How to use OutputCache for a specific argument only?

Question

I have this example of OutputCache. My problem is that I want the page to be cached only if the [id] equals to NULL. In all other cases I don't want to have cache at all.

MyController:

[OutputCache(Duration = int.MaxValue, VaryByParam = "id")]
public ActionResult Details(int id)
{}

RouteConfig:

routes.MapRoute(
    name: "edit",
    url: "edit/{id}",
    defaults: new {
        controller = "asd",
        action = "Details",
        id = UrlParameter.Optional
    }
);

score 1 · Answer 1 · answered Sep 27 '13 at 15:36

1

You can specify (and implement) the VaryByCustom parameter of OutputCacheAttribute:

MyController.cs

[OutputCache(Duration = int.MaxValue, VaryByCustom = "idIsNull")]
public ActionResult Details(int id)
{
}

Global.asax.cs

public override string GetVaryByCustomString(HttpContext context, string arg)
{
    if (arg.ToLower() == "idisnull")
    {
        return string.IsNullOrWhiteSpace(Request.QueryString["id"])
            ? string.Empty
            // unique key means it won't have a consistent value to use
            // as a cache lookup
            : ((new DateTime(1970, 1, 1) - DateTime.Now).TotalMilliseconds).ToString();
    }
}

answered Sep 27 '13 at 15:36

Brad Christie

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Thanks, but the [id] is not a query string. See edit for routing details – user1615362 Sep 27 '13 at 15:46
1

@user1615362: I don't see it defined in the route `url`, so what's the problem? – Brad Christie Sep 27 '13 at 15:59
This IsNullOrWhiteSpace(Request.QueryString["id"]) will always be true. – user1615362 Sep 27 '13 at 16:09
There are no QueryStiring params at all, I am using restful URLs and the [id] is a url segment. – user1615362 Sep 27 '13 at 17:47
1

@user1615362: once again....not according to your route. I don't see `{id}` _anywhere_ in that route, therefore it's either a POST value (in which case `Request.Form` should be used) or a GET variable (stick with `Request.QueryString`). – Brad Christie Sep 27 '13 at 17:57
Right! My bad... I have provided the wrong route. Please see the edit to the OP. – user1615362 Sep 27 '13 at 18:04

How to use OutputCache for a specific argument only?

1 Answers1