Is it possible to use AngularJS promises without callbacks?

Question

Is it possible to use AngularJS promises without callbacks?

Typically, when I want to retrieve data asynchronously, I would use the following approach:

var promise = $http.get('/api/v1/movies/avengers');

promise.then(
  function(payload) {
    $scope.movieContent = payload;
  });

This scenario is quite common - sending a request and assigning everything it returns to a variable or property once it's ready. However, it always requires a callback, even if the callback remains the same every time.

Is there a way to achieve something like this instead?

$scope.movieContent = $http.get('/api/v1/movies/avengers'); // updates with real value once request is complete

Or perhaps something similar to:

updateWhenReady($scope.movieContent , '/api/v1/movies/avengers');

It may seem minor, but in my opinion, it can make a difference when used frequently.

javascript ajax angularjs asynchronous angular-promise

Answer 1

Answer №1

Create your service in a way that it initially returns an empty reference and fills up with data once the service call is successful. Utilize angular.copy to keep the reference intact:

Service

app.factory('avengersService', function($http) {
   return  {
      getAvengers: function() {
         var avengers = [];
         avengers.$promise = $http.get('/api/v1/movies/avengers').then(function(result) {
             angular.copy(result.data, avengers);
             return result;
         });
         return avengers;
      }
   }
});

Controller

app.controller('ctrl', function($scope, avengersService) {
    $scope.movieContent = avengersService.getAvengers();

    // or call the promise version
    avengersService.getAvengers().$promise.then(function(result) {
         $scope.movieContent = result.data;
    });

});

Answer 2

Create your service in a way that it initially returns an empty reference and fills up with data once the service call is successful. Utilize angular.copy to keep the reference intact:

Service

app.factory('avengersService', function($http) {
   return  {
      getAvengers: function() {
         var avengers = [];
         avengers.$promise = $http.get('/api/v1/movies/avengers').then(function(result) {
             angular.copy(result.data, avengers);
             return result;
         });
         return avengers;
      }
   }
});

Controller

app.controller('ctrl', function($scope, avengersService) {
    $scope.movieContent = avengersService.getAvengers();

    // or call the promise version
    avengersService.getAvengers().$promise.then(function(result) {
         $scope.movieContent = result.data;
    });

});

Answer 3

Answer №2

An alternative approach is to encapsulate the asynchronous call within a custom function:

function fetchData(callback, dataModel){
        callback.then(function(response){
            dataModel = response;
        });
    }

*However, it is advisable to avoid this method. It is more beneficial to utilize the callback function for executing specific operations (such as displaying loading indicators, etc).

Answer 4

An alternative approach is to encapsulate the asynchronous call within a custom function:

function fetchData(callback, dataModel){
        callback.then(function(response){
            dataModel = response;
        });
    }

*However, it is advisable to avoid this method. It is more beneficial to utilize the callback function for executing specific operations (such as displaying loading indicators, etc).

Answer 5

Answer №3

While it may not be exactly what you were looking for, there is a way to create these callbacks dynamically:

function addToScope(property) {
    return function (data) { $scope[property] = data; };
}

$http.get('/api/v1/movies/avengers').then(addToScope('movieContent'));

Alternatively, you can use this syntax:

function addToScope(property, promise) {
    promise.then(function (data) { $scope[property] = data; });
}

addToScope('movieContent', $http.get('/api/v1/movies/avengers'));

Remember to handle errors properly. If the promise fails, it's important to inform the user.

Answer 6

While it may not be exactly what you were looking for, there is a way to create these callbacks dynamically:

function addToScope(property) {
    return function (data) { $scope[property] = data; };
}

$http.get('/api/v1/movies/avengers').then(addToScope('movieContent'));

Alternatively, you can use this syntax:

function addToScope(property, promise) {
    promise.then(function (data) { $scope[property] = data; });
}

addToScope('movieContent', $http.get('/api/v1/movies/avengers'));

Remember to handle errors properly. If the promise fails, it's important to inform the user.

Is it possible to use AngularJS promises without callbacks?

Answer №1

Answer №2

Answer №3

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