通过承诺返回错误

Question

I am pretty new to AngularJS and Javascript. I am creating a app in which I am planning to use one function to do all ajax related operation(factory in angularjs). This function will be only one gateway for all ajax operations. When I return promise as a success it works properly. but returning error promise do not work.

Here is a sample code. I am expecting return of promise in error function if promise fails but it goes to success

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

myApp.controller('FirstController, function($scope, util){
        util.doAjax().then(function(response){
                // This function is called in both success and error
            }, function(err){
                // This is never called why ?                
            });
});

myApp.factory('util, function($http){
    return $http({
       method: 'GET',
       url: 'http://www.example.com'
    }).then(function(response){
        // This will return success promise
        return response;
    }, function(err){
        // This should return error promise
        return err;
    });
});

Answer 1

Currently you are directly returning a data from error function, which is chaining the promise and calling it underlying .then method.

While returning an error you have to reject a promise by creating a new custom promise using $q

return $q.reject(err)

Other important thing is, you should create method in a service with name

myApp.factory('util', function($http, $q){
 //Exposed method
 return {
   doAjax : function() {
       return $http({
          method: 'GET',
          url: 'http://www.example.com'
       }).then(function(response){
           // This will return success promise
           return response.data; // returned data
       }, function(err){
           // return error promise with err object
           return $q.reject(err);
       });
     }
  }
});