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Angular 2/4 - Is it possible to initialize a provider only after a promise is resolved?

In my provider's constructor I have something like:
constructor(
public http: Http
) {
this.http.get("api.php").toPromise().then(res=>this.res = res.json());
}
However, I only want this provider to be accessible only after this.http.get("api.php").toPromise() is resolved. Everything else should be the same as a normal provider, such as the way it is injected. Is it possible? How?

What I did with AngularJS :
initialize you attribute with var = $q.defer()
when you meet the requested value, use var.resolve(value)
And until you get the value, you can postpone treatments using var.promise.then(function (data) { ... })
Whole code of a service :
angular.module('myApp')
.service('myService', ['$http', '$q', function ($http, $q) {
s.myVar = $q.defer();
s.loadMyVar = function () {
$http({
method: 'GET',
url: "somewhere"
}).then(function successCallback(response) {
s.myVar.resolve(response.data);
});
};
s.getMyVar = function () {
return s.myVar.promise.then(function (data) {
return data;
});
};
return s;
}]);

How to store data in angularjs application?

Hi I am developing my first Angularjs application. I want to save data in Angularjs application for later use(I have used localstorage in jquery before).
For example, I will make ajax call and i will get some data, Lets say below example,
$http.post('http://192.168.0.213:1234/api/VerifyUser', $stateParams.pageList).then(function (response) {
alert(response.data);
another example, After succesfull login i will get some ID in response and i want to preserve this data all over the application. This ID i may use in all subsequent ajax calls.
I will get some data in response and i want to make use that data in other controllers as well. Is there any way i can do this? any help would be appreciated. Thank you.

you can store it in factory like below,
After your Ajax call
$http.post('http://192.168.0.213:1234/api/VerifyUser', $stateParams.pageList).then(function (response) {
alert(response.data)
SomeFactory.setData(response.data);
};
SomeFactory
(function () {
'use strict';
angular
.module('app.myApp')
.factory('SomeFactory', SomeFactory);
SomeFactory.$inject = [];
function SomeFactory() {
var someData;
var factory = {
setData: setData,
getData: getData
};
function setData(data) {
someData = data;
}
function getData() {
return someData;
}
return factory;
}
})();
In your Controllers
inject your factory to your controller and then getdata
(function () {
'use strict';
angular
.module('app.login')
.controller('LoginController', LoginController);
LoginController.$inject = ['SomeFactory'];
function LoginController(SomeFactory) {
var vm = this;
vm.someVariable = SomeFactory.getData();
console.log(vm.someVariable); // logs your data
}
})();

Sharing data between controllers can be achieved with the following options :
Factory
Service
Then you can inject the service across the controllers and use the data whenever you need.
app.service('myService', function($http) {
this.getJSON = function() {
$http.post('http://192.168.0.213:1234/api/VerifyUser', $stateParams.pageList).then(function(response) {
return response.data;
});
};
});
In Controller:
app.controller('myController', function($scope, myService) {
myService.getJSON().then(function(data) {
$scope.myData = data;
console.log(data);
});
});
DEMO

Use Service to store the data and get the data in another controller later on.
When you inject a Service, it's the same service in every controller - so you can access the properties and methods in that service all over.
https://docs.angularjs.org/guide/services
Example:
.service('YourService', function(){
var YourService = {};
YourService.yourvar = '';
return YourService;
})
.controller('controller1', function($scope, YourService){
YourService.yourvar = 'blah';
})
.controller('controller2', function($scope, YourService){
$scope.currentYourVar = YourService.yourvar;
})

Returning response from factory to controller in Angular

I have a factory that request user data via an api call:
angular.module('MyApp')
.factory('UserApi', function($auth,Account){
return {
getProfile: function()
{
Account.getProfile()
.then(function(response){
return response.data; ----> returning json data ok!!
});
}
}
});
But when i call the function in controller, it return me undefined
myApp.controller('AppCtrl', function($rootScope,$state,$window,$document,$scope,$filter,$resource,cfpLoadingBar,$translate,UserApi){
$scope.user = function(){
UserApi.getProfile().then(function(data){
$scope.currentUser = data;
})
}
console.log($scope.user()); ----> undefined
});
account factory:
angular.module('MyApp')
.factory('Account', function($http){
return {
getProfile: function(){
return $http.get('/api/me');
}
}
});
The error that log in console is TypeError: Cannot read property 'then' of undefined
EDIT
The only available solution is to set the response.data to $rootScope.user in which the data will be available across the controllers.
angular.module('MyApp')
.factory('UserApi', function($auth,Account,$rootScope){
return {
getProfile: function()
{
Account.getProfile()
.then(function(response){
$rootScope.user = response.data; ----> returning json data ok!!
});
return $rootScope.user;
}
}
});

First of all getProfile method should return a promise (not undefined like it's doing in your code):
angular.module('MyApp')
.factory('UserApi', function($auth,Account){
return {
getProfile: function()
{
return Account.getProfile()
.then(function(response) {
return response.data;
});
}
}
});
then in controller you should use then callback:
myApp.controller('AppCtrl', function ($rootScope, $state, $window, $document, $scope, $filter, $resource, cfpLoadingBar, $translate, UserApi) {
$scope.user = function () {
UserApi.getProfile().then(function (data) {
$scope.currentUser = data;
console.log($scope.currentUser);
})
};
});
Also make sure you understand the difference between synchronous and asynchronous code, and why console.log($scope.user()) makes no sense in this case: response if not yet available when you try to log it. Instead you provide a callback to be called when data has come.

You are trying to return the data after the request is completed successfully. But, since this is an ajax call we don't know when it will be completed (Basically, runs on a different thread.). There are two ways you can resolve this.
1 - Just return the call like so.
angular.module('MyApp')
.factory('UserApi', function($auth,Account){
return {
getProfile: function(){
return Account.getProfile(); // return call and resolve in controller.
}
}
});
2 - You can use promise ($q)
angular.module('MyApp')
.factory('UserApi', function($auth,Account, $q){
return {
getProfile: function(){
var deferred = $q.defer();
Account.getProfile()
.success(function(data){
deferred.resolve(data);
});
return deferred.promise; // just return the promise
}
}
});
and in your controller just have the following.
myApp.controller('AppCtrl', function($rootScope,$state,$window,$document,$scope,$filter,$resource,cfpLoadingBar,$translate,UserApi){
$scope.user = function(){
UserApi.getProfile().then(function(data){
$scope.currentUser = data;
console.log($scope.currentUser);
});
}
});

EDITED:
You get undefined. Because:
there isn't return in $scope.user
your console.log($scope.user($scope.user()) works only initial time.
there is time delay for getting data from UserApi.getProfile()
Also, your codes have some mistakes:
I can suggest that:
Don't use your console.log($scope.user()) initial time.
Or, You should get all data initial time when factory created. Then, you use UserApi.data in your controller.(But, there is time delay. You may get success data, if request return response before from loading of your controller).
.
angular.module('MyApp')
.factory('UserApi', function ($auth, Account) {
var data;
Account.getProfile().then(function (response) {
data = response.data;
});
return {
data: data
}
});
myApp.controller('AppCtrl', function ($rootScope, $state, $window, $document, $scope, $filter, $resource, cfpLoadingBar, $translate, UserApi) {
console.log(UserApi.data);
});

AngularJS $scope.foo is set with service, but later on in the same controller undefined

I have a service which calls API and gets json response. I inject this service into my controller and try to set $scope.tank variable with this received data. When I try to use this variable later on (in the same controller!) it is undefined. But the funny thing is that data is displayed in the front-end.
I've looked all over stackoverflow and I can not figure this out. I have created a plunker example - http://plnkr.co/edit/DkFNE8E9897dSF19eaU9?p=preview
My service:
appServices.service('TankService', function($q, $http) {
var data, deferred = $q.defer();
return {
init: function(id) {
var defer = $q.defer();
$http.get(options.api.base_url, { cache: 'true'})
.success(function(response) {
data = response;
deferred.resolve(data);
});
},
// return promise
getData: function() {
return deferred.promise;
}
};
});
I call my data in controller like this:
appControllers.controller('TankViewCtrl', ['$rootScope', '$scope', '$q', '$routeParams', '$location', '$sce', '$route', 'TankService',
function TankViewCtrl($rootScope, $scope, $q, $routeParams, $location, $sce, $route, TankService) {
var id = $routeParams.tank_id;
$scope.id = id;
$scope.tank = [];
// call our data
TankService.init(id);
TankService.getData().then(function(data){
$scope.tank = data;
});
// why is this undefined?
console.log($scope.tank);
}
]);
Thank in advance for your help!

HTTP calls are asynchronous requests.
You're asking your controller to display the result of the request without making sure you had an answer beforehand. That's why you get undefined.
Use :
TankService.getData().then(function(data){
$scope.tank = data;
console.log($scope.tank);
});

How to pass data to different controller in my case?

I am trying to create factory for the restful services.
I need to make service calls. First call's data will be used to get the second calls data.
My problem is I don't know how to transfer data from one controller to another controller.
Is there a better way to do my codes?
Here are my codes...
var app = angular.module('myApp', []);
//getting init data via service
app.factory('myService', function($http) {
var myService = {
async: function() {
var promise = $http.get('test/test.json').then(function (response) {
return response.data;
});
return promise;
}
};
return myService;
});
//retrieve data
app.controller('testCtrl', function(myService, $scope, $http) {
myService.async().then(function(data) {
$scope.data = data
//using retrieve data to get another piece of data
vay first = data[0].employee[0];
})
$http({
url: "test?" + first +'.json',
method: "GET",
}).success(function(secondData) {
$scope.secondData=secondData //How do I pass data to my secondCtrl?
})
})
app.controller('secondCtrl', function($scope) {
// I need to be able to get the secondData from testCtrl.
console.log($scope.secondData)
})
Thanks for the help!

Why don't you store the data as an object in the service itself, then both controllers depend on the service and have access to the data. Like this:
app.factory('myService', function($http) {
var that = this;
var myService = function($http) {
this.set = function(url) {
var promise = $http.get(url).then(function (response) {
that.data = promise.data;
});
return promise;
}
};
return new myService($http);
});
Then your controller sets and gets the data in the way
app.controller('testCtrl', function(myService, $scope, $http) {
myService.set('someurl').then(function() {
$scope.data = myservice.data;
//using retrieve data to get another piece of data
vay first = data[0].employee[0];
myservice.set('someOtherUrl?data='+first);
})
app.controller('secondCtrl', function($scope, myservice) {
//the data object on the myservice function has been changed on the first controller and we can reasonably expect the data we need. If these 2 controllers coexist in the same space and time we can wrap this in a $watch service
console.log(myservice.data)
});
$watch service example
app.controller('secondCtrl', function($scope, $watch, myservice) {
$watch('myservice.data', function(newval, oldval) {
console.log(newval);
}, true)
//I will only log the newvalue of myservice.data when the data has changed. the last true argument is a neccesity so that angular will compare the values within the object
});

You could either extend 'myService' to contain the response data, using it in both controllers, or you could create another service for sharing data between them.
Both solutions would look similar, but here is what the second option (new service) might look like:
Factory
.factory('SharedService', function(){
var shared = {
data: ''
}
return shared;
})
This factory could act as just a place to store some data. In fact, if all you'd like to do is share data, you could just use a value provider. But a factory you could later extend with a more complex data structure and methods.
In your controllers, just inject the service and, optionally, set it to a scope variable:
Controller 1
.controller('FirstController', function($scope, SharedService){
$scope.shared = SharedService;
$scope.shared.data = 'foo';
})
$scope.shared now references the service object. If you were to do the same in the other controller, they could both read/write to that same object:
Controller 2
.controller('SecondController', function($scope, SharedService){
$scope.shared = SharedService;
console.log($scope.shared.data); // 'foo' if called after first ctrl set it
})
Demo