JSON Parameter in ASP.NET MVC using [FromBody]

To force Web API to read a simple type from the request body, add the [FromBody] attribute to the parameter:

public class Person
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
}

[Route("hello2"), HttpPost]
public JsonResult Hello2([FromBody] Person person)
{
    string output = $@"Hello {person.FirstName} {person.LastName}";
    return Json(output);
}

When a parameter has [FromBody], Web API uses the Content-Type header to select a formatter. In this example, the content type is “application/json” and the request body is a raw JSON string (not a JSON object).

References
https://docs.microsoft.com/en-us/aspnet/web-api/overview/formats-and-model-binding/parameter-binding-in-aspnet-web-api