Fresh ASP.NET Core API returns empty JSON objects

I have made a .NET Core Web API project to test it out.

My problem is, that the API returns an empty JSON object, when I request the endpoint, which is located at "/api/cars/123" for instance. This happens no matter what kind of object I put in, unless it's any primitive datatype, or an array thereof. The response is always:

{}


The configuration of the application is completely default, on a fresh Visual Studio 2017 installation.

I have the following classes:

**Car.cs**

namespace Ex6.Entities
{
public class Car
{
private int Id { get; set; }
private string Make { get; set; }
private string Model { get; set; }

public Car(int Id, string Make, string Model)
{
this.Id = Id;
this.Make = Make;
this.Model = Model;
}
}
}

**CarsController.cs:**

using Microsoft.AspNetCore.Mvc;
using Ex6.Entities;

namespace Ex6.Controllers
{
[Route("api/[controller]")]
public class CarsController : Controller
{

[HttpGet("{id}")]
public JsonResult GetCar(int id)
{
return Json(new Car(1, "Toyota", "Aygo" ));
}

}
}

Am I missing something?

In order for the JsonSerializer to be able to see and serialize your properties, they need to be public:

public int Id { get; private set; } //the setters can be private
public string Make { get; set; }
public string Model { get; set; }

Try this by adding configure

services.AddControllersWithViews().AddNewtonsoftJson();

....AddNewtonsoftJson() this should solve the issue.

For some reason, Text.JSON doesn't serialize public fields as well, so they need to be properties. This solved the similar issue for me