【问题标题】：post multipart/form-data in c# HttpClient 4.5在 c# HttpClient 4.5 中发布 multipart/form-data
【发布时间】：2018-03-12 06:36:55
【问题描述】：

问题

我正在尝试发布 API 以将数据发送到 API，该 API 调用我的内部 API 服务将该数据发送到其他 API i 服务。实体包含带有文件的属性。这仅将文件发送到另一个派生，但 NameSender 属性不与文件一起发送。

实体

public class Email
{

    public string NameSender{ get; set; }

    public List<IFormFile> Files { get; set; }


}

API

[Consumes("multipart/form-data")]
[HttpPost]
public IActionResult SendEmail([FromForm]Entity entity)
{
    try
    {
        string Servicesfuri = this.serviceContext.CodePackageActivationContext.ApplicationName + "/" + this.configSettings.SendNotificationServiceName;

        string proxyUrl = $"http://localhost:{this.configSettings.ReverseProxyPort}/{Servicesfuri.Replace("fabric:/", "")}/api/values/Send";

        //attachments
        var requestContent = new MultipartFormDataContent();


        foreach (var item in entity.Files)
        {
            StreamContent streamContent = new StreamContent(item.OpenReadStream());
            var fileContent = new ByteArrayContent(streamContent.ReadAsByteArrayAsync().Result);
            requestContent.Add(fileContent, item.Name, item.FileName);

        }

        HttpResponseMessage response = this.httpClient.PostAsync(proxyUrl, requestContent).Result;


        if (response.StatusCode != System.Net.HttpStatusCode.OK)
        {
            return this.StatusCode((int)response.StatusCode);
        }

        return this.Ok(response.Content.ReadAsStringAsync().Result);
    }
    catch (Exception e)
    {
        throw e;
    }
}

【问题讨论】：

标签： c# asp.net-core-2.0 asp.net-core-webapi

【解决方案1】：

这种方法对我有用。您可以使用表单数据和文件

public async Task<bool> Upload(FileUploadRequest model)
{
    var httpClientHandler = new HttpClientHandler()
    {
      Proxy = new WebProxy("proxyAddress", "proxyPort")
      {
        Credentials = CredentialCache.DefaultCredentials
      },
      PreAuthenticate = true,
      UseDefaultCredentials = true
    };


    var fileContent = new StreamContent(model.File.OpenReadStream())
    {
       Headers =
       {
           ContentLength = model.File.Length,
           ContentType = new MediaTypeHeaderValue(model.File.ContentType)
       }
    };

    var formDataContent = new MultipartFormDataContent();
    formDataContent.Add(fileContent, "File", model.File.FileName);          // file
    formDataContent.Add(new StringContent("Test Full Name"), "FullName");   // form input

    using (var client = new HttpClient(handler: httpClientHandler, disposeHandler: true))
    {
        client.DefaultRequestHeaders.Add("Authorization", "Bearer " + tokenString);

        using (var res = await client.PostAsync("http://filestorageurl", formDataContent))
        {
           return res.IsSuccessStatusCode;
        }
    }
}

【讨论】：