angular controller not being able to receive data from service

Question

angular controller not being able to receive data from service

Presenting my innovative service:

app.service('trackService', ['$http', function($http) {
    var information;
    this.fetchData = function(limit) {
        $http({
            method: 'GET',
            url: 'http://ws.audioscrobbler.com/2.0/?method=chart.gettoptracks',
            params: {api_key: 'e8452c5962aafbb3e87c66e4aaaf5cbf', format: 'json', limit: limit}
        }).success(function(result) {
            this.information = result.tracks; console.log(this.information); return this.information;
        }); 
    }
}]);

and accompanying controller -

app.controller('artistSongsCtrl', ['$scope', 'trackService', function($scope, trackService) {
    $scope.data = trackService.fetchData(10);
    //console.log($scope.data);
}]);

What is the best approach to transfer data to the controller using a $http service within a custom service?

javascript angularjs json angular-services

Answer 1

Answer №1

There are a few issues with your code. Firstly, the $http function is asynchronous and your service method topTracks() does not return anything. Additionally, you cannot use return inside the success function, as there is no way to return from it - you should use then() instead.

In order to resolve these problems, you need to return the promise from the service and set the scope in a promise callback within the controller.

app.service('trackService', ['$http',
  function($http) {
    var data;
    var self = this;
    this.topTracks = function(limit) {
      return $http({
        method: 'GET',
        url: 'http://ws.audioscrobbler.com/2.0/?method=chart.gettoptracks',
        params: {
          api_key: 'e8452c5962aafbb3e87c66e4aaaf5cbf',
          format: 'json',
          limit: limit
        }
      }).then(function(result) {
        self.data = result.data.tracks;
        console.log(self.data);
        return self.data;
      });
    }
  }
]);

app.controller('artistSongsCtrl', ['$scope', 'trackService',
  function($scope, trackService) {
    trackService.topTracks(10).then(function(data) {
      $scope.data = data;
      //console.log($scope.data);
    });

  }
]);

Answer 2

There are a few issues with your code. Firstly, the $http function is asynchronous and your service method topTracks() does not return anything. Additionally, you cannot use return inside the success function, as there is no way to return from it - you should use then() instead.

In order to resolve these problems, you need to return the promise from the service and set the scope in a promise callback within the controller.

app.service('trackService', ['$http',
  function($http) {
    var data;
    var self = this;
    this.topTracks = function(limit) {
      return $http({
        method: 'GET',
        url: 'http://ws.audioscrobbler.com/2.0/?method=chart.gettoptracks',
        params: {
          api_key: 'e8452c5962aafbb3e87c66e4aaaf5cbf',
          format: 'json',
          limit: limit
        }
      }).then(function(result) {
        self.data = result.data.tracks;
        console.log(self.data);
        return self.data;
      });
    }
  }
]);

app.controller('artistSongsCtrl', ['$scope', 'trackService',
  function($scope, trackService) {
    trackService.topTracks(10).then(function(data) {
      $scope.data = data;
      //console.log($scope.data);
    });

  }
]);

Answer 3

Answer №2

Within your service, an asynchronous GET request is being made. To ensure the controller can capture and handle this response, it's necessary to return a promise. Below is an example that utilizes $q:

app.service('trackService', ['$http', '$q', function($http, $q) {
    var data;
    this.topTracks = function(limit) {
        var deferred = $q.defer();
        $http({
            method: 'GET',
            url: 'http://ws.audioscrobbler.com/2.0/?method=chart.gettoptracks',
            params: {api_key: 'e8452c5962aafbb3e87c66e4aaaf5cbf', format: 'json', limit: limit}
        }).success(function(result) {
            this.data = result.tracks; 
            console.log(this.data); 
            deferred.resolve(this.data);
        }); 
     return deferred.promise;
    }
}]);

Answer 4

Within your service, an asynchronous GET request is being made. To ensure the controller can capture and handle this response, it's necessary to return a promise. Below is an example that utilizes $q:

app.service('trackService', ['$http', '$q', function($http, $q) {
    var data;
    this.topTracks = function(limit) {
        var deferred = $q.defer();
        $http({
            method: 'GET',
            url: 'http://ws.audioscrobbler.com/2.0/?method=chart.gettoptracks',
            params: {api_key: 'e8452c5962aafbb3e87c66e4aaaf5cbf', format: 'json', limit: limit}
        }).success(function(result) {
            this.data = result.tracks; 
            console.log(this.data); 
            deferred.resolve(this.data);
        }); 
     return deferred.promise;
    }
}]);

angular controller not being able to receive data from service

Answer №1

Answer №2

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