javascript - Retry request with $http interceptor

Question

I'm sure there is an easy way to do what I want, I just cant wrap my head around it. How can I get the http interceptor in angular to retry a request if it fails? I imagine I would have to build some sort of promise in the request right? Then in the response I would have to check whether the response was an error and if so, do the promise? How is that done? I have been trying to adapt the example here: http://docs.angularjs.org/api/ng.$http

The reason I am trying to use an interceptor is because I need to add the token and a few other things to the request url, as well as some things to handle xdr's.

Answer 1

Here's a $http interceptor that (immediately) replays timed out request(s) (i.e. response status 0). There were two non-obvious (to me!) elements to constructing this example:

1. How to call $http from within the interceptor - simply adding $http to the dependency list didn't work as angular complains of a circular dependency
2. How to reference the original request from the response object in order to retry it

This answer addresses both topics but is more involved so I include a simplified version below.

joinApp.factory('httpResponseErrorInterceptor',function($q, $injector) {
  return {
    'responseError': function(response) {
      if (response.status === 0) {
        // should retry
        var $http = $injector.get('$http');
        return $http(response.config);
      }
      // give up
      return $q.reject(response);
    }
  };
});

joinApp.config(function($httpProvider) {
  $httpProvider.interceptors.push('httpResponseErrorInterceptor');
});

In your actual implementation, you would likely want more sophisticated http response code processing, a limit to the number of times you retry, etc.