WebApi无法读取传入的POST字符串参数，也就是调用这个WebApi的代码中不论给code0传入什么字符串，WebApi读到的code0都是空值。希望各位专家能够给与指点迷津！
也就是执行完string code = code0;后，code无法获取code0的值，也就是code0根本就没有传进来。
我的WebApi代码如下：
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
namespace expressApi.Controllers
{
[Route("api/[controller]")]
[ApiController]
public class SurfaceController : ControllerBase
{
public List<TechnicalRequirement> TechnicalRequirements = new List<TechnicalRequirement>();
[HttpPost("PostSurface")]
public IActionResult Surface([FromForm] string code0)
{
string code = code0;
if (TechnicalRequirements == null)
{
return NotFound();
}
return Ok(TechnicalRequirements);
}
}
我用于测试调用这个WebApi的代码如下（初步认为不会是下面的代码的问题，因为别人用JAVA写的程序一样无法传入参数）：
```c#
string strUri = requestUri;
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(strUri);
request.Method = "POST";
//request.ContentType = "text/plain";
request.ContentType = "application/x-www-form-urlencoded";//form值的代码，只要修改req.ContentType = "application/x-www-form-urlencoded//application/json
string paraUriCoded = json;
byte[] payload;
payload = System.Text.Encoding.UTF8.GetBytes(paraUriCoded);
request.ContentLength = payload.Length;
Stream writer;
try
{
writer = request.GetRequestStream();
}
catch (Exception ex)
{
return ex.ToString();
}
writer.Write(payload, 0, payload.Length);
writer.Close();
HttpWebResponse response;
try
{
response = (HttpWebResponse)request.GetResponse();
}
catch (WebException ex)
{
response = ex.Response as HttpWebResponse;
}
Stream s = response.GetResponseStream();
StreamReader sRead = new StreamReader(s);
string postContent = sRead.ReadToEnd().ToString();
sRead.Close();
return postContent;
```
