how to prevent duplicated $http requests in AngularJS app? - angularjs

Question

I need to prevent sending the same request repeatedly to API before the previous request will give the response. I have found out some solutions. But, I don't want to disable the button while waiting for response because I have more API calls in my app.
I really need to do something in my $provider .config() .I found a way here(http://blog.codebrag.com/post/57412530001/preventing-duplicated-requests-in-angularjs).
But I need more clarification code. Any kind of reference about this is welcome.

Answer 1

Lets say you have $http in your controller.js file.
Many request to server
$http.get('/link/to/file.php');
Just one request to server, no matter how many times you will call this method:
$http.get('/link/to/file.php', {cache: true});
Example:
(function() {
'use strict';
angular
.module('yourModuleName')
.controller('DashboardCtrl', DashboardCtrl);
DashboardCtrl.$inject = ['$scope'];
function DashboardCtrl($scope) {
$scope.get = function () {
$http.get('/link/to/file.php', {cache: true}).then(function(response) {
// it will do GET request just once
// later you will get the same response from cacheFactory
})
}
}
}());

Answer 2

I would like to complement #VikasChauhan answer, however I do not have enough reputation to comment on his answer.
His code works great for me, except the part where he returns null. That causes Angular to throw a bunch of errors all over.
Instead of null, I simply reject the request:
return $q.reject(request);
Here's my function:
$httpProvider.interceptors.push(['$injector', '$q', function interceptors($injector, $q) {
return {
// preventing duplicate requests
request: function request(config) {
var $http = $injector.get('$http');
var _config = angular.copy(config);
delete _config.headers;
function isConfigEqual(pendingRequestConfig) {
var _pendingRequestConfig = angular.copy(pendingRequestConfig);
delete _pendingRequestConfig.headers;
return angular.equals(_config, _pendingRequestConfig);
}
if ($http.pendingRequests.some(isConfigEqual)) {
return $q.reject(request);
}
return config;
}
};
}
]);
Hope this helps other people.

Answer 3

You can create a function to cancel the first http request, when calling the another one on the button click.
Here is a reference that uses $q.defer() function that helped me on a similar issue:
http://odetocode.com/blogs/scott/archive/2014/04/24/canceling-http-requests-in-angularjs.aspx

Answer 4

In my project, i was facing this problem. I found a very useful working solution here
And implemented it inside the config:
function config($routeProvider, $httpProvider) {
$httpProvider.interceptors.push(['$injector', function interceptors($injector) {
// Manually injecting dependencies to avoid circular dependency problem
return {
// preventing duplicate requests
'request': function request(config) {
var $http = $injector.get('$http'),
copiedConfig = angular.copy(config);
delete copiedConfig.headers;
function configsAreEqual(pendingRequestConfig) {
var copiedPendingRequestConfig = angular.copy(pendingRequestConfig);
delete copiedPendingRequestConfig.headers;
return angular.equals(copiedConfig, copiedPendingRequestConfig);
}
if ($http.pendingRequests.some(configsAreEqual)) {
debugger;
return null;
}
return config;
}
}
}
]);
}