In multipart form, JSON part is missing the JSON content type in the content disposition header

[kbilkhoo]

Describe the bug
Request.Form containd no data

To Reproduce

client side

    var request = new RestRequest(resource);
    var jsonData = new
    {
            Company = "Microsoft",
            ZipCode = "LS339",
            Country = "USA"

    };

    request.RequestFormat = DataFormat.Json;
    request.Method = Method.Post;
    request.AddHeader("Content-Type", "multipart/form-data");
    request.AddFile("content", file, "application/octet-stream"); 
    request.AddJsonBody(jsonData);


    var response = client.ExecuteAsync(request).Result;

server side

   var request = HttpContext.Current.Request;
   Request.Form[0]; // index out of range exception

Expected behavior

    Request.Form[0]; // expected data

Stack trace
There is not stack trace for this issue. Except behaviour has changed
after upgrading from 106.13.0 to 107.1.1

106.13.0 -> Request.Form contains key called 'application/json'
107.1.1 -> Request.Form no data

Desktop (please complete the following information):

OS: Windows 10
.NET version 4.7.2
Version: 107.1.1
Additional context

workaround

changed request.AddJsonBody(jsonData) ->request.AddParameter("application/json", JsonConvert.SerializeObject(jsonData));
has resolved the issue in 107.1.1

[kbilkhoo]

All working now, changed the line

request.AddJsonBody(dataToPost) ->  request.AddParameter("application/json", JsonConvert.SerializeObject(dataToPost));

request.Form now contain the posted json data

[alexeyzimarev]

Have you followed the bug report issue template? We ask to trace both working and non-working requests, so it's possible to see the difference.

[kbilkhoo]

Sorry I did not, but can do later on if you wish

[alexeyzimarev]

Here is what I found.

RS 106 JSON data:

Content-Type: application/json.
Content-Disposition: form-data; name="application/json".
.
{"Company":"Microsoft","ZipCode":"LS339","Country":"USA"}.

RS 107:

Content-Type: application/json; charset=utf-8.
Content-Disposition: form-data.
.
{"company":"Microsoft","zipCode":"LS339","country":"USA"}.

Apparently, the content type for the JSON form part is not set properly in the content disposition header. I'll look into it.

[alexeyzimarev]

No, I think I wrote some rubbish. The content type is correct. The only difference is that the part name is not set to "application/json", which doesn't seem to be any kind of requirement.

Nevertheless, I must've been there for a reason to use the body parameter content type as the content disposition form part name. Looks weird to me, but who knows. The 107.1.2-alpha.0.10 sets it as before, you might want to try it out.

[kbilkhoo]

Hi, Upgraded to 107.1.2-alpha.0.18 now I get a different error, when calling client.ExecuteAsync(request).Result;

Message = "The type initializer for 'RestSharp.HttpContentExtensions' threw an exception."

Message = "Instance field '_boundary' is not defined for type 'System.Net.Http.MultipartContent'"

at RestSharp.HttpContentExtensions.GetFormBoundary(MultipartFormDataContent content)
at RestSharp.RequestContent.GetContentTypeHeader(String contentType)
at RestSharp.RequestContent.g__AddHeader|15_1(Parameter parameter)
at RestSharp.Extensions.CollectionExtensions.ForEach[T](IEnumerable1 items, Action1 action)
at RestSharp.RequestContent.AddHeaders()
at RestSharp.RequestContent.BuildContent()
at RestSharp.RestClient.d__1.MoveNext()
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at RestSharp.RestClient.d__0.MoveNext()

[alexeyzimarev]

It seems to be platform-specific. I expected it, the old code is still in place. The issue is that the MultipartFormBoundary class doesn't expose the boundary property, although they have it inside. The current implementation accesses it via reflections, but I thought it might not work on some platforms.

I am considering replacing the boundary generated by the content class with another GUID that I can keep and access. It should resolve the issue.

[alexeyzimarev]

And, I think you are not on .NET 5 or 6, right?

[kbilkhoo]

correct, we are currently using .NET 4.7.2 to test the API,

[alexeyzimarev]

Ok, it's better than I thought. It's possible to provide the boundary value instead of letting the content generate it.