How to bind returned data to a Telerik ASP.Net Core grid after submitting a form with resulted data

Question

I am creating a web app using ASP.Net Core MVC 3.1 With EF 3.1. I add a web page to update student Telephone numbers as batches (Grade wise) using ASP.Net Core Telerik Grid. There is a small form at the top of the Page and there are buttons and those allow to select the Grade that you want to update Telephone numbers of students. I need to show relevant students data in ASP.Net Core Telerik Grid below the Form control after clicking on a Grade button. After Clicking on a Grade button, it selects and returned back relevant data but the grid does not show those data.

So My question is, how should I correct my coding, in order to view returned data?

My coding are as follows

Index.cshtml

@model School_MGT.Models.Students

<div class="container">
    <div class="container">
        <form asp-controller="AttendenceStudents" asp-action="Index">
            <p align="center">
                <input type="submit" name="btn" value="1A" />
                <input type="submit" value="1B" name="btn" />
            </p>
        </form>
    </div>
</div>
@(Html.Kendo().Grid<School_MGT.Models.Students>()
    .Name("Grid")
    .Columns(columns =>
        {
            columns.Bound(p => p.Add_No);
        columns.Bound(p => p.S_Name).Width(140);
        columns.Bound(p => p.Tel_H).Width(140);

    })
    .ToolBar(toolbar =>
        {
        toolbar.Create();
        toolbar.Save();
        })
    .Editable(editable => editable.Mode(GridEditMode.InCell))
    .Pageable()
    .Navigatable()
    .Sortable()
    .Scrollable()
    .Resizable(resize => resize.Columns(true))
    .DataSource(dataSource => dataSource
        .Ajax()
        .Batch(true)
        .PageSize(20)
        .ServerOperation(false)        
        .Model(model => model.Id(p => p.Add_No))
        .Update("Update", "AttendenceStudents")
    )
)

AttendenceStudentsController

namespace School_MGT.Controllers
{
    public class AttendenceStudentsController : Controller
    {
        private readonly ConnectionString _context;

        public AttendenceStudentsController(ConnectionString context)
        {
            _context = context;
        }
        public IActionResult Index()
        {
            return View();
        }
        [HttpPost]
        public  IActionResult Index(string btn)
        {
            var Students = from m in _context.Students select m;
            switch (btn)
            {
                case "1A":
                    Students = Students.Where(x => x.Grade == "1" && x.Class == "A");
                    return View();

                case "1B":
                Students = Students.Where(x => x.Grade == "1" && x.Class == "B");
                    return View();

                default:                   
                    return (View());
            }
        }

        [HttpPost]
        public IActionResult Update([Bind("RowID,Add_No,S_Name")] Students target)

        {
            Students entity = _context.Students.FirstOrDefault((r => r.Add_No == target.Add_No));            
            entity.Tel_H = target.Tel_H;           
            _context.SaveChanges();
            return View();
        }
    }
}

Answer 1

Thank you all who viewed my question and try to answer. I resolved my problem by modifying Index method and view.cshtml

 public async Task<IActionResult> Index(string btn)
        {

            var Students = from m in _context.Students select m;

            switch (btn)
            {
                case "1A":
                    Students = Students.Where(x => x.Grade == "1" && x.Class == "A");
                    return View(await Students.ToListAsync());

                case "1B":
                Students = Students.Where(x => x.Grade == "1" && x.Class == "B");
                    return View(await Students.ToListAsync());

                default:

                    return (View(await Students.ToListAsync()));
            }          

        }

apply following changes to model and grid

@model IEnumerable<School_MGT.Models.Students>

@(Html.Kendo().Grid(Model)