AJAX POST giving 404 or 415 in .NETCore 2.1 with referenced Razor Class Library

Question

I have a .NETCore 2.1 web application and a separate Razor Class library.

The RCL contains some common partial views and functions which I intend to use in separate projects.

I am trying to make an AJAX post to a controller which looks like this:

using Microsoft.AspNetCore.Mvc;

namespace ThinkkaGlobal
{
    [ApiController]
    public class LoginController : Controller
    {
        [HttpPost("thinkka/login")]
        public ActionResult DoLogin([FromBody] ThinkkaUsers.Requests.LoginRequest Req)
        {
            return PartialView("Login", Req);
        }
    }
}

Note the Attribute Routing... this is not necessarily what I want, but I have spent hours now trying to get this to work that I have tried many, many different routing options. I have also got app.UseMvcWithDefaultRoute(); in my Startup.cs file.

Ultimately, what I want is an AJAX post which will return a partial view... and I would like to do this using jquery-unobtrusive-ajax, and that is how I started, but then I started using jQuery AJAX directly so I could mess about with it a bit more.

So, very basic AJAX...

$.ajax({
    url: "thinkka/login",
    type: 'post',
    contentType: "application/json", // (application/x-www-form-urlencoded; charset=UTF-8)
    dataType: 'json',
    success: function (data) {
        console.log(data);
    },
    data: { email: "[email protected]" }
});

Just a quick note, the POSTed Object is a simple Object as follows:

class LoginRequest 
{
    public string email { get; set; }
    public string password { get; set; }
    public bool remember { get; set; }
    public int location { get; set; }
    public string userpass { get; set; }
}

When I POST using contentType application/x-www-form-urlencoded; charset=UTF-8 I get Error 415 - Unsupported Media Type

When I POST using contentType application.json I get Error 404 - Not Found

For hours I was just getting 404, but I think I was genuinely using the wrong routing then. I was using thinkka/login/DoLogin as the URL, ie, including the called method name, but the routing attribute overrides this, so in all that time I wasted trying to get that to work, I think I was just using the wrong URL!

However... now... the fact that I can at least get a different error code does suggest the URL is correct?

But I don't know why I still get 404 which I used application/json, although in fact, application/x-www-form-urlencoded; charset=UTF-8 would be the correct contentType.... wouldn't it....

I don't know... it's late, I've been doing this for hours and it makes no sense anymore!

As always any help would be very much appreciated!

Answer 1

Well... I solved the problem in two stages...

Firstly to correctly return a Partial which is what I ultimately want, I changed the Controller class as follows

using Microsoft.AspNetCore.Mvc;

namespace ThinkkaGlobal
{
    [ApiController]
    public class LoginController : Controller
     {
         [Route("thinkka/login")]
         [HttpPost] 
         public PartialViewResult DoLogin([FromBody()] ThinkkaUsers.Requests.LoginRequest Req)
          {
             return PartialView("Login", Req);
         }
     }
 }

Secondly I changed the AJAX to:

$.ajax({
    url: "thinkka/login",
    type: 'post',
    contentType: "application/json",
    dataType: 'json',
    success: function (data) {
        alert('Success ' + data);
    },
    data: JSON.stringify({ email: "Email Address" })
});

Without Stringify-ing the JSON I had a 400 error on my updated Controller.

No changes to startup.cs which still contains no explicit route declarations except for app.UseMvcWithDefaultRoute(); - as mentioned previously, ,the attribute routing is needed here.

Using application/x-www-form-urlencoded; charset=UTF-8 in my AJAX I get 415 which now makes sense.

So I still don't understand

• Why do I have to stringify my JSON Post Data - or more specifically what changes do I need to make so that I don't need to...

• Why was I getting 404 with my previous Controller, which was the same in every regard except that it was declaring a ActionResult type... which in fact, for my purposes was wrong anyway, but for learning purposes.... why?