Simple POST with Web Api .NET Core

Question

I can't produce my code despite the different questions and answers found on stackoverflow.

Here is my problem, I want to receive the Username and Password of the client to perform the verification (the equality is only for the example).

However the LoginPost variable is all the time null. Furthermore I have difficulty understanding the best way to send the client an http code and json at the same time.

using Microsoft.AspNetCore.Mvc;
using web.Models;

namespace web.Controllers
{
    [Produces("application/json")]
    [Route("api/[controller]")]
    public class LoginController : ControllerBase
    {
        [HttpPost]
        public ActionResult<LoginPost> LoginPost([FromBody] LoginPost loginPost)
        {
            // (1) FAIL, loginPost variable is null

            if (loginPost.Username == loginPost.Password)
            {
                return loginPost;
            }


            // (2) How to add a message like "User/Password fails"

            return Unauthorized(); 
        }

    }
}

Note the annotations (1) and (2) in the code.

Here's the jQuery code

$.ajax({
        url: '../api/Login',
        type: 'POST',
        dataType: "json",
        contentType: "application/json, charset=utf-8",
        data: {
            Username: username,
            Password: password
        },
        statusCode: {
            200: function (data) {
                console.log(data);
            }
            401: function (data) {
                console.log(data);
            }
            500: function (data) {
                console.log(data);
            }
        }
});

and LoginPost.cs class:

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

So what does the above code do? Is there an error? If so, what is it? — DavidG
– DavidG, Commented Oct 20, 2018 at 11:12
@DavidG I explained it, I don't understand the interest of your message — Rod
– Rod, Commented Oct 20, 2018 at 11:15
@DavidG I may repeat myself but the [FromBody] LoginPost data is all the time null. I can't receive data by POST — Rod
– Rod, Commented Oct 20, 2018 at 12:05

Mike · Accepted Answer · 2018-10-20 14:56:33Z

3

Since you don't seem to want to use json, post the data as a form.

Remove contentType: "application/json, charset=utf-8", from your ajax call.

'application/x-www-form-urlencoded; charset=UTF-8' is the default so the data will be sent as a form. Also remove [FromBody] Attribute and it should work

edited Oct 20, 2018 at 14:56

answered Oct 20, 2018 at 14:11

Mike

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Comments

Marius · Accepted Answer · 2018-10-20 13:23:34Z

1

The login controller is working fine, I tested it with Postman. The problem lies with the ajax call: it does not send the data as the body of the POST request but as URL query parameters (i.e. Username=username&Password=password).

To send the data in the body of the POST request you need to send the data as json string:

data: JSON.stringify({
    "Username": "username",
    "Password": "password"
}),

answered Oct 20, 2018 at 13:23

Marius

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2 Comments

Rod Over a year ago

Well! But how to avoid the JSON.stringify function? I need to change [FromBody] to another ? With the old .NET version, it use [FromUri] but it doesn't exist here

Marius Over a year ago

The simplest solution would be to remove the [FromBody] attribute and remove contentType from the ajax call. Then the data will be sent as form data and it just works.

Amin Mozhgani · Accepted Answer · 2018-10-20 11:42:59Z

1

For (2) question, you can return status code :

return StatusCode(401, "User/Password fails");

answered Oct 20, 2018 at 11:42

Amin Mozhgani

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