannot read property 'label' of undefined. api returns json array looks this:

[{"date":"20150717105501","temp":"26","humidity":"38"}, {"date":"20150717105401","temp":"26","humidity":"38"}, {"date":"20150717105301","temp":"26","humidity":"37"}, {"date":"20150717105101","temp":"36","humidity":"0"}] 

i dont see problem, im new angular. thank you!