Remove content-disposition and *filename from MultipartFormDataContent

Question

I need to create a POST request using.Net 5 in the following format:

POST
https://someLMShost.edu/d2l/api/le/{version}/{orgUnit}/content/modules/{moduleId}/structure/
HTTP/1.1
Content-Type: multipart/mixed;boundary=xxBOUNDARYxx
Content-Length: {POST body in length in bytes}

--xxBOUNDARYxx
Content-Type: application/json

{"IsHidden": false, "IsLocked": false, "ShortTitle": "Test", "Type": 1, "DueDate": null, "Url": "/content/extensibility/EXT-104/file.txt", "StartDate": null, "TopicType": 1, "EndDate": null, "Title": "Test topic content"}
--xxBOUNDARYxx
Content-Disposition: form-data; name=""; filename="file.txt"
Content-Type: text/plain

This is a sample text file
with some text content.
--xxBOUNDARYxx--

My code looks like this:

var apiResponse = new HttpResponseMessage();

var stringContent = new StringContent(content, Encoding.UTF8, "application/json");
stringContent.Headers.ContentType.CharSet = "";
var stringfile = new StringContent(file, Encoding.UTF8, "text/plain");  
stringfile.Headers.ContentType.CharSet = "";

MultipartFormDataContent form = new MultipartFormDataContent
{
    stringContent,
    { stringfile, "\"\"", "\"file.txt\"" }
};

apiResponse = await _client.PostAsync(request, form);

My code is producing the following request:

POST
https://instance.desire2learn.com/d2l/api/le/1.60/329015/content/modules/9885759/structure/?x_a=qwerty&x_b=qwerty&x_c=qwert&x_d=qwerty&x_t=qwert HTTP/1.1
Host: instance.desire2learn.com
traceparent: 00-aff8b6564150364bac900043e5f0daa7-a3512fc259a59c49-00
Content-Type: multipart/form-data; boundary="27d7ac2d-6f96-4c17-84d8-2a93da333bab"
Content-Length: 565

--27d7ac2d-6f96-4c17-84d8-2a93da333bab
Content-Type: application/json
Content-Disposition: form-data

{"Title":"Test topic content","ShortTitle":"Test","Type":1,"TopicType":1,"Url":"/content/enforced/Sandbox/testHTML.html","StartDate":null,"EndDate":null,"DueDate":null,"IsHidden":false,"IsLocked":false}

--27d7ac2d-6f96-4c17-84d8-2a93da333bab
Content-Type: text/plain
Content-Disposition: form-data; name=""; filename="file.txt" ; filename*=utf-8''%22file.txt%22

test
--27d7ac2d-6f96-4c17-84d8-2a93da333bab--

How would I go about removing the bolded parts of the request? "Content-Disposition: form-data" from the first part and "; filename*=utf-8''%22file.txt%22" from the second part.

Answer 1

Probably MultipartFormDataContent is not the right content type for this case. Try using MultipartContent like shown below.

var stringContent = new StringContent(content, Encoding.UTF8, "application/json");
stringContent.Headers.ContentType.CharSet = string.Empty;

var stringFile = new StringContent(file, Encoding.UTF8, "text/plain");
stringFile.Headers.ContentType.CharSet = string.Empty;
stringFile.Headers.ContentDisposition = new ContentDispositionHeaderValue("form-data")
{
    FileName = file,
    Name = "\"\""
};

var multiPartContent = new MultipartContent
{
    stringContent,
    stringFile
};