I have a cookie called "g" with values "y" or "n"
I set it like this:
Response.Cookies("g").Value = "y"
Response.Cookies("g").Expires = DateTime.Now.AddHours(1)
I change it like this:
Request.Cookies("g").Value = "n"
and I try to destroy it like this
Response.Cookies("g").Expires = DateTime.Now.AddHours(-1)
The cookie gets set fine, but I cannot change its value or destroy it
Thanks!
Try deleting it this way:
if (Request.Cookies["g"] != null)
{
HttpCookie myCookie = new HttpCookie("g");
myCookie.Expires = DateTime.Now.AddDays(-1);
Response.Cookies.Add(myCookie);
}
I think if you try creating the cookie and adding it to the Response like this it should work.
You want to add in a new cookie to the response that has the same name. Also I recommend going back a day and not just an hour.
To change the value of the cookie do this:
if (Request.Cookies["g"] != null)
{
HttpCookie myCookie = new HttpCookie("g");
myCookie.Expires = DateTime.Now.AddHours(1);
myCookie.Value = "n";
Response.Cookies.Add(myCookie);
}
The important thing to note with these examples is that we are observing the read-only request collection to see what is already in there, and then we are making changes or deleting by adding a new cookie to replace the one that was there before.
You cannot change the Request cookie, you can only "re-set" it in your response. Hence, you need to set the same cookie in your Response.
However the Expire-trick should work, but sometimes the DST (daylight saving time) might confuse the browser. Have you tried using a very old DateTime (like, 1970) in order to expire the cookie?
Related
Here is my code for removing the cookie:
HttpCookie c1 = HttpContext.Current.Request.Cookies["id"];
c1.Expires = DateTime.Now.AddDays(-1d);
c1.Value = "0";
Response.Cookies.Add(c1);
var test = Request.Cookies["id"].Value; //Test to check if cookie was deleted or at least changed the value.
HttpContext.Current.Response.Cookies.Clear();
HttpContext.Current.Session.Abandon();
Now when i debug this and reach the var = test line of code the cookie value is equal to 0. which is good, but when i move to another page, suddenly all the changes have been revoked, the id cookie returns to its last value. I tried refreshing the page, but nothing works.
I just cant get rid of these cookies...
I create some cookies in logon.aspx.cscodebehind thatc read and contain user info from DB with data reader .
HttpCookie UID = new HttpCookie("ID");
Response.Cookies["UID"].Value = Recordset[0].ToString();
Response.Cookies.Add(UID);
HttpCookie UName = new HttpCookie("Username");
Response.Cookies["Username"].Value = Recordset[3].ToString();
Response.Cookies.Add(UName);
HttpCookie Pass = new HttpCookie("Pass");
Response.Cookies["Pass"].Value = Recordset[4].ToString();
Response.Cookies.Add(Pass);
HttpCookie Admins = new HttpCookie("Admin");
Response.Cookies["Admin"].Value = Recordset[12].ToString();
Response.Cookies.Add(Admins);
HttpCookie Mails = new HttpCookie("Emails");
Response.Cookies["Emails"].Value = Recordset[9].ToString();
Response.Cookies.Add(Mails);
Response.Redirect("../default.aspx");
when i trace the code every thing is good and data hold by cookies.
Now when i read these cookies in master page or other content page, i can't.
in other worlds the cookies not recognize by their names(or keys)
if (Request.Cookies["Username"] !=null)
{
lblWelcomeUser.Text = Server.HtmlEncode(Request.Cookies["Username"].Value);
pnlUsersNavigation.Visible = true;
LoginMenu.Visible = false;
RegisterMenu.Visible = false;
lblWelcomeUser.Text = Server.HtmlEncode(Request.Cookies["Username"].Value);
//lblWelcomeUser.Text = Request.Cookies["Username"].Value.ToString();
if (Request.Cookies["Admin"].Value.ToString()=="True")
{
lblWelcomeUser.Text = "WELCOME ADMIN";
// Show Menu that is only for Admin
}
where is the problem in this code?
It appears that you might be overwriting the cookie with a good value, with a new empty cookie.
// new cookie created - empty
HttpCookie UName = new HttpCookie("Username");
// new cookie created with a value
Response.Cookies["Username"].Value = Recordset[3].ToString();
// overwrite new cookie with value with new empty cookie
Response.Cookies.Add(UName);
Create the cookie, set the value, then add the cookie to the response.
HttpCookie UName = new HttpCookie("Username");
UName.Value = Recordset[3].ToString();
Response.Cookies.Add(UName);
Also note that as Paul Grimshaw pointed out, you can add multiple values to the same cookie.
Download Fiddler to check request/response to ensure your cookies contain the correct values and such... http://fiddler2.com/get-fiddler
Also be careful about Man-in-the-middle attacks. Storing usernames and passwords in plain text is not such a good idea to begin with.
This doesn't look like a very secure way of securing access to your application. Try looking at ASP.NET membership.
Otherwise try setting an expiry date. Also, as this example shows, you may want to store all the above info in one cookie:
HttpCookie myCookie = new HttpCookie("UserSettings");
myCookie["UID"] = Recordset[0].ToString();
myCookie["Username"] = Recordset[3].ToString();
//...etc...
myCookie.Expires = DateTime.Now.AddDays(1);
Response.Cookies.Add(myCookie);
Also, from MSDN:
By default, cookies are shared by all pages that are in the same
domain, but you can limit cookies to specific subfolders in a Web site
by setting their Path property. To allow a cookie to be retrieved by
all pages in all folders of your application, set it from a page that
is in the root folder of your application and do not set the Path
property. If you do not specify an expiration limit for the cookie,
the cookie is not persisted to the client computer and it expires when
the user session expires. Cookies can store values only of type
String. You must convert any non-string values to strings before you
can store them in a cookie. For many data types, calling the ToString
method is sufficient. For more information, see the ToString method
for the data type you wish to persist.
I have some asp.net pages that read and write cookie values. During the life cycle of a page it may update the cookie value and then need to read it again further in the code. What I've found is that it's not getting the latest value of the cookie until a page refresh. Is there a way around this? Here's the code I'm using to set and get the values.
public static string GetValue(SessionKey sessionKey)
{
HttpCookie cookie = HttpContext.Current.Request.Cookies[cookiePrefix];
if (cookie == null)
return string.Empty;
return cookie[sessionKey.SessionKeyName] ?? string.Empty;
}
public static void SetValue(SessionKey sessionKey, string sessionValue)
{
HttpCookie cookie = HttpContext.Current.Request.Cookies[cookiePrefix];
if (cookie == null)
cookie = new HttpCookie(cookiePrefix);
cookie.Values[sessionKey.SessionKeyName] = sessionValue;
cookie.Expires = DateTime.Now.AddHours(1);
HttpContext.Current.Response.Cookies.Set(cookie);
}
What you're missing is that when you update the cookie with SetValue you're writing to the Response.Cookies collection.
When you call GetValue you're reading from the Request.Cookies collection.
You need to store the transient information in a way that you access the current information, not just directly the request cookie.
One potential way to do this would be to writer a wrapper class that with rough psuedo code would be similar to
public CookieContainer(HttpContext context)
{
_bobValue = context.Request.Cookies["bob"];
}
public Value
{
get { return _bobValue; }
set {
_bobValue = value;
_context.Response.Cookies.Add(new Cookie("bob", value) { Expires = ? });
}
}
I ran into needing to do similar code just this week. The cookie handling model is very strange.
Start using Sessions to store your information, even if it's only temporary.
Cookies rely on a header being sent to the browser before the page has rendered. If you've already sent information to the client then proceed to set a cookie, you're going to see this "page refresh delay" you've described.
If it's necessary to have this value, use a session variable between the time you set the cookie and when you refresh the page. But, even then I would just recommend avoiding settings cookies so late in the processing step and try to set it as early as possible.
Is it possible to update an ASP.NET cookies value without also having to update the expiration time? I have found that if I try and update a Cookie without also updating the expiration, that cookie no longer exists. I have the following code which I am try to modify. What's the point of having an expiration, if every time the cookie value is updated, so is the expiration?
HttpCookie cookie = HttpContext.Current.Request.Cookies[constantCookie];
if (cookie == null)
cookie = new HttpCookie(constantCookie);
cookie.Expires = DateTime.Now.AddYears(1);
cookie.Value = openClose;
HttpContext.Current.Response.Cookies.Set(cookie);
The ASP.NET HttpCookie class can not initialize the Expires property upon reading in a cookie from an HTTP request (since the HTTP specification doesn't require the client to even send the Expiration value to the server in the first place). And if you don't set the Expires property before you set the cookie back in the HTTP Response, than it turns it into a session cookie instead of a persistent one.
If you really must keep the expiration, than you could set the initial expiration date as part of the cookie value, then when you read the cookie in, parse out the value and set the new expiration to match.
An example that doesn't include any other data so the cookie isn't really helpful -- you would have to serialize it somehow with the actual data you want to store:
HttpCookie cookie = HttpContext.Current.Request.Cookies[constantCookie];
DateTime expires = DateTime.Now.AddYears(1);
if (cookie == null) {
cookie = new HttpCookie(constantCookie);
} else {
// cookie.Value would have to be deserialized if it had real data
expires = DateTime.Parse(cookie.Value);
}
cookie.Expires = expires;
// save the original expiration back to the cookie value; if you want to store
// more than just that piece of data, you would have to serialize this with the
// actual data to store
cookie.Value = expires.ToString();
HttpContext.Current.Response.Cookies.Set(cookie);
I have a ASP MVC App with some seemingly simple code to save and retrieve cookies but for some reason they won't persist. The code in the controller is :
if (System.Web.HttpContext.Current.Response.Cookies["CountryPreference"] == null)
{
HttpCookie cookie = new HttpCookie("CountryPreference");
cookie.Value = country;
cookie.Expires = DateTime.Now.AddYears(1);
System.Web.HttpContext.Current.Response.Cookies.Add(cookie);
}
And to load it again :
if (System.Web.HttpContext.Current.Request.Cookies["CountryPreference"] != null)
{
System.Web.HttpContext.Current.Request.Cookies["CountryPreference"].Expires = DateTime.Now.AddYears(1);
data.Country = System.Web.HttpContext.Current.Request.Cookies["CountryPreference"].Value;
}
For some reason the cookie is always null?
The problem lies in following code:
if (System.Web.HttpContext.Current.Response.Cookies["CountryPreference"] == null)
When you try to check existence of a cookie using Response object rather than Request, ASP.net automatically creates a cookie.
Check this detailed post here: http://chwe.at/blog/post/2009/01/26/Done28099t-use-ResponseCookiesstring-to-check-if-a-cookie-exists!.aspx
Quote from the article in case the link goes down again ....
The short explanation, if you don’t
like to read the entire story
If you use code like “if
(Response.Cookies[“mycookie”] != null)
{ … }”, ASP.Net automatically
generates a new cookie with the name
“mycookie” in the background and
overwrites your old cookie! Always use
the Request.Cookies-Collection to read
cookies!
[ More detail in the article ]
In resume, don't use "Response" to read cookies, use "Request".