The Ionic AngularJS http service is failing to update the controller

Question

The Ionic AngularJS http service is failing to update the controller

I'm struggling to understand why my controller is receiving an empty array after calling the service, which triggers an http call. Here's how I have set up my app:

Here is my app.js file:

//App.js
  .state('myApp.sermonlists', {
    url: "/sermonlists",
    views: {
      'menuContent': {
        templateUrl: "templates/sermonlists.html",
        controller: 'SermonListsCtrl'
      }
    }
  })

This is controller.js:

//controller.js
angular.module('myApp.controllers', [])
.controller('SermonListsCtrl', function($scope, sermonListsService) {
  // call sermon api
  sermonListsService.getSermonLists(); // this returns an empty array()
})

This is services.js:

//services.js
angular.module('myApp.services', [])

.factory('sermonListsService', function($http) {
    var sermon = [];

    function sermonJson() {
        $http.get('http://myapicall.com').then(function(resp) {
          // For JSON responses, resp.data contains the result
          sermon = resp.data;
         }, function(err) {
          console.error('ERR', err);
          // err.status will contain the status code
        })          
    }

    // initializing sermonJson call
    function init() {
        sermonJson();
    }

    // run init()
    init();

    return {
        getSermonLists: function(){

            return sermon;
        },
        getUser: function(index){
            return "";
        }
    }
})

I would appreciate any guidance on best practices and examples to help me resolve this issue.

javascript angularjs ionic-framework promise

Answer 1

Answer №1

In order to resolve the issue of modules not getting injected, it is recommended to either manage their dependencies or ensure that the modules are the same.

Below is a suggested solution:

//controller.js
angular.module('myApp', [])
     .controller('SermonListsCtrl', function($scope, sermonListsService) {
     // call sermon api
      sermonListsService.getSermonLists(); // this returns an empty array()
});


//services.js
 angular.module('myApp', [])

 .factory('sermonListsService', function($http) {
   var sermon = [];

    function getSermons() {
    $http.get('http://myapicall.com').then(function(resp) {
      // For JSON responses, resp.data contains the result
      sermon = resp.data;
     }, function(err) {
      console.error('ERR', err);
      // err.status will contain the status code
    })          
}

// initialize the getSermons function
function init() {
    getSermons();
}

// run init()
init();

return {
    getSermonLists: function(){

        return sermon;
    },
     getUser: function(index){
        return "";
     }
   }
 })

Answer 2

In order to resolve the issue of modules not getting injected, it is recommended to either manage their dependencies or ensure that the modules are the same.

Below is a suggested solution:

//controller.js
angular.module('myApp', [])
     .controller('SermonListsCtrl', function($scope, sermonListsService) {
     // call sermon api
      sermonListsService.getSermonLists(); // this returns an empty array()
});


//services.js
 angular.module('myApp', [])

 .factory('sermonListsService', function($http) {
   var sermon = [];

    function getSermons() {
    $http.get('http://myapicall.com').then(function(resp) {
      // For JSON responses, resp.data contains the result
      sermon = resp.data;
     }, function(err) {
      console.error('ERR', err);
      // err.status will contain the status code
    })          
}

// initialize the getSermons function
function init() {
    getSermons();
}

// run init()
init();

return {
    getSermonLists: function(){

        return sermon;
    },
     getUser: function(index){
        return "";
     }
   }
 })

Answer 3

Answer №2

One issue arises when getSermonLists() returns a reference to an empty array, but the $http callback only replaces the internal list instead of filling it. As a result, the return value of getSermonLists() still points to the empty array, even though "var sermon" in the service now references the filled array.

Maintain Same Array Instance

To address this, you can modify the $http callback to add all elements of the response to the array instead of just changing the reference:

$http.get(...).then(function(response) {
    // Add all elements of response.data to sermon
    sermon.push.apply(sermon, response.data);
});

This approach ensures that the controllers also reflect the changes since they share the same array instance.

Utilizing Promises

Another solution is to utilize promises, as suggested earlier. In this scenario, getSermonLists should not return an array but a promise that remains unresolved until the AJAX call is completed. Angular's $q service can be used to create promises:

var sermon = $q.defer();
function getSermonJson() {
    sermon = $http.get(....).then(function(response) {
        sermon.resolve(response.data);
    });
}

getSermonList: function() {
    return sermon;
}

Subsequently, update your controller to handle the promise:

sermonListsService.getSermonLists().then(function(sermonList) {
    // Perform actions with the loaded sermonList, e.g., $scope.sermons = sermonList;
});

By utilizing promises, the controller can wait for the sermons to load and respond accordingly, including handling failed requests.

Answer 4

One issue arises when getSermonLists() returns a reference to an empty array, but the $http callback only replaces the internal list instead of filling it. As a result, the return value of getSermonLists() still points to the empty array, even though "var sermon" in the service now references the filled array.

Maintain Same Array Instance

To address this, you can modify the $http callback to add all elements of the response to the array instead of just changing the reference:

$http.get(...).then(function(response) {
    // Add all elements of response.data to sermon
    sermon.push.apply(sermon, response.data);
});

This approach ensures that the controllers also reflect the changes since they share the same array instance.

Utilizing Promises

Another solution is to utilize promises, as suggested earlier. In this scenario, getSermonLists should not return an array but a promise that remains unresolved until the AJAX call is completed. Angular's $q service can be used to create promises:

var sermon = $q.defer();
function getSermonJson() {
    sermon = $http.get(....).then(function(response) {
        sermon.resolve(response.data);
    });
}

getSermonList: function() {
    return sermon;
}

Subsequently, update your controller to handle the promise:

sermonListsService.getSermonLists().then(function(sermonList) {
    // Perform actions with the loaded sermonList, e.g., $scope.sermons = sermonList;
});

By utilizing promises, the controller can wait for the sermons to load and respond accordingly, including handling failed requests.

The Ionic AngularJS http service is failing to update the controller

Answer №1

Answer №2

Maintain Same Array Instance

Utilizing Promises

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