AttributeController.cs

using System;
using System.ComponentModel.DataAnnotations;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.ModelBinding;

[RequireHttps]
[ApiController]
[Route("attributes")]
public class AttributeController
{
    [ActionContext]
    public ActionContext ActionContext { get; set; }

    [HttpGet("/are/awesome/{id}")]
    [Produces("application/json"), Consumes("application/json")]
    [ProducesResponseType(typeof(AttributeModel), StatusCodes.Status200OK)]
    public IActionResult ICanHasAttributes([FromRoute] Guid id, [FromBody, BindRequired] AttributeModel model)
    {
        if (!ActionContext.ModelState.IsValid)
        {
            return new BadRequestObjectResult(ActionContext.ModelState);
        }

        return new OkObjectResult(model);

    }

    public class AttributeModel
    {
        [Required]
        [StringLength(20)]
        public string Message { get; set; }
    }
}