c# - ASP.NET MVC Cookie Implementation

Question

I try to implement a basic cookie helper in my application. Mainly I check in base controller everytime whether or not if cookie is set. If cookie

public class MyCookie
{

    public static string CookieName {get;set;}
    public virtual User User { get; set; }
    public virtual Application App { get; set; }


    public MyCookie(Application app)
    {
        CookieName = "MyCookie" + app;
        App = app;
    }

    public void SetCookie(User user)
    {
        HttpCookie myCookie = HttpContext.Current.Request.Cookies[CookieName] ?? new HttpCookie(CookieName);
        myCookie.Values["UserId"] = user.UserId.ToString();
        myCookie.Values["LastVisit"] = DateTime.Now.ToString();
        myCookie.Expires = DateTime.Now.AddDays(365);
        HttpContext.Current.Response.Cookies.Add(myCookie);
    }

    public HttpCookie GetCookie()
    {
        HttpCookie myCookie = HttpContext.Current.Request.Cookies[CookieName];
        if(myCookie != null)
        {
            int userId = Convert.ToInt32(myCookie.Values["UserId"]);
            User user = session.Get<User>(userId);
            return user;
        }
        return null;
    }
}

if session is null I try to get from cookie or if session initialize I set cookie but I never see my cookie in browser. What is wrong?

I always start session but with userId=0 To get cookie and set session from cookie:

if (userId == 0)
{
    MyCookie myCookie = new MyCookie(_app);
    User user = cookieHelper.GetCookie();
    if (user != null)
        SessionHelper.SetSession(user);
}

Answer 1

You can't set and get a cookie in the same request. Getting a cookie gets it from the browser and it hasn't gotten it yet - Setting a cookie preps it to be sent back as part of the header when the request has completed.

You need to set the cookie and get the browser to perhaps redirect somewhere else (eg from /login to /account) then on the new request reading it will show the cookie correctly.

EDIT: In case that guess was wrong, i would also question where you are actually calling .SetCookie() as nowhere in the code you have provided are you actually calling it to create the cookie in the first place.

To debug these things i find it good to take bits of the code you assume should work, test them. For example in the page_load of a new page i entered this:

string CookieName = "bob";
long UserId = 4;
HttpCookie myCookie = HttpContext.Current.Request.Cookies[CookieName] ?? new HttpCookie(CookieName);
myCookie.Values["UserId"] = UserId.ToString();
myCookie.Values["LastVisit"] = DateTime.Now.ToString();
myCookie.Expires = DateTime.Now.AddDays(365);
HttpContext.Current.Response.Cookies.Add(myCookie);

And the cookie appeared correctly without a problem. So knowing this code actually does work we can assume the error is the function not being called or the testing/debugging you are currentlying doing is trying to set and read the cookie in the same request and failing (as i originally stated)

Either way good luck!