ng-resource Conditional/bypass Cache

[k-funk]

This is a feature request.

I'd really like if I could bypass the cache, conditionally, from a $resource class. I've put cache: true for each of my resource actions that I want to reload from memory/cache, but I'd like to bypass the cache during certain calls. Most of my application resides in angular, but occasionally a user will take an action that requires refreshing an endpoint.

I don't need a complex cache, just an occasional hit to the server for fresh data, as decided in a controller.

IE:

var User = $resource(
  '/user/:userId',
  {userId:'@id'},
  {get: {method: 'GET', cache: true}}
);
User.get({userId:123});
User.get({userId:123, cache: true}); // same as above
User.get({userId:123, cache: false}); // don't use the cache, this one time.

This stackoverflow question was asked, which a fix this feature would be a better solution for.

[gkalpak]

Just wanted to point out that it is fairly easy to implement a separate, "non-cache" method and call that one whenever you need to bypass the cache. E.g.:

app.factory('User', function ($resource) {
    return $resource('/user/:userId', {userId: '@id'}, {
        get:      {method: 'GET', cache: true},
        getFresh: {method: 'GET', cache: false}
    });
});

Demo fiddle

Additionally, you could "internalize" it to your service, creating a service method (e.g. useCache(true/false)) that swaps the two methods, so you always call the same method from the outside.

[k-funk]

While these would work, I think it's still adding too much complexity to the resource service.

Solution 1: for each method, I'd need an additional method, potentially doubling the lines of code, or having to cleverly store my interceptors/transformers in a variable outside the resource definition, and put them in later in order to reuse the code (works, but makes it harder for people to read).

Solution 2: when you say swap the two methods, do you mean

var temp = userResource.get;
userResource.get = userResource.getFresh;
userResource.getFresh = temp;

for each action defined on my resource that I want to be using the cache?

If so, that seems rather hacky, and then the method names are then in flux as to what they mean/should be doing (and tough to debug down the road). I'd be more apt to use $cacheFactory.get('$http').removeAll(); in my controller for the sake of cleanliness/readability.

Is there not a way to pass a var in while calling an instance method? The params object seems to get parsed, and pass along the key/vals to the Router. Couldn't cache: false be passed along as well? If I were using $http.get() I'd be able to decide if I wanted to use the cache at the point of the call. I think resource should have the same feature.

[damiendube]

Would this addition force a refresh and then update the cache? Or by passing "cache: false" it wouldn't update the cache with the returned value?

I think we need a way to tell ngResource to execute the query but to still update the cache with the returned result.

[k-funk]

@damiendube, ideally, it would just force the use of ajax, and the response would be handled as normal—putting it in the cache. The point being just to override the cache-reads based on conditions in the controller.

Agreed. I'm not sure there would even be a use case for not updating the cache with one of these cache-read bypasses.

[dbautistav]

As a temporal workaround, see this stackoverflow entry.

[roidayan]

I like this solution with an interceptor in stack overflow

[isometriq]

Thanks @roidayan
The "cachedResource" example is brilliant indeed!

[Narretz]

I'm going to close this issue as there exist enough APIs to implement this behavior.