How to save and read Cookie in Asp.net Mvc - asp.net-mvc

Question

I save my cookie as the following code:
public static void SetCookie(string key, string value, int expireDay = 1)
{
var cookie = new HttpCookie(key , value);
cookie.Expires = DateTime.Now.AddDays(expireDay);
HttpContext.Current.Response.Cookies.Add(cookie);
}
The cookie values when stored are as follows:
Read Cookie:
public static string GetCookie(string key)
{
string value = string.Empty;
var cookie = HttpContext.Current.Request.Cookies[key];
if (cookie != null)
{
if (string.IsNullOrWhiteSpace(cookie.Value))
{
return value;
}
value = cookie.Value;
}
return value;
}
The problem is that when reading the cookie, all the values are empty according to the image below:

Answer 1

The maximum size of a cookie is 4kb.

Answer 2

Actually you should read cookies from request header; not response!

Answer 3

The problem is here: HttpContext.Current.Response.Cookies.AllKeys.Contains(key).
You need to read it from the request. And write the changes to the response.
Here's a simpler working example, that simply prints "Hey!", and appends an exclamation on each GET:
public class IndexModel : PageModel
{
public string CookieValue = "Hey!";
private const string COOKIE_KEY = "HEY_COOKIE";
public void OnGet()
{
Request.Cookies.TryGetValue(COOKIE_KEY, out string? actualValue);
if (actualValue is not null) CookieValue = actualValue + "!";
// Only required since we're changing the cookie
// TODO: set the right cookie options
Response.Cookies.Append(COOKIE_KEY, CookieValue, new CookieOptions { });
}
}
#page
#model IndexModel
<h1>#Model.CookieValue</h1>
Also, while debugging things over HTTP, it's useful to also look at Chrome's network tab.

Answer 4

Your problem is that you used HttpContext.Current.Response. Instead of this, you should declare a parameter in the SetCookie method like this: HttpContext context, then in the controller, when you call the method, you have to send HttpContext controller property as an argument.
public static void SetCookie(HttpContext context, string key, string value, int expireDay = 1)
{
var cookie = new HttpCookie(key , value);
cookie.Expires = DateTime.Now.AddDays(expireDay);
context.Response.Cookies.Add(cookie);
}
In the controller:
SetCookie(HttpContext, yourKey,yourValue)
You also should change your GetCookie method like this:
public static string GetCookie(HttpContext context,string key)
{
string value = string.Empty;
var cookie = context.Request.Cookies[key];
if (cookie != null)
{
if (string.IsNullOrWhiteSpace(cookie.Value))
{
return value;
}
value = cookie.Value;
}
return value;
}