C# HttpClient - 如果在请求标头中将 UseCookies 设置为 false，是否可以从响应中获取 cookie？

Question

I know you can get cookies by adding a CookieContainer in the request handler.

However, the following post request fails unless I set UseCookies to false:

static CookieContainer cookies = new CookieContainer();    

  var clientHandler = new HttpClientHandler
    {
       //Original Apporach - this fails the POST request 
       // UseCookies = true,
       // CookieContainer = cookies,

       //I had to do this
        UseCookies = false,
    };
    var client = new HttpClient(clientHandler);
    var request = new HttpRequestMessage
    {
        Method = HttpMethod.Post,
        RequestUri = new Uri("*redacted*"),
        Headers =
        {
            { "cookie", "SampleCookie" },
        },
        Content = new FormUrlEncodedContent(new Dictionary<string, string>
        {
            { "Provider", "Email" },
            { "Code", "12345" },
            { "RememberMe", "False" },
            { "RememberBrowser", "false" },
            { "__RequestVerificationToken", "SampleToken" },
        }),
    };
    using (var response = await client.SendAsync(request))
    {
        response.EnsureSuccessStatusCode();
        var body = await response.Content.ReadAsStringAsync();
        Console.WriteLine(body);
    }

Not very knowledgeable with HTTP request to be honest. Is my original approach failing because I'm setting the cookie manually?

Answer 1

The reason for the request failing might depend on many things - like authentication and other headers needed, without knowing the specifics of what you're trying to access it's hard to tell what's causing it. Here's a simple example that shows how to make a request to Google front page and get all the cookies into the container and print them out in a Console app:

static void Main(string[] args)
{
    var uri = new Uri("https://google.com");
    var cookies = new CookieContainer();
    var handler = new HttpClientHandler();
    handler.CookieContainer = cookies;

    using (var client = new HttpClient(handler))
    {
        var result = client.GetAsync(uri).Result;
    }

    foreach (Cookie cookie in cookies.GetCookies(uri))
    {
        var print = $"cookie name: {cookie.Name}\ncookie value: {cookie.Value}\n";
        Console.WriteLine(print);
    }
}

Answer 2

many people still recommend UseCookies = false to send/override custom cookies, this is wrong.

UseCookies = false is to disable request/response cookies container, I know if I do this I can send custom header Cookie but the downside I cannot read Response Cookie inside cookie container or even response headers.

The right way to override this, is to set the cookie inside the CookieContainer

CookieContainer cookies = new CookieContainer();
// add your custom cookie here
Cookie customCookie = new Cookie("cookieKey", "cookieValue" "/", "example.com");
cookies.Add(customCookie);

var clientHandler = new HttpClientHandler
{
    CookieContainer = cookies,
    //UseCookies = false, // no need this
};

// no need to write
// Headers = { { "cookie", "cookieKey=cookieValue" } }