Processing $http response in service

Processing $http response in service

I recently posted a detailed description of the issue I am facing here at SO. As I couldn’t send an actual $http request, I used timeout to simulate asynchronous behavior. Data binding from my model to view is working correct, with the help of @Gloopy
Now, when I use $http instead of $timeout (tested locally), I could see the asynchronous request was successful and data is filled with json response in my service. But, my view is not updating.
updated Plunkr here

Solutions/Answers:

Solution 1:

Here is a Plunk that does what you want: http://plnkr.co/edit/TTlbSv?p=preview

The idea is that you work with promises directly and their “then” functions to manipulate and access the asynchronously returned responses.

app.factory('myService', function($http) {
  var myService = {
    async: function() {
      // $http returns a promise, which has a then function, which also returns a promise
      var promise = $http.get('test.json').then(function (response) {
        // The then function here is an opportunity to modify the response
        console.log(response);
        // The return value gets picked up by the then in the controller.
        return response.data;
      });
      // Return the promise to the controller
      return promise;
    }
  };
  return myService;
});

app.controller('MainCtrl', function( myService,$scope) {
  // Call the async method and then do stuff with what is returned inside our own then function
  myService.async().then(function(d) {
    $scope.data = d;
  });
});

Here is a slightly more complicated version that caches the request so you only make it first time (http://plnkr.co/edit/2yH1F4IMZlMS8QsV9rHv?p=preview):

app.factory('myService', function($http) {
  var promise;
  var myService = {
    async: function() {
      if ( !promise ) {
        // $http returns a promise, which has a then function, which also returns a promise
        promise = $http.get('test.json').then(function (response) {
          // The then function here is an opportunity to modify the response
          console.log(response);
          // The return value gets picked up by the then in the controller.
          return response.data;
        });
      }
      // Return the promise to the controller
      return promise;
    }
  };
  return myService;
});

app.controller('MainCtrl', function( myService,$scope) {
  $scope.clearData = function() {
    $scope.data = {};
  };
  $scope.getData = function() {
    // Call the async method and then do stuff with what is returned inside our own then function
    myService.async().then(function(d) {
      $scope.data = d;
    });
  };
});

Solution 2:

Let it be simple. It’s as simple as

  1. Return promise in your service(no need to use then in service)
  2. Use then in your controller
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Demo. http://plnkr.co/edit/cbdG5p?p=preview

var app = angular.module('plunker', []);

app.factory('myService', function($http) {
  return {
    async: function() {
      return $http.get('test.json');  //1. this returns promise
    }
  };
});

app.controller('MainCtrl', function( myService,$scope) {
  myService.async().then(function(d) { //2. so you can use .then()
    $scope.data = d;
  });
});

Solution 3:

Because it is asynchronous, the $scope is getting the data before the ajax call is complete.

You could use $q in your service to create promise and give it back to
controller, and controller obtain the result within then() call against promise.

In your service,

app.factory('myService', function($http, $q) {
  var deffered = $q.defer();
  var data = [];  
  var myService = {};

  myService.async = function() {
    $http.get('test.json')
    .success(function (d) {
      data = d;
      console.log(d);
      deffered.resolve();
    });
    return deffered.promise;
  };
  myService.data = function() { return data; };

  return myService;
});

Then, in your controller:

app.controller('MainCtrl', function( myService,$scope) {
  myService.async().then(function() {
    $scope.data = myService.data();
  });
});

Solution 4:

tosh shimayama have a solution but you can simplify a lot if you use the fact that $http returns promises and that promises can return a value:

app.factory('myService', function($http, $q) {
  myService.async = function() {
    return $http.get('test.json')
    .then(function (response) {
      var data = reponse.data;
      console.log(data);
      return data;
    });
  };

  return myService;
});

app.controller('MainCtrl', function( myService,$scope) {
  $scope.asyncData = myService.async();
  $scope.$watch('asyncData', function(asyncData) {
    if(angular.isDefined(asyncData)) {
      // Do something with the returned data, angular handle promises fine, you don't have to reassign the value to the scope if you just want to use it with angular directives
    }
  });

});

A little demonstration in coffeescript: http://plunker.no.de/edit/ksnErx?live=preview

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Your plunker updated with my method: http://plnkr.co/edit/mwSZGK?p=preview

Solution 5:

A much better way I think would be something like this:

Service:

app.service('FruitsManager',function($q){

    function getAllFruits(){
        var deferred = $q.defer();

        ...

        // somewhere here use: deferred.resolve(awesomeFruits);

        ...

        return deferred.promise;
    }

    return{
        getAllFruits:getAllFruits
    }

});

And in the controller you can simply use:

$scope.fruits = FruitsManager.getAllFruits();

Angular will automatically put the resolved awesomeFruits into the $scope.fruits.

Solution 6:

I had the same problem, but when I was surfing on the internet I understood that $http return back by default a promise, then I could use it with “then” after return the “data”. look at the code:

 app.service('myService', function($http) {
       this.getData = function(){
         var myResponseData = $http.get('test.json').then(function (response) {
            console.log(response);.
            return response.data;
          });
         return myResponseData;

       }
});    
 app.controller('MainCtrl', function( myService, $scope) {
      // Call the getData and set the response "data" in your scope.  
      myService.getData.then(function(myReponseData) {
        $scope.data = myReponseData;
      });
 });