Asp.net web API in .net core

It sounds like you're using MedioClinic as an example for your migrated Kentico Xperience 13 website? You just need to add ApiControllers to the project like this.

This is a REST WebAPI controller which is included in the demo website. You can do the same thing in your project and migrate the controllers from the Kentico 12 Portal Engine website.

Well, I think I adapted it fine, but I am still not able to access it. Is there somewhere I need to register it?

Here is the base code:

namespace QuitLogix.Controllers
{
    [ApiController]
    //[Route("api/[controller]")]
    [Route("api/ProsAndCons")]
    public class ProsAndConsController : ControllerBase
    {
        private readonly IPageBuilderDataContextRetriever _pageBuilderDataContextRetriever;
        private readonly IPageRetriever _pageRetriever;
        private readonly ISiteService _siteService;
        private readonly IFileService _fileService;
        private readonly IOptionsMonitor<XperienceOptions> _optionsMonitor;
        private readonly ProsConsDataRepository _prosConsDataRepository;


        public enum ItemType
        {
            Pro,
            Con
        }

        public class ProsAndConsModel
        {
            public List<ProsAndCons> Pros { get; set; }
            public List<ProsAndCons> Cons { get; set; }
            public HttpStatusCode StatusCode { get; set; }
        }



        public ProsAndConsController(
                 IPageBuilderDataContextRetriever pageBuilderDataContextRetriever,
                 IPageRetriever pageRetriever,
                 ISiteService siteService,
                 IFileService fileService,
                 IOptionsMonitor<XperienceOptions> optionsMonitor,
                 ProsConsDataRepository prosConsDataRepository)
        {
            _pageBuilderDataContextRetriever = pageBuilderDataContextRetriever ?? throw new ArgumentNullException(nameof(pageBuilderDataContextRetriever));
            _pageRetriever = pageRetriever ?? throw new ArgumentNullException(nameof(pageRetriever));
            _siteService = siteService ?? throw new ArgumentNullException(nameof(siteService));
            _fileService = fileService ?? throw new ArgumentNullException(nameof(fileService));
            _optionsMonitor = optionsMonitor ?? throw new ArgumentNullException(nameof(optionsMonitor));
            _prosConsDataRepository = prosConsDataRepository ?? throw new ArgumentNullException(nameof(prosConsDataRepository));
        }

        [HttpGet]
        [ValidateAntiForgeryToken]
        public async Task<ProsAndConsModel> Get(string data)
        {
            var result = new ProsAndConsModel()
            {
                Pros = new List<ProsAndCons>(),
                Cons = new List<ProsAndCons>()
            };
            try
            {...

I am just not sure where I am going wrong with this.

Well after a bit of fiddling I went smaller and am just trying a test route.

using Microsoft.AspNetCore.Mvc;
using System.Net;

namespace APIControllers
{
    [ApiController]
    public class ClassController : ControllerBase
    {

        public class testModel
        {
            public int id { get; set; }
            public string data { get; set; }
        }


        public ClassController() { }

        [HttpGet("api/class/{id}")]
        [ValidateAntiForgeryToken]
        public ActionResult<testModel> Get(int id = 0)
        {
            var model = new testModel();
            model.data = "test data";
            model.id = id;

            return Ok(model);
        }
    }
}

with this when I call it I get the response:

{"type":"https://tools.ietf.org/html/rfc7231#section-6.5.1","title":"Bad Request","status":400,"traceId":"00-5ae3d3fac567846c7931ddc8fb5b08e6-af8527bc78a0818b-00"}

Any ideas?