CODEWITHSUNDEEP
c#asp.net-mvcdrop-down-menu
SGekko
SGekko

Reputation: 345

Why does my DropDownList repeat same value?

I am getting values from a ViewModel into a view for form fields. In one of my DropDownList the values are correct but in another the value repeats itself instead of changing. What am I doing wrong?

ViewModel:

namespace FulfillmentPortal.ViewModels
{
public class ViewModel
{
    [Required(ErrorMessage = "Please select a carrier")]
    public List<Carrier> CarrierList { get; set; }

    [Required(ErrorMessage = "Please select a service")]
    public List<CarrierService> ServiceList { get; set; }
}
}

Controller:

public class FulfillmentController : Controller
{
    private CarrierModel db = new CarrierModel();

    // GET: Fulfillment
    public ActionResult Index()
    {
        ViewModel vm = new ViewModel
        {
            CarrierList = db.Carriers.ToList(),
            ServiceList = db.CarrierServices.ToList()
        };
        return View(vm);
    }
}

View:

@model FulfillmentPortal.ViewModels.ViewModel

@{
    ViewBag.Title = "index";
    Layout = "~/Views/Shared/_Layout.cshtml";
}
<div class="panel panel-primary">
<div class="panel-heading">REPORT OPTIONS</div>
<div class="panel-body" style="padding-left:35px;">
    <form id="processForm" class="form-horizontal" action="~/Fulfillment/Report" method="post" enctype="multipart/form-data">
        <div class="form-group">
            <label for="sel1">Carrier:</label>
            @Html.DropDownListFor(model => model.CarrierList, new SelectList(Model.CarrierList, "CarrierId", "CarrierName"), "Select a Carrier",
                new { @class = "form-control", @style = "width:auto; margin-bottom:15px;" })
            <label for="sel2">Carrier Services:</label>
            @Html.DropDownListFor(model => model.ServiceList, new SelectList(Model.ServiceList, "Code", "WebName"), "Select a Service", 
                new { @class = "form-control", @style = "width:auto; margin-bottom:15px;" })           
        </div>
    </form>
</div>
</div>

Model:

public partial class CarrierModel : DbContext
    {
        public CarrierModel()
            : base("name=CarrierModel")
        {
        }

        public virtual DbSet<Carrier> Carriers { get; set; }

        public virtual DbSet<CarrierService> CarrierServices { get; set; }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
        }
    }    

 [HttpPost]
  public ActionResult Index(ViewModel viewModel)
  {
     if (ModelState.IsValid)
     {
         viewModel.CarrierList.ToList();
         viewModel.ServiceList.ToList();
     }

       return View(viewModel);
}

This my controller now. Now my view is just erroring out. I think I am missing something or misunderstanding something.

Upvotes: 0

Views: 139

Answers (2)

TanvirArjel
TanvirArjel

Reputation: 32139

Your ViewModel should be as follows:

public class ViewModel
{
    [Required(ErrorMessage = "Please select a carrier")]
    public int CarrierId {get; set;}

    [Required(ErrorMessage = "Please select a service")]
    public int ServiceCode {get; set;}


    public List<Carrier> CarrierList { get; set; }
    public List<CarrierService> ServiceList { get; set; }
}

Then in the view:

<label for="sel1">Carrier:</label>
@Html.DropDownListFor(model => model.CarrierId, new SelectList(Model.CarrierList, "CarrierId", "CarrierName"), "Select a Carrier",
                new { @class = "form-control", @style = "width:auto; margin-bottom:15px;" })
<label for="sel2">Carrier Services:</label>
@Html.DropDownListFor(model => model.ServiceCode, new SelectList(Model.ServiceList, "Code", "WebName"), "Select a Service", 
                new { @class = "form-control", @style = "width:auto; margin-bottom:15px;" })

Then your Index Post method should be as follows:

[HttpPost]
public ActionResult Index(ViewModel viewModel)
{
    if(ModelState.IsValid)
    {
       // do whatever you want with `viewModel.CarrierId` and `viewModel.ServiceCode` here
    }

    viewModel.CarrierList = db.Carriers.ToList();
    viewModel.ServiceList = db.CarrierServices.ToList();
    return View(viewModel);
}

Upvotes: 1

Andrei
Andrei

Reputation: 56726

DropDownListFor(model => model.ServiceList

This is not how this method is supposed to work, and I suspect this is the answer to your problem.

This lambda is supposed to provide a field that will hold a value that this drop down list outputs. For your case you should have two fields in the model:

public class ViewModel
...
    public int CarrierId { get; set; }
    public string CarrierServiceCode { get; set; }

These will hold currently selected value, on none if nothing is selected (yet). And they are supposed to be used in that lambda:

DropDownListFor(model => model.CarrierServiceCode

Alternatively you could use DropDownList() method, which does not require a field in the model, and give it a custom name that will be posted with selected value.

Upvotes: 2

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