Injecting services into AngularJS controllers helps to provide the necessary dependencies

Greetings! Here is the code snippet for my service:

angular.module('lucho1App').factory('ApiExample', ['$http', '$q', function($http, $q) {
    return {
        promiseToHaveData: function() {
            return $http.get('http://data.colorado.gov/resource/4ykn-tg5h.json').then(function(response) {
                var result = response.data;
                console.log(result);
                return result;
            }, function(response) {
                console.log('An error has occurred');
            });
        }
    };
}]);

Additionally, here is the controller associated with the service:

angular.module('lucho1App')
  .controller('MainCtrl',['$scope', 'ApiExample',function MainCtrl($scope,ApiExample) {

    $scope.apiExampl=ApiExample.promiseToHaveData();
    console.log($scope.apiExampl);
}]);

In the above setup, the console.log in the service displays output indicating a successful request. However, in the controller, $scope.apiExampl returns as undefined. What could be causing this discrepancy?

Answer №1

When working with promises, it's important to remember that they are asynchronous. This means that the resolution of the promise will happen at a later time, triggering the function in the 'then' method. By using the return statement within the callback function, you can modify the object that is passed to the next 'then' call, as promises allow for chaining.

To start off, make sure to return the promise object in your service:

return $http.get(...);

Next, update your controller code like so:

ApiExample.promiseToHaveData().then(function(data){
    $scope.apiExampl=data;
});

It's worth noting that in this instance, we use =data because the data has already been extracted from the response within the service.

Answer №2

To retrieve the data, you must use a promise

retrieveDataPromise: function() {
    return $http.get('http://data.colorado.gov/resource/4ykn-tg5h.json');
}

Then, ensure to handle the success callback in your controller

ApiExample.retrieveDataPromise().success (function(response) {
    $scope.apiExample = response.data;
    console.log($scope.apiExample);
});

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