Check if Cookie Exists

Question

From a quick search on Stack Overflow I saw people suggesting the following way of checking if a cookie exists:

HttpContext.Current.Response.Cookies["cookie_name"] != null

or (inside a Page class):

this.Response.Cookies["cookie_name"] != null

However, when I try to use the indexer (or the Cookies.Get method) to retrieve a cookie that does not exist it seems to actually create a 'default' cookie with that name and return that, thus no matter what cookie name I use it never returns null. (and even worse - creates an unwanted cookie)

Am I doing something wrong here, or is there a different way of simply checking for the existance of a specific cookie by name?

Answer 1

Sometimes you still need to know if Cookie exists in Response. Then you can check if cookie key exists:

HttpContext.Current.Response.Cookies.AllKeys.Contains("myCookie")

More info can be found here.

In my case I had to modify Response Cookie in Application_EndRequest method in Global.asax. If Cookie doesn't exist I don't touch it:

string name = "myCookie";
HttpContext context = ((HttpApplication)sender).Context;
HttpCookie cookie = null;

if (context.Response.Cookies.AllKeys.Contains(name))
{
    cookie = context.Response.Cookies[name];
}

if (cookie != null)
{
    // update response cookie
}