Flushing the ASP.NET Output cache using code

When looking to speed up content that will be served from an ASP.NET MVC controller, one of the options I evaluate is the built in Output caching mechanism.  Output caching is great because it’s easy to setup, easy to maintain and it can give a big improvement for a small amount of code.

Sometimes, the cached item will need to be flushed (and regenerated / recached).   The built in mechanisms for handling this – using cache expiration, or varying the cached output by one of many parameters – handle most use cases pretty easily.

But other times I need to expire the Output cache programatically, and it’s not entirely obvious how to do this, so I have documented it, here:

//  Get the url for the action method:
var staleItem = Url.Action("Action", "YourController", new
{
    Id = model.Id,
    area = "areaname";
});

//  Remove the item from cache
Response.RemoveOutputCacheItem(staleItem);

Where “Action” and “YourController” are the names of the Action method and controller that have the [OutputCache] attribute. Notice that this example also passes route data (the Id and the area “areaname”) – this is how you’ll need to specify any parameters to the action method to build a complete url in Url.Action.

Note: that you can use this code from any part of your application – you can expire the output cache of one controller/method from a completely different controlller/method.

Also, you’ll need to remember to add the Location=OutputCacheLocation.Server parameter to the OutputCache attribute, like this:

[OutputCache(Location=System.Web.UI.OutputCacheLocation.Server, Duration = 300, VaryByParam = "Id")]