使用C# HttpClient发送MultipartFormDataContent传递整数值失败求助

测试Freshservice API时，RestClient能成功创建工单，但该组件会引入约20个额外依赖，因此希望改用HttpClient实现。目前HttpClient代码无法生成符合预期的工单，怀疑是status和priority参数传递问题，需要修复。

可正常运行的RestClient代码 #

var options = new RestClientOptions(_freshdeskUrl)
{
    Authenticator = new HttpBasicAuthenticator(apiKey, "X")
};
var client = new RestClient(options);

var request = new RestRequest("", Method.Post);

request.AddHeader("Accept", "application/json");
request.AddHeader("Content-Type", "multipart/form-data");
request.AddParameter("email", "tom@outerspace.com");
request.AddParameter("subject", "panel can't see files");
request.AddParameter("description", "confirm whether received");
request.AddParameter("name", "Name");
request.AddParameter("status", "2");
request.AddParameter("priority", "1");

var response = client.Execute(request);

Console.WriteLine(response);

无法正常工作的HttpClient代码 #

HttpClient httpClient = new HttpClient();
string authInfo = apiKey + ":X";
var byteArray = new UTF8Encoding().GetBytes(authInfo);
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));
MultipartFormDataContent form = new MultipartFormDataContent();
form.Add(new StringContent("panel can't see files"), "username");
form.Add(new StringContent("tom@outerspace.com"), "email");
form.Add(new StringContent("confirm whether received"), "description");
form.Add(new StringContent("2"), "status");
form.Add(new StringContent("1"), "priority");

HttpResponseMessage response = await httpClient.PostAsync(_freshdeskUrl, form);

//response.EnsureSuccessStatusCode();
httpClient.Dispose();

服务器返回响应 #

StatusCode: 201, ReasonPhrase: 'Created', Version: 1.1, Content: System.Net.Http.HttpConnectionResponseContent, Headers:
{
  Date: Wed, 09 Oct 2024 14:05:36 GMT
  Transfer-Encoding: chunked
  Connection: keep-alive
  Status: 201 Created
  Cache-Control: no-store
  Strict-Transport-Security: max-age=63072000; includeSubDomains
  X-Freshservice-Api-Version: latest=v2; requested=v2
  Pragma: no-cache
  X-Request-ID: b27d2c81-78c7-96af-8f5e-5c24fbecc271
  Location: https://nccnusersupport.freshservice.com/api/v2/tickets/21027178338
  X-Envoy-Upstream-Service-Time: 321
  X-Fw-Ratelimiting-Managed: true
  X-Ratelimit-Total: 140
  X-Ratelimit-Remaining: 139
  X-Ratelimit-Used-Currentrequest: 1
  X-Trace-Id: 00-da1535c2223299d7d3040faac49b8719-e0b5e2503d7f2fb5-01
  Nel: { "report_to": "nel-endpoint-freshservice", "max_age": 2592000, "include_subdomains": true}
  Report-To: { "group": "nel-endpoint-freshservice", "max_age": 2592000, "include_subdomains": true, "endpoints": [{"url": "https://edge-admin.us-east-1.freshedge.net/nelreports/freshservice"}]}
  Server: fwe
  Content-Type: application/json; charset=utf-8
  Expires: Wed, 13 Oct 2010 00:00:00 UTC
}}

修复方案 #

你的HttpClient代码有两个关键错误，和status、priority的类型无关（API接受字符串形式的数字参数，RestClient也是这么传的）：

1. 参数名错误：把subject参数写成了username，导致工单主题丢失
2. 缺失必要参数：没有添加name参数，这是RestClient里包含的重要参数

修复后的HttpClient代码如下：

HttpClient httpClient = new HttpClient();
string authInfo = apiKey + ":X";
var byteArray = new UTF8Encoding().GetBytes(authInfo);
httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", Convert.ToBase64String(byteArray));
// 添加Accept头，和RestClient保持一致
httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

MultipartFormDataContent form = new MultipartFormDataContent();
// 修正参数名：把username改为subject
form.Add(new StringContent("panel can't see files"), "subject");
form.Add(new StringContent("tom@outerspace.com"), "email");
form.Add(new StringContent("confirm whether received"), "description");
// 添加缺失的name参数
form.Add(new StringContent("Name"), "name");
form.Add(new StringContent("2"), "status");
form.Add(new StringContent("1"), "priority");

HttpResponseMessage response = await httpClient.PostAsync(_freshdeskUrl, form);

// 可以取消注释来验证响应状态
// response.EnsureSuccessStatusCode();
httpClient.Dispose();

额外优化建议：

• 不要每次创建HttpClient都Dispose，推荐复用单例HttpClient以避免socket资源耗尽
• 可以读取响应内容确认工单参数是否正确：var responseContent = await response.Content.ReadAsStringAsync();

内容的提问来源于stack exchange，提问作者Jefferson