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I want to call a particular function: GetSession() at the beginning of my application load. This function makes a $http call and get a session token: GlobalSessionToken from the server. This session token is then used in other controllers logic and fetch data from the server. I have call this GetSession()in main controller: MasterController in $routeChangeStart event but as its an asynchronous call, my code moves ahead to CustomerController before the $http response.
Here is my code:
var GlobalSessionToken = ''; //will get from server later
//Define an angular module for our app
var myApp = angular.module('myApp', ['ngRoute']);
//Define Routing for app
myApp.config(['$routeProvider', function ($routeProvider) {
$routeProvider.
when('/customer', {
templateUrl: 'partials/customer.html',
controller: 'CustomerController',
resolve: {
loadData: function($q){
return LoadData2($q,'home');
}
}
}).
otherwise({
redirectTo: '/home'
});
}]);
//controllers start here and are defined in their each JS file
var controllers = {};
//only master controller is defined in app.js, rest are in separate js files
controllers.MasterController = function($rootScope, $http){
$rootScope.$on('$routeChangeStart', function(){
if(GlobalSessionToken == ''){
GetSession();
}
console.log('START');
$rootScope.loadingView = true;
});
$rootScope.$on('$routeChangeError', function(){
console.log('ERROR');
$rootScope.loadingView = false;
});
};
controllers.CustomerController = function ($scope) {
if(GlobalSessionToken != ''){
//do something
}
}
//adding the controllers to myApp angularjs app
myApp.controller(controllers);
//controllers end here
function GetSession(){
$http({
url: GetSessionTokenWebMethod,
method: "POST",
data: "{}",
headers: { 'Content-Type': 'application/json' }
}).success(function (data, status, headers, config) {
GlobalSessionToken = data;
}).error(function (data, status, headers, config) {
console.log(data);
});
}
And my HTML has following sections:
<body ng-app="myApp" ng-controller="MasterController">
<!--Placeholder for views-->
<div ng-view="">
</div>
</body>
How can I make sure this GetSession() is always called at the very beginning of my application start and before any other controller calls and also called only once.
EDIT: This is how I added run method as per Maxim's answer. Still need to figure out a way to wait till $http call returns before going ahead with controllers.
//Some initializing code before Angular invokes controllers
myApp.run(['$rootScope','$http', '$q', function($rootScope, $http, $q) {
return GetSession($http, $q);
}]);
function GetSession($http, $q){
var defer = $q.defer();
$http({
url: GetSessionTokenWebMethod,
method: "POST",
data: "{}",
headers: { 'Content-Type': 'application/json' }
}).success(function (data, status, headers, config) {
GlobalSessionToken = data;
defer.resolve('done');
}).error(function (data, status, headers, config) {
console.log(data);
defer.reject();
});
return defer.promise;
}
536
You can't postpone the initialisation of controllers.
You may put your controller code inside a Session promise callback:
myApp.factory( 'session', function GetSession($http, $q){
var defer = $q.defer();
$http({
url: GetSessionTokenWebMethod,
method: "POST",
data: "{}",
headers: { 'Content-Type': 'application/json' }
}).success(function (data, status, headers, config) {
GlobalSessionToken = data;
defer.resolve('done');
}).error(function (data, status, headers, config) {
console.log(data);
defer.reject();
});
return defer.promise;
} );
myApp.controller( 'ctrl', function($scope,session) {
session.then( function() {
//$scope.whatever ...
} );
} );
Alternative: If you don't want to use such callbacks, you could have your session request synchronous, but that would be a terrible thing to do.
73
Even though some of the solutions here are perfectly valid, resolve property of the routes definition is the way to go, in my opinion. Writing your app logic inside session.then in every controller is a bit too much , we're used such approach too in one of the projects and I didn't work so well.
The most effective way is to delay controller's instantiation with resolve, as it's a built-in solution. The only problem is that you have to add resolve property with similar code for every route definition, which leads to code duplication.
To solve this problem, you can modify your route definition objects in a helper function like this:
function withSession(routeConfig) {
routeConfig.resolve = routeConfig.resolve || {};
routeConfig.resolve.session = ['getSessionPromise', function(getSessionPromise) {
return getSessionPromise();
}]
return routeConfig;
}
And then, where define your routes like this:
$routeProvider.when('/example', withSession({
templateUrl: 'views/example.html',
controller: 'ExampleCtrl'
}));
This is one of the many solutions I've tried and liked the most since it's clean and DRY.
25
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