Unraveling JSON data within an AngularJS controller

I'm facing an issue with exposing a field in my AngularJS controller. The problem arises when a JSON 'owner' object is returned by a webservice, containing a field named 'Cave'. If this 'Cave' field has a null, empty, or whitespace value, I want to hide an element in the view using ng-hide. My goal is to expose the 'hideCave' field from the controller as shown below:

function OwnerController($scope, OwnerFactory, $routeParams) {
    if ($scope.owner == null) {
        $scope.owner = OwnerFactory.getOwner($routeParams.id);
        //$scope.hideCaveat = $scope.owner.Cave == undefined;

        //Alerts 'Hide: {}?undefined'
        alert('Hide: ' + JSON.stringify($scope.owner) + '?' + $scope.hideCaveat); 
    }

    $scope.someButton = function () {
        //Alerts full JSON string when clicked
        alert('Hide: ' + JSON.stringify($scope.owner) + '?' + $scope.hideCaveat); 
    }
}

myApp.factory('OwnerFactory', function ($http) {
    return {
        getOwner: function (id) {
            var url = 'api/Owner/' + id;
            return $http.get(url)
            .then(function (response) {
                return response.data;
            });
        }
    }
});

The data loads correctly, but I cannot retrieve a value from $scope.owner.Cave unless I add an ng-click event to trigger it.

Example of JSON returned from web service:

{"FirstName":"David","LastName":"Lynch","Street":"Oak Dr. 7","ZipCode":"90210","Town":"Beverly Hills","Email":"","Cave":"Do not sell this man any more drugs"}

What am I missing that's causing me not to receive the value?

Could my problem be related to creating a global function for my controller? Should I use myApp.controller instead?

Answer №1

Accessing it should be as simple as interacting with any other object.

<div class="alert" ng-show="owner.Cave">{{owner.Cave}}</div>

Check out the Plunker demo for reference. I have manually inputted the data in the Plunker example.

Answer №2

Have you attempted implementing ng-show="owner.Cave" in your template? It ought to function correctly.

The explanation for receiving an empty object in the alert is due to the fact that $http.get is not a synchronous operation. It provides a promise - so when you reach the alert, you are still dealing with the promise. Only after it has been resolved - like before clicking the button - will you be able to see the real data.

Answer №3

myApp.factory('OwnerFactory', function ($http) {
    return {
        fetchOwnerDetails: function (id) {
            var endpoint = 'api/Owner/' + id;
            return $http.get(endpoint);
        }
    }
});

and

$scope.ownerInfo = OwnerFactory.fetchOwnerDetails($routeParams.id).then(function(data){
     $scope.hideCaveat = data.owner.Cave === undefined;
});

due to the fact that fetchOwnerDetails returns a promise.

update

it is advisable to use ng-hide or ng-show directives based on the data attributes you wish to display or conceal

<div ng-show="ownerInfo.Cave">cave details</div>

Answer №4

Make sure to include a watch function at the beginning of your controller to ensure "hideCaveat" is always present.

function OwnerController($scope, OwnerFactory, $routeParams) {
  $scope.$watch( 'owner.Cave', function(cave) {
    if (cave && cave.length > 0) {
      $scope.hideCaveat = false;
    } else {
      $scope.hideCaveat = true;
    }
  });
  ...

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