.Net core 3.0 API doesn't bind properties with hyphen

Question

Reviewed the question as it was not received well the last time. Hope I have provided all the required information below.

I have a basic API controller and my Json object doesn't seem to bind to the model properly. The root object binds but the property with hyphen in its name doesn't bind. Unfortunately, I cannot drop the hyphen in the property name.

How do I get the property to bind correctly?

using Microsoft.AspNetCore.Mvc;
using Newtonsoft.Json;

namespace TestCoreAPI.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class TestController : ControllerBase
    {
        // POST: api/Test
        [HttpPost]
        public string Post([FromBody] TestPayload testPayload)
        {
            if (testPayload == null)
            {
                return "Test payload is empty";
            }

            if (string.IsNullOrWhiteSpace(testPayload.TestProperty))
            {
                return "Test property is empty";
            }

            return "Valid input - " + testPayload.TestProperty;
        }
    }

    [JsonObject("test-payload")]
    public class TestPayload
    {
        [JsonProperty(PropertyName = "test-property")]
        public string TestProperty { get; set; }
    }
}

This is the call I'm making to the API

POST /api/test HTTP/1.1
Content-Type: application/json

{"test-property":"some string value"}

Answer 1

Net Core 3.1 does bind hyphens. Either way, the two options are Newtonsoft.Json or new-in-core-3 System.Text.Json , and they use slightly different Attribute names:

public class PostModel
{
    //This one if you are using Newtonsoft.Json
    //The Nuget dependency is Microsoft.AspNetCore.Mvc.NewtonsoftJson
    [JsonProperty(PropertyName = "kebab-case-json-field")]

    //This one of you are using the new System.Text.Json.Serialization
    [JsonPropertyName("kebab-case-json-field")]

    public string kebabCaseProperty { get; set; }
}

Meanwhile, in your Startup.cs , to use Newtonsoft, you need AddMvc() , whereas for new System.Text.Json, you don't. These both worked for me:

public void ConfigureServices(IServiceCollection services)
{
    //if using NewtonSoft
    services.AddMvc().AddNewtonsoftJson();

    //if using System.Text.Json.
    //This is the code that core 3 `dotnet new webapi` generates
    services.AddControllers();
}

Answer 2

Are you adding AddNewtonsoftJson() to your services in Startup.ConfigureServices ? If not, the new System.Text.Json is being used, not Newtonsoft. I think you'll need to do AddNewtonSoftJson() as i'm fairly sure System.Text.Json doesn't support 'kebab case' bindings.

https://docs.microsoft.com/en-us/aspnet/core/migration/22-to-30?view=aspnetcore-3.1&tabs=visual-studio#newtonsoftjson-jsonnet-support