Model binding not working in aspnet core web api

Question

I am working on ASP.NET Core 2.1 Web API project. I am trying to follow this article: https://www.c-sharpcorner.com/article/jwt-json-web-token-authentication-in-asp-net-core/ but I am stuck at Action. My model class just won't bind to the input.

[AllowAnonymous]
[HttpPost]
public IActionResult Login([FromBody] LoginVM loginVM)
{
    IActionResult response = Unauthorized(); // cant reach this point, my breakpoint is here
    var user = AuthenticateUser(new UserModel { });

    if (user != null)
    {
        var tokenString = GenerateJSONWebToken(user);
        response = Ok(new { token = tokenString });
    }

    return response;
}

public class LoginVM
{
    public string Username { get; set; }
    public string Password { get; set; }
}

So what is inside // some code? Are you sure it's not that giving you the error? — DavidG
– DavidG, Commented Jul 23, 2019 at 15:20
@DavidG I am unable to reach the breakpoint which is at first line in the method. — Waleed
– Waleed, Commented Jul 23, 2019 at 15:20
Can you add your main class declaration too? i'm assuming you've copied the [Route("api/[controller]")] and the [ApiController] too — Sasha
– Sasha, Commented Jul 23, 2019 at 15:27
@Sasha yes I did that but I have checked by placing break point in the constructor of the class, that point is reachable so I think routing is fine here. — Waleed
– Waleed, Commented Jul 23, 2019 at 15:28

Chris Pratt · Accepted Answer · 2019-07-23 17:47:15Z

3

You're posting as x-www-form-urlencoded, but you have the [FromBody] attribute applied to the action param. These two things are fundamentally incompatible. To accept x-www-form-urlencoded (or multipart/form-data) you must apply the [FromForm] attribute to the param. If you have [FromBody], as you do now, then you can only accept something like application/json or application/xml (if you also enable the XML serializers).

If the issue is that you want to be able to accept both application/json and x-www-form-urlencoded request bodies, that is not possible. You'll need a separate action for each request body encoding, though you can factor out the actual meat of the action into a private method on the controller that both actions can utilize.

answered Jul 23, 2019 at 17:47

Chris Pratt

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Kalimula F · Accepted Answer · 2019-07-23 15:53:46Z

0

Choose "raw" in Body and "Content-Type" as "application/json" in postman and then try.

answered Jul 23, 2019 at 15:53

Kalimula F

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