C# generated client using FormUrlEncodedContent instead of StringContent

I am working with an API that generate a specification like this:

{
    "swagger": "2.0",
    "info": {
        "version": "v1",
        "title": "SwaggerTest"
    },
    "host": "localhost:44386",
    "schemes": [
        "https"
    ],
    "paths": {
        "/api/Values": {
            "post": {
                "tags": [
                    "Values"
                ],
                "operationId": "Values_Post",
                "consumes": [
                    "application/json",
                    "text/json",
                    "application/xml",
                    "text/xml",
                    "application/x-www-form-urlencoded"
                ],
                "produces": [],
                "parameters": [
                    {
                        "name": "value",
                        "in": "body",
                        "required": true,
                        "schema": {
                            "type": "string"
                        }
                    }
                ],
                "responses": {
                    "204": {
                        "description": "No Content"
                    }
                }
            }
        }
    },
    "definitions": {}
}

This used to generate code like this:

var content_ = new System.Net.Http.StringContent(Newtonsoft.Json.JsonConvert.SerializeObject(value, _settings.Value));
content_.Headers.ContentType = System.Net.Http.Headers.MediaTypeHeaderValue.Parse("application/json");

Today I updated NSwagStudio and now it generates code like this:

var json_ = Newtonsoft.Json.JsonConvert.SerializeObject(value, _settings.Value);
var dictionary_ = Newtonsoft.Json.JsonConvert.DeserializeObject<System.Collections.Generic.Dictionary<string, string>>(json_, _settings.Value);
var content_ = new System.Net.Http.FormUrlEncodedContent(dictionary_);
content_.Headers.ContentType = System.Net.Http.Headers.MediaTypeHeaderValue.Parse("application/json");

This looks like an error from the API since it should only accept application/json but I do not have access to the API source code, if I manually delete the application/x-www-form-urlencoded from consumes, it works like before but I would like to understand if this change is a bug or if there is something I can configure on client-side to be able to generate the code as it was.

[vincenzolauretta]

Hi, hopefully this helps someone who has this issue on Asp.net (.NET Framework)

I added the following custom filter class:

    internal class AssignContentTypeFilter : IOperationFilter
    {
        public void Apply(Operation operation, SchemaRegistry schemaRegistry, ApiDescription apiDescription)
        {
            operation.consumes.Clear();
            operation.consumes.Add("application/json");

            operation.produces.Clear();
            operation.produces.Add("application/json");
        }
    }

then in SwaggerConfig.cs:

c.OperationFilter<AssignContentTypeFilter>();

reference link: https://stackoverflow.com/questions/58973329/asp-net-core-3-0-swashbuckle-restrict-responses-content-types-globally

[igorvorona]

Having the same issue with FormUrlEncodedContent generated instead of StringContent. It fails in controller’s endpoint unable to populate model class [FromBody]:

public async Task<IHttpActionResult> MyEndpoint([FromBody] MyModel model)

model is always null now. Why was the change, it was working fine in v13.10.8.0