C# HttpClient：如何在 POST 请求中发送查询字符串

Question

这是 POST 请求，它有效。

curl -X POST --header 'Accept: application/json' 

'http://mywebsite.com/api/CompleteService?refId=12345&productPrice=600'

如何使用C# => HttpClient => client.PostAsync() 方法发送这个请求？ 两种方法都试过了，都失败了。

方法 1（失败，响应 404）

string url = "http://mywebsite.com/api/CompleteService";
string refId = "12345";
string price= "600";
string param = $"refId ={refId}&productPrice={price}";
HttpContent content = new StringContent(param, Encoding.UTF8, "application/json");
HttpResponseMessage response = client.PostAsync(url, content).Result;

这只有在 API 接受请求正文而不是查询字符串时才有效。

方法 2（失败，响应 404） https://stackoverflow.com/a/37443799/7768490

var parameters = new Dictionary<string, string> { { "refId ", refId }, { "productPrice", price} };
var encodedContent = new FormUrlEncodedContent(parameters);
HttpResponseMessage response = client.PostAsync(url, encodedContent)

Answer 1

显然，所有尝试过的方法都没有将参数放在URL! 中。您在以下网址发帖

"http://mywebsite.com/api/CompleteService"

但是，有些东西是可行的

string url = "http://mywebsite.com/api/CompleteService?";
string refId = "12345";
string price= "600";
string param = $"refId={refId}&productPrice={price}";
HttpContent content = new StringContent(param, Encoding.UTF8, "application/json");

将参数附加到 URL 并获取响应的正文，使用：

  try   
  {
     HttpResponseMessage response = await client.PostAsync(url + param, content);
     response.EnsureSuccessStatusCode();
     string responseBody = await response.Content.ReadAsStringAsync();
     Console.WriteLine(responseBody);
  }
  catch(HttpRequestException e)
  {
     Console.WriteLine("Message :{0} ",e.Message);
  }