Angularjs how to cancel resource promise when switching routes

Solution 1:

First of all, I decided I needed to use $http since I couldn't find any solution that used $resource, nor could I get it to work on my own.

So here's what my factory turned into, based on @Sid's answer here, using the guide at http://www.bennadel.com/blog/2616-aborting-ajax-requests-using-http-and-angularjs.htm

.factory('AllSites',function($http,$q){

    function getSites(categoryID) {

        // The timeout property of the http request takes a deferred value
        // that will abort the underying AJAX request if / when the deferred
        // value is resolved.
        var deferredAbort  = $q.defer();

        // Initiate the AJAX request.
        var request = $http({
            method: 'get',
            url: 'api/categorySites/'+categoryID,
            timeout: deferredAbort.promise
        });

        // Rather than returning the http-promise object, we want to pipe it
        // through another promise so that we can "unwrap" the response
        // without letting the http-transport mechansim leak out of the
        // service layer.
        var promise = request.then(
            function( response ) {
                return( response.data );
            },
            function() {
                return( $q.reject( 'Something went wrong' ) );
            }
        );

        // Now that we have the promise that we're going to return to the
        // calling context, let's augment it with the abort method. Since
        // the $http service uses a deferred value for the timeout, then
        // all we have to do here is resolve the value and AngularJS will
        // abort the underlying AJAX request.
        promise.abort = function() {
            deferredAbort.resolve();
        };

        // Since we're creating functions and passing them out of scope,
        // we're creating object references that may be hard to garbage
        // collect. As such, we can perform some clean-up once we know
        // that the requests has finished.
        promise.finally(
            function() {
                promise.abort = angular.noop;
                deferredAbort = request = promise = null;
            }
        );

        return( promise );
    }

    // Return the public API.
    return({
        getSites: getSites
    });

});

Then, in my controller (route 'A' from my problem):

var allSitesPromise = AllSites.getSites(categoryID);

$scope.$on('$destroy',function(){
    allSitesPromise.abort();
});

allSitesPromise.then(function(allSites){
    // do stuff here with the result
}

I wish the factory wasn't so messy, but I'll take what I can get. However, now there's a separate, related issue Here where, though the promise was cancelled, the next actions are still delayed. If you have an answer for that, you can post it there.

Solution 2:

There is a similar question with the answer "How to cancel $resource requests".

While it does not address the question exactly it gives all ingredients to cancel resource request when route is switched:

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8" />
  <title>Cancel resource</title>
  <script src="//ajax.googleapis.com/ajax/libs/angularjs/1.3.9/angular.js"></script>
  <script src="//ajax.googleapis.com/ajax/libs/angularjs/1.3.9/angular-resource.js"></script>
  <script>
angular.module("app", ["ngResource"]).
factory(
  "services",
  ["$resource", function($resource)
  {
    function resolveAction(resolve)
    {
      if (this.params)
      {
        this.timeout = this.params.timeout;
        this.params.timeout = null;
      }

      this.then = null;
      resolve(this);
    }

    return $resource(
      "http://md5.jsontest.com/",
      {},
      {
        MD5:
        {
          method: "GET",
          params: { text: null },
          then: resolveAction
        },
      });
  }]).
controller(
  "Test",
  ["services", "$q", "$timeout", function(services, $q, $timeout)
  {
    this.value = "Sample text";
    this.requestTimeout = 100;

    this.call = function()
    {
      var self = this;

      self.result = services.MD5(
      {
        text: self.value,
        timeout: $q(function(resolve)
        {
          $timeout(resolve, self.requestTimeout);
        })
      });
    }
  }]);
  </script>
</head>
<body ng-app="app" ng-controller="Test as test">
  <label>Text: <input type="text" ng-model="test.value" /></label><br/>
  <label>Timeout: <input type="text" ng-model="test.requestTimeout" /></label><br/>
  <input type="button" value="call" ng-click="test.call()"/>
  <div ng-bind="test.result.md5"></div>
</body>
</html>

How it works

$resource merges action definition, request params and data to build a config parameter for an $http request.
a config parameter passed into an $http request is treated as a promise like object, so it may contain then function to initialize config.
action's then function may pass timeout promise from params into the config.

Please look at "Cancel Angularjs resource request" for details.

Angularjs how to cancel resource promise when switching routes

Solution 1:

Solution 2:

How it works

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