How to disable content type validation for empty request bodies in ASP.NET Core 6.0

Question

Is there a way to disable the default 415 ( Unsupported Media Type ) response ASP.NET Core returns for the missing Content-Type header? Should it matter if the body is empty anyway?

[ApiController]
public class UserController : ControllerBase
{
    // This will return a 415 response if called with empty body and no `Content-Type` header.
    [HttpPost]
    [Route("/api/v2/users:search")]
    public async Task<IActionResult> SearchUsers(
        [FromBody(EmptyBodyBehavior = EmptyBodyBehavior.Allow)] SearchUsersCommand? body)
    {
        throw new NotImplementedException();
    }
}

Answer 1

Actually I didn't find the way to disable it. However, I found the solution in another question from below link :

How to disable default error response for Api Versioning

Also, to fix the error, I suggest the following solution:

For forms, use the FromForm attribute instead of the FromBody attribute.

The below controller works with ASP.NET Core 1.1:

public class MyController : Controller
{
    [HttpPost]
    public async Task<IActionResult> Submit([FromForm] MyModel model)
    {
        //...
    }
}

Answer 2

The best workaround I could find is to implement a custom MVC convention. It adds a filter to every controller to set the default content type if it's not set yet.

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc.ApplicationModels;
using Microsoft.AspNetCore.Mvc.Filters;

namespace MyWebApi
{
    internal class AllowMissingContentTypeForEmptyBodyConvention : IActionModelConvention
    {
        public void Apply(ActionModel action)
        {
            action.Filters.Add(new AllowMissingContentTypeForEmptyBodyFilter());
        }

        private class AllowMissingContentTypeForEmptyBodyFilter : IResourceFilter
        {
            public void OnResourceExecuting(ResourceExecutingContext context)
            {
                if (!context.HttpContext.Request.HasJsonContentType() && context.HttpContext.Request.ContentLength == 0)
                {
                    context.HttpContext.Request.ContentType = "application/json";
                }
            }

            public void OnResourceExecuted(ResourceExecutedContext context)
            {
                // Do nothing
            }
        }
    }
}