Angularjs and Typescript - Call a factory

Question

I am using Angularjs and typescript to outsource some REST-Methods to a factory. This factory should be used by different controllers. So I have a simple webpage, a controller and a factory I would like to use:

Here is the code for the controller:

/// <reference path="../scripts/typescript/angular.d.ts" />
/// <reference path="../scripts/app.ts" />
/// <reference path="ServiceHttp.ts" />
module nawApp {
   export interface IStundentScope extends ng.IScope {
      fullname: string;
   }
   export class StudentUse {
      private ServiceHttp: any;
      constructor($scope: IStundentScope, ServiceHttp: nawApp.ServiceHttp, $http: ng.IHttpService) {
         this.ServiceHttp = ServiceHttp;
         $scope.fullname = ServiceHttp.exampleFunction();
      }

   }
   StudentUse.$inject = ['$scope', 'ServiceHttp', '$http'];
   nawApp.app.controller('StudentUse', StudentUse);
}

And here is my factory:

/// <reference path="../scripts/typescript/angular.d.ts" />
/// <reference path="../scripts/app.ts" />
module nawApp {
   export class ServiceHttp {
      private http: any;
      constructor(public  $http: any) {
         this.http = $http;
     }
      public exampleFunction():string {
         this.http.get(mainUrl.toString() + 'EventLog').success(function (data, status, headers, config) {
            try {
               return data;
            }
            catch (err) {
               return "Hello Error";
            }
         }).error(function (data, status, headers, config) {
               return "Hello Error 2";
            });
         return "Hello Error 3";
      }
      static Factory($http: ng.IHttpService) {
         return new ServiceHttp($http);
      }
   }
   ServiceHttp.$inject = ['$http'];
   nawApp.app.factory('ServiceHttp', nawApp.ServiceHttp.Factory);
}

I debugged the code and the Factory($http: ng.IHttpService)... part is executed by using ServiceHttp.exampleFunction(), but the string Hello Error 3 is returned and not the return data; part. If I just copy the HTTP.Get stuff to my controller, everything is fine. I think there is a problem with the way I call the factory.

Can You help me? Thanks!!!

with $http you don't need a deferred

basarat
– basarat

2014-08-18 13:06:42 +00:00
Commented Aug 18, 2014 at 13:06 — basarat
– basarat, Commented Aug 18, 2014 at 13:06

basarat · Accepted Answer · 2014-08-18 13:06:22Z

You could actually just return the chained response from $http:

module nawApp
{
    export class ServiceHttp
    {
        private http: any;
        constructor(public $http: ng.IHttpService, public $q: ng.IQService){
            this.http = $http;
        }
        public exampleFunction(): ng.IPromise<string>{

            return this.http.get(mainUrl.toString() + 'EventLog').success(function (data, status, headers, config){
                return data.SomeStringProperty;
            }).error(function (data, status, headers, config){
                throw new Error('Custom error message');
            });
        }

        static Factory($http: ng.IHttpService){
            return new ServiceHttp($http);
        }
    }
    ServiceHttp.$inject = ['$http', '$q'];
    nawApp.app.factory('ServiceHttp', nawApp.ServiceHttp.Factory);
}

Note that use deferred needlessly is a bad pattern : https://github.com/petkaantonov/bluebird/wiki/Promise-anti-patterns#the-deferred-anti-pattern

Really interesting link! And a + for your, because that is really surprising anti pattern, really interesting...
You can also replace ServiceHttp.$inject with static $inject property inside the class and replace function (data, status, headers, config) with arrow functions (better, typed arrow functions)

David Bohunek · Accepted Answer · 2014-08-18 13:22:12Z

You must return a promise from your exampleFunction function instead of a string. Then depending on result of the HTTP call, you either resolve or reject the promise. Key is the return value of your function which should be ng.IPromise<string>. Also note that you can used type ng.IHttpService for the $http service instead of just any.

The service could look like then:

module nawApp
{
    export class ServiceHttp
    {
        private http: any;
        constructor(public $http: ng.IHttpService){
            this.http = $http;
        }
        public exampleFunction(): ng.IPromise<string>{

            return this.http.get(mainUrl.toString() + 'EventLog').success(function (data, status, headers, config){
               return data;
            }).error(function (data, status, headers, config){
               throw new Error("Error");
            });
        }

        static Factory($http: ng.IHttpService){
            return new ServiceHttp($http);
        }
    }
    ServiceHttp.$inject = ['$http'];
    nawApp.app.factory('ServiceHttp', nawApp.ServiceHttp.Factory);
}

Consuming the method is a little different too then. It could look like this:

serviceHttp.exampleFunction()    
    .then(function (result) {
        console.log(result);        
      }, function() {
        console.log("error");
      });       
    };

You can read more about the promises here: https://docs.angularjs.org/api/ng/service/$q

Shouldn't use a deferred when you already have a promise chain going : github.com/petkaantonov/bluebird/wiki/…

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