CODEWITHSUNDEEP
c#asp.net
k80sg
k80sg

Reputation: 2473

Clear browser cache only on logout

How can I clear browser cache only on logout, sure I can use the below:

Response.Cache.SetCacheability(HttpCacheability.NoCache);
Response.Cache.SetExpires(DateTime.UtcNow.AddHours(-1));
Response.Cache.SetNoStore();

But this particular page which is a shopping bag page is accessible by both login and non-login users. How can I set it in such a way whereby the login user is able to access this page without clearing the browser cache but Only clears it when he/she logs out so that another user will not be able to access the history contents.

I have tried the solutions here: http://www.codeproject.com/Tips/135121/Browser-back-button-issue-after-logout made some changes but still couldn't figure out how to deal with this issue.

I also cleared my session on logout as below but I understand the browser cache will still stay. 

FormsAuthentication.SignOut();
Session.Abandon();
Response.Redirect("~/");

Please advice. Thanks.

Upvotes: 3

Views: 9205

Answers (4)

uadrive
uadrive

Reputation: 1269

There is a way to do it. If you are caching a page, you can add a vary parameter. For Example

[OutputCache(Duration = 60, Location = System.Web.UI.OutputCacheLocation.Client, VaryByParam = "random")]
[CompressFilter]
public ActionResult Page(PageModel model)
{
      ...
}

In the example above, if I pass a random variable like the ticks of the current datetime object, that will prevent the cache.

Upvotes: 0

James McCormack
James McCormack

Reputation: 9934

Perhaps you are getting muddled with the difference between server and client cache?

If you set output cache on your aspx page, that's server-side cache, and you have a scenario where .NET can decide whether to send pre-cached content or not, and still apply ACL rules.

If you set cache requirements on the HTTP you return using Response.Cache, that's client-side caching. Once the browser obeys the cache rules you send here, the only opportunity you will have to retract your cache rules is the next time the browser requests the page. If you set the cache to expire tomorrow, that's the next chance you'll get to amend the caching. Assuming the browser is obeying you, by the way, of which there is no guarantee.

In short, dynamic pages should not attempt to set client-side caching if you want them to stay dynamic. In fact you should actively use techniques such as the ones you mentioned to suppress Caching on those pages at all times.

Client-side caching should really only be used to assist with performance and bandwidth on the static parts of your site.

Upvotes: 2

zeal
zeal

Reputation: 740

I am trying to solve a similar problem myself. This is just speculation, but if i could track a user specific header in my requests I was going to try using 

HttpContext.Current.Response.Cache.VaryByHeaders["login"] = true;

in the global.asax

public override string GetVaryByCustomString(HttpContext context, string arg)
{
    if (arg == "login")
    {
        return User().Name;
    }
    return base.GetVaryByCustomString(context, arg);
}

Upvotes: 0

Amir Raminfar
Amir Raminfar

Reputation: 34150

I am not a c# expert, but I am pretty sure what you have above only tells the browser to not cache the page you are on. There is no way to tell the browser to clear cache on any page. This would be a problem if there was such a way. Sounds like the solution you need is to not cache any page at all, regardless of logging out or not.

Upvotes: 5

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