I'm doing some small exercises to learn AngularJS, trying to understand how to work with promises at the moment.
In the following exercise, I'm trying to get some data async. I can see the data in the console.log but the promise is returned NULL.
GET /entries 200 OK
Promise is resolved: null
Anyone experienced can give me some advice to understand what I'm doing wrong ? Thanks for looking!
angular.module('questions', [])
.config(function($routeProvider) {
$routeProvider
.when('/', {
controller: 'MainCtrl',
resolve: {
'MyServiceData': function(EntriesService) {
return EntriesService.promise;
}
}
})
})
.service('EntriesService', function($http) {
var entries = null;
var promise = $http.get('entries').success(function (data) {
entries = data;
});
return {
promise: promise,
all: function() {
return entries;
}
};
})
.controller('MainCtrl', ['$scope', 'EntriesService', function($scope, EntriesService) {
console.log('Promise is resolved: ' + EntriesService.all());
$scope.title = "Q&A Module";
$scope.entries = EntriesService.all() || [];
$scope.addMessage = function() {
$scope.entries.push({
author: "myAuthor",
message: $scope.message
});
};
}]);
/****** Thanks everyone for your help so far *****/
After taking the advice of #bibs I came up with the following solution, that's clear using ngResource:
angular.module('questions', ['ngResource'])
.factory('EntriesService', function($resource){
return $resource('/entries', {});
})
.controller('MainCtrl', ['$scope', 'EntriesService', function($scope, EntriesService) {
$scope.title = "Q&A Module";
$scope.entries = [];
EntriesService.query(function(response){
$scope.entries = response;
});
$scope.addMessage = function() {
$scope.entries.push({
author: "myAuthor",
message: $scope.message
});
};
}]);
You should access the data in the callback. Since entries maybe empty before the data arrives, the all() function is not quite useful in this case.
Try this, you should be able to chain then() method to synchronously get data.
.service('EntriesService', function ($http) {
var services = {
all: function () {
var promise = $http.get('entries').success(function (data) {
entries = data;
}).error(function (response, status, headers, config) {
//error
});
return promise;
},
someOtherServices: function(){
var promise = ....
return promise;
}
return services;
}
});
$scope.entries = [];
EntriesService.all().then(function(data){
$scope.entries = data;
});
If you want the data returned by the server to be immediately reflected in your view:
.service('EntriesService', function($http) {
var entries = [];
var promise = $http.get('entries').success(function (data) {
for (var i = 0; i < data.length; i++) {
entries[i] = data[i];
}
});
return {
promise: promise,
all: entries
};
})
.controller('MainCtrl', ['$scope', 'EntriesService', function($scope, EntriesService) {
$scope.title = "Q&A Module";
$scope.entries = EntriesService.all;
$scope.addMessage = function() {
$scope.entries.push({
author: "myAuthor",
message: $scope.message
});
};
You may want to check out $resource to do this for you: http://docs.angularjs.org/api/ngResource.$resource
Related
I created an angular factory for $http service. I am getting the response and able to use the same in the controller but the problem is, when i check the network tab in the browser, the http request is made twice
Factory:
app.factory('myService', function ($http, $q) {
var deferred = $q.defer();
var responseData = null;
var obj = {};
obj.getData = function(){
$http.get('test.json').success(function(response){
responseData = response;
deferred.resolve(responseData);
}).error(function(response){
deferred.reject(responseData);
});
return deferred.promise;
}
obj.myData = function(){
return responseData;
}
return obj;
});
Controller:
app.controller('myController', function($scope,myService){
myService.getData().then(function(){
$scope.myDetails = myService.myData();
});
});
what's wrong in my approach. Please provide me a solution
The way you are making your caching scenario is quite complicated and not really helpful. How do you know if data has already been loaded?
Maybe you can create a simple Caching Service to handle your caching at a single point (nr of code lines will go down).
angular.module("YourApp").factory("CachingService", [
"$q",
"$http",
function ($q, $http,) {
var cache = {};
return {
getFromCache: getFromCache
};
function getFromCache(url) {
var deferred = $q.defer();
if (cache[url]) {
deferred.resolve(cache[url]);
} else {
return $http.get(url).then(function (result) {
cache[url] = result;
return result;
});
}
return deferred.promise;
}
}
]);
And then, you simply call it inside your other service :
angular.module("YourApp").factory("myService", [
"CachingService",
function(CachingService){
return {
getData: getData
};
function getData(){
return CachingService.getFromCache("test.json");
}
}
]);
And then, inside your controller :
app.controller('myController', function($scope,myService){
myService.getData().then(function(result){
$scope.myDetails = result.Data;
});
});
you can return $http not deferred.promise
I'm trying to make two API calls in parallel using $q.all, and return both of their responses as one to the controller, and when I break on the return lines for each promise inside the hash, they return the expected data, but it all seem to break when it reaches $q.all. This is all in a ui-router state, and I'm using resolve to supposedly provide the corresponding controller with the data from $q.all
It was originally written in Coffeescript, but here it is in Javascript:
resolve: {
content: [
'APIService', function($q, $timeout, APIService) {
var firstPromise, secondPromise, promises;
firstPromise = $q.defer();
secondPromise = $q.defer();
promises = {
firstPromise: APIService.get('/some/api/call').then(function(response) {
return response;
}),
secondPromise: APIService.get('/another/api/call').then(function(response) {
return response;
})
};
$.blockUI();
$timeout(function() {
firstPromise.resolve('firstPromise');
secondPromise.resolve('secondPromise');
}, 1000);
$q.all(promises).then(function(responses) {
$.unblockUI();
return responses;
});
return false;
}
]
}
Please help? I'm using Angular 1.3.15
content:[ should actually be :
resolve: {
content: function(){
// <create promise array>
return $q.all(promises);
}
}
It's hard to recreate your logic, but this example works well and hope will help (Angular 1.3)
angular.module('myApp',[])
.controller('MyCtrl', function ($scope, $q, $timeout) {
$scope.name = "Superhero"
var prom1 = $q.defer();
var prom2 = $q.defer();
var promises = {
prom1: prom1.promise,
prom2: prom2.promise
};
$timeout(function () {
prom1.resolve('prom1');
prom2.resolve('prom2');
}, 1000);
$q.all(promises).then(function (responces) {
$scope.prom1 = responces.prom1;
$scope.prom2 = responces.prom2;
});
});
http://jsfiddle.net/ugja9gth/1/
Example with real $http
http://jsfiddle.net/Evgeniy_D/ugja9gth/2/
I am working on an application in which I am calling a webservice and get a response. I am using that response in 2 different modules. In first module I am using as it is and in second module I am doing some formatting and using it.
I created a service for getting data as follows
angular.module('myApp').factory('getData',function($http, $q, restURLS) {
var getData= {};
getData.getTree = function () {
var deferred = $q.defer();
$http.get(restURLS.getTree).
success(function (data) {
deferred.resolve(data);
}).error(deferred.reject);
return deferred.promise;
};
return getData;
});
for Serving response I created another factory as follows
angular.module('myApp').factory('tree', function($http, $q, restURLS, getData, messages) {
var tree= {};
tree.hierarchy = {};
tree.formattedHierarchy = {};
function formatHierarchy(data) {
//some formatting on data.
tree.formattedHierarchy = data;
}
function callTree() {
getData.getTree()
.then(function (data) {
tree.hierarchy = angular.copy(data);
formatHierarchy(data);
}).catch(function () {
//error
});
}
callTree();
return tree;
});
I want to call webservice only once. if data is loaded then factory('tree') should send the data to controller. Otherwise factory('tree') should call webservice and load data.
you need something to know if you got your tree or not... try this:
(UPDATED)
var myApp = angular.module('myApp', ['ngMockE2E'])
// FAKE HTTP CALL JUST FOR EMULATE
.run(function ($httpBackend) {
var tree = [{
node1: 'abcde'
}, {
node2: 'fghi'
}];
$httpBackend.whenGET('/tree').respond(function (method, url, data) {
return [200, tree, {}];
});
})
// YOUR HTTP SERVICE
.factory('getData', function ($http, $q) {
return {
getTree: function () {
var deferred = $q.defer();
$http.get("/tree").
success(function (data) {
deferred.resolve(data);
}).error(deferred.reject);
return deferred.promise;
}
}
})
.factory('TreeFactory', function ($http, $q, getData) {
var tree = {};
var updated = false;
tree.hierarchy = {};
tree.formattedHierarchy = {};
function formatHierarchy(data) {
//some formatting on data.
tree.formattedHierarchy = data;
}
return {
callTree: function() {
if(!updated){
console.log("making http call");
return getData.getTree().then(function (data) {
tree.hierarchy = angular.copy(data);
formatHierarchy(data);
updated = true;
return tree;
}).
catch (function () {
//error
});
}else{
console.log("tree already loaded");
var deferred = $q.defer();
deferred.resolve(tree);
return deferred.promise;
}
}
};
}).controller("MyCtrl", ['$scope', 'TreeFactory', function ($scope, TreeFactory) {
$scope.updateTree = function(){
TreeFactory.callTree().then(function(data){
$scope.tree = data;
});
};
}]);
HTML
<div ng-app="myApp" ng-controller="MyCtrl" ng-init="updateTree()">tree: {{tree}} <br><button ng-click="updateTree()">UPDATE TREE</button></div>
CHECK THE FIDDLE
I am trying to use an ng-repeat inside of an ng-view, but it is not pulling in the data. I was reading on the forums that I could use a factory, but I don't think using a service would be acceptable since the data for my $scope uses $routeParams to query its data.
var myApp = angular.module('myApp', ['ngRoute']);
myApp.config(['$routeProvider',
function($routeProvider) {
$routeProvider.
when('/:name', {
templateUrl: 'welcome.html',
controller: 'myController'
}).
otherwise ({
redirectTo: '/'
});
}]);
myApp.controller('myController', ['$scope', '$routeParams', '$q', function($scope, $routeParams, $q) {
var pls = users($q, $routeParams.name);
$scope.sBP = pls;
}]);
function users($q, name) {
var playersDFD = $q.defer();
var players = new Array();
var GameScore = Parse.Object.extend("GameScore");
var query = new Parse.Query(GameScore);
query.equalTo("playerName", name);
query.find({
success: function (results) {
for (var i in results) {
sPlayer = new player(results[i].get("playerName"), results[i].get("score"), results[i].get("cheatMode"));
players.push(sPlayer);
}
playersDFD.resolve(players);
},
error: function (error) {
alert('error');
playersDFD.reject(data);
}
});
return playersDFD.promise
.then(function (results) {
return results;
})
.catch(function (error) {
alert(error.message);
});
};
function player(name, score, cheatm){
this.name = name;
this.score = score;
this.cheatm = cheatm;
};
And the view:
<p ng-repeat="s in sBP">
{{ s.name }}
</p>
Let your users function return the promise rather than trying to resolve it, this ends up with code that is a lot easier to follow and will give the consumers of the user function control of what to do once you receive a response. For example.
function users($q, name) {
var playersDFD = $q.defer();
var players = new Array();
var GameScore = Parse.Object.extend("GameScore");
var query = new Parse.Query(GameScore);
query.equalTo("playerName", name);
query.find({
success: function (results) {
for (var i in results) {
sPlayer = new player(results[i].get("playerName"), results[i].get("score"), results[i].get("cheatMode"));
players.push(sPlayer);
}
playersDFD.resolve(players);
},
error: function (error) {
alert('error');
playersDFD.reject(data);
}
});
return playersDFD.promise;
}
And then use the users function and handle then itself.
users($q, $routeParams.name).then(function (response) {
$scope.sBP = response;
}, function (error) {
// handle error.
});
Also I would recommend breaking out users into it's own service to inject $q rather than pass it in.
Hope that helps.
I am trying to use promise and service to set the data from http request.
I have something like this
angular.module('myApp').controller('productController', ['$scope', 'testService',
function($scope, testService) {
testService.getProducts().then(function(products){
console.log(products);
})
//getFirstProduct is trigger by ng-click user action.
$scope.getFirstProduct = function(){
var t = testService.getFirstProduct();
console.log(t);
}
}
]);
angular.module('myApp').service('testService', ['Product', '$q',
function(Product, $q) {
var products, firstProduct;
var getFirstProduct = function(){
return firstProduct;
}
var setFirstProduct = function(product) {
firstProduct = product;
}
var getProducts = function() {
var deferred = $q.defer();
//Product is a $resource object to send an http request
Product.query({
id: 123
}, function(result) {
setFirstProduct(result.first);
deferred.resolve(classes);
});
return deferred.promise;
}
return {
setFirstProduct: setFirstProduct,
getProducts: getProducts,
getFirstProduct: getFirstProduct
};
}
]);
I need to be able to get First product but I am not sure how to fix this. Can anyone help me about it? Thanks a lot
I see a number of errors in the code such as missing semicolons, mistyped variable/function names, and that setProducts was clobbering its variable.
Also, added $q, as mentioned by #manube
The following should work better:
angular.module('myApp').controller('productController', ['$scope', 'testService',
function($scope, testService) {
testService.getProducts().then(function(products){
console.log(products);
})
//getFirstProduct is trigger by ng-click user action.
$scope.getFirstProduct = function(){
var t = testService.getFirstProduct();
console.log(t);
}
}
]);
angular.module('myApp').service('testService', ['Product', '$q',
function(Product, $q) {
var products, firstProduct;
var getFirstProduct = function(){
return firstProduct;
}
var setFirstProduct = function(product) {
firstProduct = product;
}
var getProducts = function() {
var deferred = $q.defer();
//Product is a $resource object to send an http request
Product.query({
id: 123
}, function(result) {
setFirstProduct(result.first);
deferred.resolve(classes);
});
return deferred.promise;
}
return {
setFirstProduct: setFirstProduct,
getProducts: getProducts,
getFirstProduct: getFirstProduct
};
}
]);