ASP.NET Core无法从主体获取对象

Question

Code:

[HttpPost("user/register")]
public IActionResult Register([FromBody] User user)
{
    if (user?.Name is null || user?.Password is null)
    {
        return BadRequest(new {message = "User is null and/or name and password are not provided"});
    }
    else
    {
         // Add to db
         return Json(user);
    }
}

Also the User class:

public class User
{
    public Guid Id { get; set; }
    public string Name { get; set; }
    public string Password { get; set; }
    public string Role { get; set; }
}

---

It should basically get a user and add it to the database. I tried sending this json:

 { "Name": "Batman", "Password": "IronmanSucks"} 

The app caught the request, but the user object was null. I also tried with:

 { "user": { "Name": "Batman", "Password": "IronmanSucks"} } 

But according to this documentation , the first json should have worked fine.

Here is a link to an example http request in postman

---

Does this have to do with the headers or is it a bug in .NET Core 2.0?

Answer 1

只有在类型没有无参数构造函数的情况下才会发生这种情况，因此可以通过添加此类简单地解决。

Answer 2

I believe that the Model is coming up as invalid hence why it is null. You should try adding a [BindNever] attribute into the User class for the Role and Guid properties, seeing as you aren't using them.

If that doesn't work you may try using extended classes like so:

public class User
{
    public string Name { get; set; }
    public string Password { get; set; }
}

public class DataUser : User
{
    public Guid Id { get; set }
    public string Role { get; set; }
}

Answer 3

If you're using MVC Core instead of MVC , make sure you add Json Formaters (from Microsoft.AspNetCore.Mvc.Formatters.Json ). In your Startup.cs :

public void ConfigureServices(IServiceCollection services)
{
    services
        .AddMvcCore()
        .AddJsonFormatters();
}

This should help the [FromBody] to de-serialize your Post content