C# HttpClient REST 请求使用 Content-Type: application/x-www-form-urlencoded

Question

I'm trying to debug this request, but I don't see what I'm doing wrong. The request is for auth info, and it's pretty simple.

curl -i -X POST \
   -H "Content-Type:application/x-www-form-urlencoded" \
   -d \
'user_name=ecommemail&password=abc123&auth_type=password' \
 'https://sample.com/api/auth/token'

Here is my latest effort.

authUrl = https://sample.com/api/auth/token;

private async Task<string> GenerateAccessObject2()
{
    HttpClientHandler handler = new HttpClientHandler() { UseDefaultCredentials = false };
    HttpClient client = new HttpClient(handler);
    client.BaseAddress = new(authUrl);
    //client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));            

    List<KeyValuePair<string, string>> postData = new List<KeyValuePair<string, string>>();
    postData.Add(new KeyValuePair<string, string>("username", "email"));
    postData.Add(new KeyValuePair<string, string>("password", "abc123"));
    postData.Add(new KeyValuePair<string, string>("auth_type", "password"));

    HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, authUrl) { Content = new FormUrlEncodedContent(postData) };
    request.Content.Headers.ContentType = new MediaTypeHeaderValue("application/x-www-form-urlencoded");

    System.Console.WriteLine(request.ToString());
    System.Console.WriteLine(request.Content);
    HttpResponseMessage response = await client.SendAsync(request);

    return response.ToString();
}

I can see in the debugger that the Content-Type header is set (client.Content.Headers). And the Accept is set too (client.Headers).

I'm not sure I'm setting the body content correctly though. I have 62 characters worth. In the request it says I have 63 set, but I can't figure out how to actually see or print the body content in the request...

The print statement gives this:

Method: POST, RequestUri: 'https://sample.com/api/auth/token', Version: 1.1, Content: System.Net.Http.FormUrlEncodedContent, Headers:
{
  Content-Type: application/x-www-form-urlencoded
}

And here is the error:

StatusCode: 500, ReasonPhrase: 'Internal Server Error', Version: 1.1, Content: System.Net.Http.HttpConnectionResponseContent, Headers:
{
  Max-Forwards: 20
  Via: 1.0 sample.com ()
  Connection: close
  X-CorrelationID: Id-d26af9610df7cc527996cde2 0
  Date: Tue, 01 Feb 2022 17:16:02 GMT
  Server: Apache
  Transfer-Encoding: chunked
  Content-Type: application/json
}

[EDIT] Another effort using MihalBy's idea.

private async Task<string> GenerateAccessObject3()
{
    HttpClientHandler handler = new HttpClientHandler() { UseDefaultCredentials = false };
    HttpClient client = new HttpClient(handler);
    client.BaseAddress = new(authUrl);
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

    string postData = HttpUtility.UrlEncode(authBody, Encoding.GetEncoding(65001));
    byte[] data = System.Text.Encoding.GetEncoding(65001).GetBytes(postData);
    ByteArrayContent content = new ByteArrayContent(data);
    content.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

    HttpResponseMessage response = await client.PostAsync(authUrl, content);

    return response.ToString();
}

This escapes the form body into something like this: "user_name%3decommemail%26password%3abc123m%26auth_type%3dpassword"

And I get a 400 Bad Request error, which I consider progress.

Answer 1

try to post using FormUrlEncodedContent

HttpClientHandler handler = new HttpClientHandler() { UseDefaultCredentials = false };
    HttpClient client = new HttpClient(handler);
    client.BaseAddress = new(authUrl);
  client.DefaultRequestHeaders.Accept.Clear();
    client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));            

var data=new Dictionary<string, string>()
    {
            {"username", "email"},
             {"password", "abc123"}
             { "auth_type", "password"}
    };

var content = new FormUrlEncodedContent(data);

var response = await client.PostAsync(authUrl, content);

if (response.IsSuccessStatusCode)
{
var stringData = await response.Content.ReadAsStringAsync();
var result = JsonConvert.DeserializeObject<object>(stringData);

}