I am currently trying to store a $http JSON request to a variable in a factory and then retrieve the value of that variable in a controller.
Currently all I receive back is undefined. I imagine the AJAX request isn't finished running before the function gets called. I am new to Angular so trying to grab any basic concepts I can and helpful knowledge.
app.factory('typiCode', function($http) {
var jsonService = {
async: function() {
var promise = $http.get('https://jsonplaceholder.typicode.com/posts/1')
.then(function(response) {
console.log(response);
return response.data;
})
return promise;
}
};
return jsonService;
});
app.controller("getJson", function($scope, typiCode) {
$scope.returnedData = typiCode.jsonService;
$scope.logResults = function() {
var theData = $scope.returnedData;
console.log(theData);
}
});
<button ng-click="logResults()">Launch data</button>
Thank you in advance!
Your typiCode factory returns your jsonService object. So you should be calling typiCode.async() somewhere in your code.
You could do, for example, like this in your controller:
app.controller("getJson", function($scope, typiCode) {
typiCode.async()
.then(function(data) {
$scope.returnedData = data;
})
$scope.logResults = function() {
var theData = $scope.returnedData;
console.log(theData);
}
});
Related
I have this array I am getting through the following method:
var url= *url defined here*;
$scope.ViewProfile = function () {
$http.get(url)
.success(function (response) {
$scope.ProfileList = response;
$scope.FavNumbers = $scope.ProfileList[0].FavNumbers;
})
.error(function () {
});
}
I am required to edit the Fav Numbers list on the UI. and post it back to another url through http post url method. What I am stuck is with the concept of asynchronous calls, due to which I am unable to retrieve the favorite numbers list to be available for editing. Please help!
I have tried a method of using promises as follows:
app.factory('myService', function($http) {
var myService = {
async: function(url) {
var promise = $http.get(url).then(function (response) {
console.log(response);
return response.data;
});
// Return the promise to the controller
return promise;
}
};
return myService;
});
In my controller I am doing:
angular.module('JuryApp').controller('mycontroller', ['myService', function (myService) {
myService.async(url).then(function(d) {
$scope.data = d;
});
app.controller('MainCtrl', function( myService,$scope) {
// Call the async method and then do stuff with what is returned inside our own then function
myService.async().then(function(d) {
$scope.data = d;
});
});
But I keep getting the error 'd is not defined'. It keeps giving an error of some sort, where the debugger goes into an infinite loop or something.
You are overcomplicating it, I think. Async calls are actually pretty simple:
You're service:
app.factory("myService", ["$http", function($http) {
var MyService = {
getData: function(url) {
return $http.get(url); //$http returns a promise by default
}
};
return MyService;
})];
Your controller:
angular.module('JuryApp').controller('mycontroller', ['myService', function (myService) {
$scope.FavNumbers = [];
var url = "http://my.api.com/";
myService.getData(url).then(function(response) {
$scope.FavNumbers = response.data[0].FavNumbers;
});
}]);
That's all that you need to do.
I need to grab some data from my db through an API and make it accessible throughout my Angular app. I understand that Services are good for storing data to be accessed from multiple controllers. However, in the following code I end up with a new $hhtp.get() each time just to get the same data.
Service:
.factory('Playlist', ['$http', function($http) {
var playlist = {};
playlist.getPlaylist = function() {
return $http.get('api/playlist.php')
.then(function (response) {
var data = response.data;
return data;
})
}
return playlist;
}])
Controllers:
.controller('ScheduleCtrl', ['$http', 'Playlist', function($http, Playlist) {
var self = this;
Playlist.getPlaylist()
.success(function(playlist) {
self.playlist_id = playlist.id;
fetchItems();
})
var fetchScheduleItems = function() {
return $http.get('api/schedule.php/'+self.playlist_id).then(
function(response) {
if (response.data === "null") {
console.log("No items");
} else {
self.items = response.data;
}
}, function(errResponse) {
console.error('Error while fetching schedule');
});
};
}])
.controller('PlaylistItemCtrl', ['$http', 'Playlist', function($http, Playlist) {
var self = this;
Playlist.getPlaylist()
.success(function(playlist) {
self.playlist_id = playlist.id;
fetchItems();
})
var fetchPlaylistItems = function() {
return $http.get('api/schedule.php/'+self.playlist_id).then(
function(response) {
if (response.data === "null") {
console.log("No items");
} else {
self.items = response.data;
}
}, function(errResponse) {
console.error('Error while fetching schedule');
});
};
}])
Is there a way to store the Playlist ID without pinging 'api/playlist.php' from every controller?
Update
Here's a Plunkr based on Abhi's answer: http://plnkr.co/edit/or9kc4MDC2x3GzG2dNeK?p=preview
As you can see in the console, it's still hitting the server several times. I've tried nesting CachedData.save() differently, but it doesn't seem to apply.
I would say store your data locally (CachedData factory - rename it to something that makes sense) and inside your getPlaylist method, before doing http call, check CachedData to see if your data is present and if not, then do the http call.
The code will be something like the below. I have just written it free-hand, so there may be some errors, but you get the picture.
.factory('Playlist', ['$http', 'CachedData', function($http, CachedData) {
var playlist = {};
playlist.getPlaylist = function() {
if (CachedData.data) {
// return cached data as a resolved promise
} else
return $http.get('api/playlist.php')
.then(function (response) {
var data = response.data;
cachedData.save(data);
return data;
})
}
return playlist;
}])
// CachedData factory
.factory('CachedData', function() {
var _data;
var cachedData = {
data: _data,
save: function(newData) {
_data = newData;
}
};
return cachedData;
})
EDIT: Also Remove fetchPlaylistItems from the controller and put it in a factory. The controller is just a glue between your viewmodel and view. Put all your business logic, http calls in a service.
EDIT: I have setup a plunk for you here. I hope it helps.
EDIT: John, the reason you are seeing two server calls is because they are from different controllers ManiCtrl1 and MainCtrl2. By the time, the getPlaylist method from MainCtrl2 is called, the first http request didn't get the chance to finish and save the data. If you add a timeout to MainCtrl2 before calling your service method, you will see that the data is retrieved from cache. See this updated plunk for a demo.
This will be more useful in an app with multiple views, where you don't want to reload data when navigating back to a view. (Ideally, depending on the type of data you are caching, you will have some expiry time after which you would want to reload your data).
You could do some pre validation when calling that method.
var playlist = {};
playlist.playlist = [];
playlist.getPlaylist = function () {
if (playlist.playlist.length <= 0) { //or some lodash _.isEmpty()
$http.get('api/playlist.php')
.then(function (response) {
playlist.playlist = response.data;
})
}
return playlist.playlist;
};
Hope it helps!
In my angular module I wrote a generic http handler for all my ajax requests.'
I was expecting that I could use the service across controllers, but my problem is the promise seems to be global.
Once ControllerOne uses the mapi_loader service, when I load AnotherController (by ng-click="go('/$route_to_load_another_controller')"), AnotherController is loaded a promise that has already returned from ControllerOne even though the URL they fetch are totally different.
So I guess my question is how do I write a service I could use across controllers? Do I really need to write a separate service for each controller where their only difference in code is the URL passed for $http.jsonp?
angular.module('myAppControllers',[])
.service('mapi_loader', ['$http', function($http) {
var promise;
var myService = {
fetch: function(url) {
if ( !promise ) {
promise = $http.jsonp(url)
.then(function (response) {
return response.data.nodes;
});
}
return promise;
}
};
return myService;
}])
.controller('ControllerOne', ['$scope', 'mapi_loader', function ($scope, mapi_loader) {
mapi_loader
.fetch("http://host.com/mapi_data_for_controller_one?callback=JSON_CALLBACK")
.then(function(data) {
$scope.useme = data;
});
}])
.controller('AnotherController', ['$scope', 'mapi_loader', function ($scope, mapi_loader) {
mapi_loader
.fetch("http://host.com/mapi_data_for_another_controller?callback=JSON_CALLBACK")
.then(function(data) {
$scope.useme = data;
});
}])
;
try something like this
angular.module('myAppControllers',[])
.service('mapi_loader', function($http) {
var alreadyLoading = {};
return {
fetch: function(url) {
if ( url in alreadyLoading ) {
return alreadyLoading[url];
}
return alreadyLoading[url] = $http.jsonp(url)
.then(function (response) {
delete alreadyLoading[url];
return response.data.nodes;
});
}
};
})
.controller('ControllerOne', function ($scope, mapi_loader) {
...
})
.controller('AnotherController', function ($scope, mapi_loader) {
...
});
I'm trying to make a single $http request to get one of my JSON files and use the data across all my controllers.
I saw on egghead.io how to share data across multiple controllers, and I've also read this StackOverflow question: "Sharing a variable between controllers in angular.js".
However, the answers there don't use the $http module. When using $http, the controllers don't have the data to work on, and by the time the response is received it's already too late.
I then found the method $q.defer and this question on StackOverflow: "AngularJS share asynchronous service data between controllers"
The solution posted there works fine, BUT it has two issues:
Each controller will trigger the $http request to obtain the same data already used in another controller; and,
If I try to manipulate the data received I have a then function.
Below you can see my code:
controllers.js
'use strict';
/* Controllers */
function appInstallerListCtrl($scope, Data) {
$scope.apps = Data;
}
function appInstallerDetailCtrl($scope, $routeParams, Data) {
$scope.appId = $routeParams.appId;
$scope.apps = Data;
console.log($scope.apps); // <-- then function
console.log(Data); // <-- then function with $vv data returned but I can't access it
for (var i in $scope.apps) // <--- no way, baby!
console.log(i);
}
app.js
var app = angular.module('appInstaller', []);
app.factory('Data', function($http, $q) {
var defer = $q.defer();
$http.get('apps.json').then(function(result) {
defer.resolve(result.data.versions.version);
});
return defer.promise;
});
app.config(['$routeProvider', function($routeProvider) {
$routeProvider.
when('/app', {templateUrl: 'partials/app-list.html', controller: appInstallerListCtrl}).
when('/app/:appId', {templateUrl: 'partials/app-detail.html', controller: appInstallerDetailCtrl}).
otherwise({redirectTo: '/app'});
}]);
What I'd like to have is that when launching the app, the $http request will be performed and the response will be used throughout the app across all controllers.
Thanks
I like to store my data in the service, and return a promise to the controllers, because usually you need to deal with any errors there.
app.factory('Data', function($http, $q) {
var data = [],
lastRequestFailed = true,
promise;
return {
getApps: function() {
if(!promise || lastRequestFailed) {
// $http returns a promise, so we don't need to create one with $q
promise = $http.get('apps.json')
.then(function(res) {
lastRequestFailed = false;
data = res.data;
return data;
}, function(res) {
return $q.reject(res);
});
}
return promise;
}
}
});
.controller('appInstallerListCtrl', ['$scope','Data',
function($scope, Data) {
Data.getApps()
.then(function(data) {
$scope.data = data;
}, function(res) {
if(res.status === 500) {
// server error, alert user somehow
} else {
// probably deal with these errors differently
}
});
}]);
Any callbacks that are registered after a promise has been resolved/rejected will be resolved/rejected immediately with the same result/failure_reason. Once resolved/rejected, a promise can't change (its state). So the first controller to call getApps() will create the promise. Any other controllers that call getApps() will immediately get the promise returned instead.
Since you are using a promise, to access the data returned by promise use the callback syntax
function appInstallerDetailCtrl($scope, $routeParams, Data) {
$scope.appId = $routeParams.appId;
Data.then(function(returnedData) {
$scope.apps=returnedData;
console.log($scope.apps);
for (var i in $scope.apps)
console.log(i)
});
}
Make sure this
defer.resolve(result.data.versions.version);
resolve returns array, for the above code to work. Or else see what is there in data and ajust the controller code.
I found the way not sure weather it is a best approach to do it or not.
In HTML
<body ng-app="myApp">
<div ng-controller="ctrl">{{user.title}}</div>
<hr>
<div ng-controller="ctrl2">{{user.title}}</div>
</body>
In Javascript
var app = angular.module('myApp', []);
app.controller('ctrl', function($scope, $http, userService) {
userService.getUser().then(function(user) {
$scope.user = user;
});
});
app.controller('ctrl2', function($scope, $http, userService) {
userService.getUser().then(function(user) {
$scope.user = user;
});
});
app.factory('userService', function($http, $q) {
var promise;
var deferred = $q.defer();
return {
getUser: function() {
if(!promise){
promise = $http({
method: "GET",
url: "https://jsonplaceholder.typicode.com/posts/1"
}).success(function(res) {
data = res.data;
deferred.resolve(res);
})
.error(function(err, status) {
deferred.reject(err)
});
return deferred.promise;
}
return deferred.promise;
}
}
});
This will exactly make only 1 HTTP request.
My issue was that I didn't want to wait for resolve before loading another controller because it would show a "lag" between controllers if the network is slow. My working solution is passing a promise between controllers via ui-router's params and the data from promise can be loaded asynchronously in the second controller as such:
app.route.js - setting the available params to be passed to SearchController, which shows the search results
.state('search', {
url: '/search',
templateUrl: baseDir + 'search/templates/index.html',
controller: 'SearchController',
params: {
searchPromise: null
}
})
landing.controller.js - controller where the user adds search input and submits
let promise = SearchService.search(form);
$state.go('search', {
searchPromise: promise
});
search.service.js - a service that returns a promise from the user input
function search(params) {
return new Promise(function (resolve, reject) {
$timeout(function() {
resolve([]) // mimic a slow query but illustrates a point
}, 3000)
})
}
search.controller.js - where search controller
let promise = $state.params.searchPromise;
promise.then(r => {
console.log('search result',r);
})
The Setting: I want to have a service that multiple controllers can query for data pulled using $http. The initial solution was to use promises as suggested here.
The Problem: Each time a controller queries the service, the service then returns an $http promise, resulting in multiple queries that just pulls the same data from a remote server, over and over again.
A Solution: The service function returns either data or a promise like below. And it is up to the controller to check and act accordingly.
app.factory('myService', function($http) {
var items = [];
var myService = {
getItems: function() {
// if items has content, return items; otherwise, return promise.
if (items.length > 0) {
return items;
} else {
var promise = $http.get('test.json').then(function (response) {
// fill up items with result, so next query just returns items.
for(var i=0;i<response.data.length;i++){
items.push(response.data[i]);
}
return items;
});
// Return the promise to the controller
return promise;
}
};
return myService;
});
So when a controller needs that data, the controller just does something like this:
app.controller('MainCtrl', function( myService,$scope) {
var promiseOrData = myService.async();
// Check whether result is a promise or data.
if ( typeof promiseOrData.then === 'function'){
// It's a promise. Use then().
promiseOrData.then( function(data ){
$scope.data = data;
});
} else {
// It's data.
$scope.data = data;
}
});
So the question is: Is there a better way of doing this? With many controllers, this method would have a lot of duplicate code. Ideally, the controllers will just query the service for data directly.
Thanks!
$http returns a promise, we can use that instead of creating a new one with $q. Once the promise is resolved, we can keep returning it.
.factory('myService', ['$http','$q', function($http, $q) {
var items = [];
var last_request_failed = true;
var promise = undefined;
return {
getItems: function() {
if(!promise || last_request_failed) {
promise = $http.get('test.json').then(
function(response) {
last_request_failed = false;
items = response.data;
return items;
},function(response) { // error
last_request_failed = true;
return $q.reject(response);
});
}
return promise;
},
};
}])
In your controller:
myService.getItems().then(
function(data) { $scope.data = data; }
);
Create your own promise that resolves to either the cached data or the fetched data.
app.factory('myService', function($http, $q) {
var items = [];
var myService = {
getItems: function() {
var deferred = $q.defer();
if (items.length > 0) {
//resolve the promise with the cached items
deferred.resolve(items);
} else {
$http.get('test.json').then(function (response) {
// fill up items with result, so next query just returns items.
for(var i=0;i<response.data.length;i++){
items.push(response.data[i]);
}
//resolve the promise with the items retrieved
deferred.resolve(items);
},function(response){
//something went wrong reject the promise with a message
deferred.reject("Could not retrieve data!");
});
}
// Return the promise to the controller
return deferred.promise;
};
return myService;
});
Then consume the promise in your controller.
app.controller('MainCtrl', function( myService,$scope) {
var promiseOrData = myService.getItems();
promiseOrData.then( function(data){
$scope.data = data;
},
function(data){
// should log "Could not retrieve data!"
console.log(data)
});
});