how can I get value of dropdownlist From MVC View to Controller for creating an entry in table of database?

Question

I am not sure how this works. code for View is :

@model ReservationSys.Models.Confirmed

@{
    ViewBag.Title = "Create";
}

<h2>Create</h2>


@using (Html.BeginForm()) 
{
    @Html.AntiForgeryToken()
    
<div class="form-horizontal">
    <h4>Confirmed</h4>
    <hr />
    @Html.ValidationSummary(true, "", new { @class = "text-danger" })
    <div class="form-group">
        @Html.LabelFor(model => model.RoomNumber, "RoomNumber", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownList("RoomNumber", null, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.RoomNumber, "", new { @class = "text-danger" })
        </div>
    </div>

    <div class="form-group">
        @Html.LabelFor(model => model.ReservationId, "ReservationId", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownList("ReservationId", null, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.ReservationId, "", new { @class = "text-danger" })
        </div>
    </div>
    <div class="form-group">
        @Html.LabelFor(model => model.Reservation.Customer.CustomerName, "CustomerName", htmlAttributes: new { @class = "control-label col-md-2" })
        <div class="col-md-10">
            @Html.DropDownList("CustomerName", null, htmlAttributes: new { @class = "form-control" })
            @Html.ValidationMessageFor(model => model.Reservation.Customer.CustomerName, "", new { @class = "text-danger" })
            
        </div>
    </div>




    <div class="form-group">
        <div class="col-md-offset-2 col-md-10">
            <input type="submit" value="Create" class="btn btn-default" />
        </div>
    </div>
</div>
}

<div>
    @Html.ActionLink("Back to List", "Index")
</div>

@section Scripts {
    @Scripts.Render("~/bundles/jqueryval")
}

Similarly, code in controller to create entry in database is :

  [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Create([Bind(Include = "Id,RoomNumber,ReservationId")] Confirmed confirmed)
        {

            if (ModelState.IsValid)
            {
                
                db.Confirmeds.Add(confirmed);
                db.SaveChanges();
                return RedirectToAction("Index");
            }

            ViewBag.ReservationId = new SelectList(db.Reservations, "ReservationId", "ReservationId", confirmed.ReservationId);
            ViewBag.RoomNumber = new SelectList(db.Rooms, "RoomNumber", "RoomType", confirmed.RoomNumber);
            return View(confirmed);
        }

Can someone help me here to understand, how the selected value of dropdown is passed ?

I want to find reservation Id by using Customer Name for which I have created function like :

// get customer id using customer name that comes from dropdown list
 public  Customer GetCustomerId(string name)
        {
            Customer Customer = new Customer();
            Customer=db.Customers.Find(name);

            return Customer;
        }
        // use customer Id to get Reservation ID to enter in Reservation table of database
        public Reservation getReservationId(int id)
        {
            Reservation reservation = db.Reservations.Find(id);
            return reservation;
        }

thanks in advance.

Answer 1

how the selected value of dropdown is passed ?

You can use asp-items,to new SelectList,it will show it's text and bind it's value to the property you want by ModelBinding.

Below is a work demo, you can refer to it. Custom.cs:

public class Custom
    {
        public string name{ get; set; }
        public int Id { get; set; }
       
    }

CustomViewModel.cs:

public class CustomViewModel
    {
        public string name { get; set; }
        public List<Custom> Customlist { get; set; }
    }

In HomeContoller:

 public IActionResult Index()
        {

        var Customlist = new List<Custom>()
         {
        new Custom { name = "Khushbu",Id= 1 },
        new Custom { name = "Mohan", Id = 2 },
        new Custom { name = "John", Id = 3 },
        new Custom { name = "Martin", Id= 4 },
        new Custom { name = "Due", Id= 5 }
        };

            var model = new CustomViewModel();
            model.Customlist = Customlist;
            return View(model);
        }
        [HttpPost]
        public IActionResult GetCustomerId(string name)
        {
            return View();
        }

If you are getting data from the database, then you can bind it like below,

model.Customlist= db.Select(x => new Custom { Id = x.Id, Text = x.name }).ToList();

Index view:

@model CustomViewModel

@{
    ViewData["Title"] = " List";
}

<div class="text-center">
    <h1 class="display-4">Custom Dropdown</h1>

    <form asp-action="GetCustomerId" asp-controller="home" method="post">

        <div class="row">
            <div class="col-md-4">
                <select id="drpEmpList" class="form-control" asp-for="name" asp-items="@(new SelectList(Model.Customlist, "name","name" ))">
                    <option value="">--Select--</option>
                </select>
             

            </div>
            <div class="col-md-2">
                <input type="submit" name="btnSubmit" value="Submit" class="btn btn-success" />
            </div>
        </div>

    </form>
</div>

Result: