使用MultipartFormDataContent生成的内容类型标头错误

Question

我有以下代码：

private static string boundary = "----CustomBoundary" + DateTime.Now.Ticks.ToString("x");

private static async Task<string> PostTest()
{
    string servResp = "";

    using (var content = new MultipartFormDataContent(boundary))
    {
        content.Add(new StringContent("105212"), "case-id");
        content.Add(new StringContent("1/14/2014"), "dateFrom");
        content.Add(new StringContent("1/15/2014"), "dateTo");

        HttpClientHandler handler = new HttpClientHandler();
        cookieContainer = new CookieContainer();
        handler.CookieContainer = cookieContainer;

        HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "http://somewebsite.com/form");
        request.Headers.ExpectContinue = false;
        request.Content = content;

        httpClient = new HttpClient(handler);

        HttpResponseMessage response = await httpClient.SendAsync(request);
        response.EnsureSuccessStatusCode();

        servResp = await response.Content.ReadAsStringAsync();
    }

    return servResp;
}

当我运行它时，我看到Fiddler中的Content-Type头：

Content-Type: multipart/form-data; boundary="----CustomBoundary8d0f01e6b3b5daf"

//request.Content.Headers.Add("Content-Type", "multipart/form-data; boundary=" + boundary);
//request.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("multipart/form-data; boundary=" + boundary);

Content-Type: multipart/form-data; boundary=----CustomBoundary8d0f01e6b3b5daf

Answer 1

通过从MultipartFormDataContent中移除标头并在不进行验证的情况下将其重新添加回来，解决了这个问题：

content.Headers.Remove("Content-Type");
content.Headers.TryAddWithoutValidation("Content-Type", "multipart/form-data; boundary=" + boundary);