How to refresh / invalidate $resource cache in AngularJS

Keep the boolean and get the $http cache:

var $httpDefaultCache = $cacheFactory.get('$http');

Then you can control it like any another cache made with $cacheFactory, a usage instance provided below:

$httpDefaultCache.remove(key);
// Where key is the relative URL of your resource (eg: /api/user/current/51a9020d91799f1e9b8db12f)