Pass (Send) multiple CheckBox values with Model from View to Controller in ASP.Net Core MVC

Hello

I am using one of your checkbox examples ASP.Net Core Razor Pages: CheckBoxes (CheckBoxList) example as a base for my learning.

Now, I have a problem. I don't how to manipulate the HTTPPOST area. Your example has only one list, for me I have a whole model with multiple elements.

My ViewBag is returning a NULL, there is nothing once after I press the submit message.

my sample project has the below.

Controller:

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Rendering;
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Threading.Tasks;
using CheckBoxList_MVC_Core.Models;


namespace CheckBoxList_MVC_Core.Controllers
{
    public class OrgController : Controller
    {
        // GET: OrgController
        public ActionResult Index()
        {
            Registration NewRegistration = new Registration();
            NewRegistration.OrgList = PopulateOrgs();
            return View(NewRegistration);
        }

        [HttpPost]
        public ActionResult Index(Registration registration)
        {
            ViewBag.Message = "Selected Items:\\n";
            string Label1 = string.Empty;

            foreach (SelectListItem li in registration.OrgList)
            {
                if (li.Selected == true)
                {
                    ViewBag.Message += string.Format("{0}", li.Value);
                }
            }

            return View(registration);
        }
        public static List<SelectListItem> PopulateOrgs()
        {
            string constr = @"Data Source=.;Initial Catalog=RAJESH;Integrated Security=true";
            List<SelectListItem> items = new List<SelectListItem>();
            using (SqlConnection con = new SqlConnection(constr))
            {
                string query = " SELECT Organization_Name, Organization_Code FROM Organizations";
                using (SqlCommand cmd = new SqlCommand(query))
                {
                    cmd.Connection = con;
                    con.Open();
                    using (SqlDataReader sdr = cmd.ExecuteReader())
                    {
                        while (sdr.Read())
                        {
                            items.Add(new SelectListItem
                            {
                                Text = sdr["Organization_Name"].ToString(),
                                Value = sdr["Organization_Code"].ToString()
                            });
                        }
                    }
                    con.Close();
                }
            }
            return items;
        }
    }
}

Model:

using Microsoft.AspNetCore.Mvc.Rendering;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace CheckBoxList_MVC_Core.Models
{
    public class Registration
    {
        public string CustomerCode { get; set; }
        public string CustomerName { get; set; }
        public List<SelectListItem> OrgList { get; set; }
    }
}

and finally the view as:

@model CheckBoxList_MVC_Core.Models.Registration

<h4>Registration</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Index">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="CustomerCode" class="control-label"></label>
                <input asp-for="CustomerCode" class="form-control" />
                <span asp-validation-for="CustomerCode" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="CustomerName" class="control-label"></label>
                <input asp-for="CustomerName" class="form-control" />
                <span asp-validation-for="CustomerName" class="text-danger"></span>
            </div>
            <div>
                <table>
                    @{ List<SelectListItem> OrgListing = Model.OrgList; }

                    @foreach (var Org in OrgListing)
                    {
                        <tr>
                            <td>
                                <input id="@Org.Value" type="checkbox" name="Fruit" value="@Org.Value" checked="@Org.Selected" />
                            </td>
                            <td>
                                <label for="@Org.Value">@Org.Text</label>
                            </td>
                        </tr>
                    }
                </table>
            </div>

            <div class="form-group">
                <input type="submit" value="Submit" class="btn btn-default" />
            </div>
        </form>
    </div>
</div>


@if (ViewBag.Message != null)
{
    <script type="text/javascript">
            window.onload = function () {
                alert("@ViewBag.Message");
            };
    </script>
}

Please help