C# – httpclient – how to set Content-Disposition to “application/json;” in a multipart

cdotnet-httpclientmultipartwindows-phone-8

Using System.Net.Http.Httpclient, I am trying to do a multipart post in C# and with a wp8.

This is a snippet of my code:

varclient = new HttpClient();

client.DefaultRequestHeaders.TryAddWithoutValidation(    
"Content-Type", "application/json");

content = new MultipartFormDataContent();
content.Add(new StringContent(requestObj, Encoding.UTF8, "application/json"), "request");

but using Fiddler, I noticed that I am sending this:

Content-Disposition: form-data; name=request

Content-Type: text/plain; charset=utf-8

while I need to send this (taken from an android device where the call is working):

Content-Disposition: application/json; name="request"

Content-Type: text/plain; charset=UTF-8

How to achieve the expected result?

Best Answer

What about:

setting the header on the HttpContent using TryAddWithoutValidation

and changing the MultipartFormDataContent into a MultipartContent object:

var content = new MultipartContent();

var contentData = new StringContent(requestObj, Encoding.UTF8, "application/json");
contentData.Headers.TryAddWithoutValidation("Content-Disposition", "application/json name=request");
content.Add(contentData);

This results in these headers

POST http://www.directupload.net/index.php?mode=upload HTTP/1.1
Content-Type: multipart/mixed; boundary="6905763f-e85a-44f9-b7f4-8967b357addf"
Host: www.directupload.net
Content-Length: 274
Expect: 100-continue
Connection: Keep-Alive

--6905763f-e85a-44f9-b7f4-8967b357addf
Content-Type: application/json; charset=utf-8
Content-Disposition: application/json name=request

{    "id": 1,    "name": "A green door",    "price": 12.50,    "tags": ["home", "green"]}
--6905763f-e85a-44f9-b7f4-8967b357addf--

Related Solutions

C# – HttpWebRequest, How to Send POST Data with Application/JSON Content-Type

Take a look on following example

byte[] data = CreateData(value);
var requst = (HttpWebRequest) WebRequest.Create(uri);
requst.Method = "POST";
requst.ContentType = "application/json";
requst.ContentLength = data.Length;
using (Stream stream = requst.GetRequestStream())
{
    stream.Write(data, 0, data.Length);
}

Where CreateData is

public static byte[] Create<T>(T value)
{
    var serializer = new DataContractJsonSerializer(typeof (T));
    using (var stream = new MemoryStream())
    {
        serializer.WriteObject(stream, value);
        return stream.ToArray();
    }
}

C# – How to set the Content-Type header for an HttpClient request

The content type is a header of the content, not of the request, which is why this is failing. AddWithoutValidation as suggested by Robert Levy may work, but you can also set the content type when creating the request content itself (note that the code snippet adds application/json in two places-for Accept and Content-Type headers):

HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://example.com/");
client.DefaultRequestHeaders
      .Accept
      .Add(new MediaTypeWithQualityHeaderValue("application/json"));//ACCEPT header

HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Post, "relativeAddress");
request.Content = new StringContent("{\"name\":\"John Doe\",\"age\":33}",
                                    Encoding.UTF8, 
                                    "application/json");//CONTENT-TYPE header

client.SendAsync(request)
      .ContinueWith(responseTask =>
      {
          Console.WriteLine("Response: {0}", responseTask.Result);
      });

Best Answer

Related Solutions

C# – HttpWebRequest, How to Send POST Data with Application/JSON Content-Type

C# – How to set the Content-Type header for an HttpClient request

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