How can I remove the output cache on a per-user basis in ASP.NET MVC?

Question

I'm using VaryByCustom to create an output cache on a per-browser and per-user basis:

[OutputCache(Duration = 6000, VaryByParam = "*", VaryByCustom="browser;userName")]

(I've overridden GetVaryByCustomString() to make this work.)

I need to be able to remove a single user's output cache, without invalidating the output cache of different users, if possible. I've read about HttpResponse.RemoveOutputCacheItem() , but that works by removing the output cache based on path. Is there any way to do this based on the VaryByCustom string?

Answer 1

You can take the advantage of VaryByCustom property in [OutputCache] by overriding HttpApplication.GetVaryByCustomString and check HttpContext.Current.User.IsAuthenticated.

This is what I will create in Global.asax.cs file:

public override string GetVaryByCustomString(HttpContext context, string custom)
    {
        if (custom == "UserName")
        {
            if (context.Request.IsAuthenticated)
            {
                return context.User.Identity.Name;
            }
            return null;
        }

        return base.GetVaryByCustomString(context, custom);
    }

And then use it in OutputCache attribute:

[OutputCache(Duration = 10, VaryByParam = "none", VaryByCustom = "UserName")]
public ActionResult Profiles()
{
    //...
}

but be careful that the username should be immutable in this case!

Answer 2

为什么不让用户参与参数，然后通过VaryByParam为每个用户。

Answer 3

perhaps use

Response.Cache.SetVaryByCustom(string custom);

in an ActionFilter the you can build up the string including browser version and user