c# - 更改已存在的 cookie 的 cookie 值

Question

我有一个名为 SurveyCookie 的 cookie。像这样创建:

var cookie = new HttpCookie("SurveyCookie");
cookie.Values["surveyPage"] = "1";
cookie.Values["surveyId"] = "1";
cookie.Values["surveyTitle"] = "Definietly not an NSA Survey....";
cookie.Values["lastVisit"] = DateTime.UtcNow.ToString();
cookie.Expires = DateTime.UtcNow.AddDays(30);
Response.Cookies.Add(cookie);

这很好用。现在，当我想像这样更改“surveyPage”值时，问题就来了。

下面将创建一个新的 cookie，这不是我想要的。

int cookieValue = Convert.ToInt32(Request.Cookies["SurveyCookie"]["surveyPage"]) + 1;
Response.Cookies["SurveyCookie"]["surveyPage"] = cookieValue.ToString();

然后我尝试了下面的这段代码，它也不起作用。当应该是 2 时，surveyPage 仍然是 1。

Request.Cookies["SurveyCookie"]["surveyPage"] = cookieValue.ToString(); 

由于以上都不起作用，什么会改变surveyPage的cookies值？

Answer 1

来自 ASP.NET Cookies Overview :

You cannot directly modify a cookie. Instead, changing a cookie consists of creating a new cookie with new values and then sending the cookie to the browser to overwrite the old version on the client.

你可以试试这个:

HttpCookie cookie = Request.Cookies["SurveyCookie"];
if (cookie == null)
{
    // no cookie found, create it
    cookie = new HttpCookie("SurveyCookie");
    cookie.Values["surveyPage"] = "1";
    cookie.Values["surveyId"] = "1";
    cookie.Values["surveyTitle"] = "Definietly not an NSA Survey....";
    cookie.Values["lastVisit"] = DateTime.UtcNow.ToString();
}
else
{
    // update the cookie values
    int newSurveyPage = int.Parse(cookie.Values["surveyPage"]) + 1;
    cookie.Values["surveyPage"] = newSurveyPage.ToString();
}

// update the expiration timestamp
cookie.Expires = DateTime.UtcNow.AddDays(30);

// overwrite the cookie
Response.Cookies.Add(cookie);