How to display a simple list from Controller to view in select element on View?

Question

Whenever I try the following code, my application seems to work correctly:

View: Index.cshtml

@{
    List<SelectListItem> listItems = new List<SelectListItem>();
    listItems.Add(new SelectListItem
    {
        Text = "Exemplo1",
        Value = "Exemplo1"
    });
    listItems.Add(new SelectListItem
    {
        Text = "Exemplo2",
        Value = "Exemplo2",
        Selected = true
    });
    listItems.Add(new SelectListItem
    {
        Text = "Exemplo3",
        Value = "Exemplo3"
    });
}

@Html.DropDownList("name", listItems)

But I do not want any logic for a list like this to happen in the View. Instead I would like the Controller to take care of this:

Controller: SelectionController.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;

namespace ExampleMVC.Controllers
{
    public class SelectionController : Controller
    {
        // GET: Selection
        public ActionResult Index()
        {
            //For first dropdown:
            List<SelectListItem> optionList1 = new List<SelectListItem>();
            optionList1.Add(new SelectListItem
            {
                Text = "Option 1",
                Value = "Option 1"
            });
            optionList1.Add(new SelectListItem
            {
                Text = "Option 2",
                Value = "Option 2"
            });
            optionList1.Add(new SelectListItem
            {
                Text = "Option 3",
                Value = "Option 3"
            });

            //For second dropdown:
            List<SelectListItem> optionList2 = new List<SelectListItem>();
            optionList1.Add(new SelectListItem
            {
                Text = "Option 1",
                Value = "Option 1"
            });
            optionList1.Add(new SelectListItem
            {
                Text = "Option 2",
                Value = "Option 2"
            });
            optionList1.Add(new SelectListItem
            {
                Text = "Option 3",
                Value = "Option 3"
            });


            List<SelectList> optionList3 = new List<SelectList>();
            optionList1.Add(new SelectListItem
            {
                Text = "Option 4",
                Value = "Option 4"
            });
            optionList1.Add(new SelectListItem
            {
                Text = "Option 5",
                Value = "Option 5"
            });
            optionList1.Add(new SelectListItem
            {
                Text = "Option 6",
                Value = "Option 6"
            });

            List<SelectListItem> listItems = new List<SelectListItem>();
            listItems.Add(new SelectListItem
            {
                Text = "Exemplo1",
                Value = "Exemplo1"
            });
            listItems.Add(new SelectListItem
            {
                Text = "Exemplo2",
                Value = "Exemplo2",
                Selected = true
            });
            listItems.Add(new SelectListItem
            {
                Text = "Exemplo3",
                Value = "Exemplo3"
            });
            ViewBag.listItems = listItems;

            ViewBag.optionList1 = optionList1;
            ViewBag.optionList2 = optionList2;
            ViewBag.optionList3 = optionList3;
            return View();
        }
    }
}

Whenever I try to call the ViewBag.listItems in my View, for example:

@Html.DropDownList("name", ViewBag.listItems)

This will return an error:

'HtmlHelper' has no applicable method named 'DropDownList' but appears to have an extension method by that name. Extension methods cannot be dynamically dispatched. Consider casting the dynamic arguments or calling the extension method without the extension method syntax.

How do I approach this problem?

Edit:

Using: @Html.DropDownList("name", (SelectList) ViewBag.listItems)

Will result in:

Microsoft.CSharp.RuntimeBinder.RuntimeBinderException: Cannot convert type of System.Collections.Generic.List to System.Web.Mvc.SelectList

@TetsuyaYamamoto I was asking for a simple example of passing list from Controller to View (not using any weird queries, database or model stuff which might scare reader concerning the subject). Title is more clear whenever someone with a similar question might be looking for this problem. Also not necessarily MVC3 related. — Barrosy, Oct 19 '18 at 09:12
@Barrosy Your question and the referenced issue is essentially same, because both implies you should not use `ViewBag` directly inside `DropDownList` helper. Instead, you need to cast into either `SelectList` or `IEnumerable` type. — Tetsuya Yamamoto, Oct 19 '18 at 09:17

score 1 · Accepted Answer · answered Oct 19 '18 at 08:59

1

You can pass your ViewBag.Item to your drop down list.

@Html.DropDownList("name", new SelectList(ViewBag.listItems, "Value", "Text"))

OR

@Html.DropDownList("name", (IEnumerable<SelectListItem>)ViewBag.listItems)

answered Oct 19 '18 at 08:59

jegtugado

5,081
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1

However, I would suggest creating a view model and pass it to your view and avoid the user of `ViewBag` as much as possible since maintaining dynamic variables is troublesome. – jegtugado Oct 19 '18 at 09:04
Apparently with the first option, the `bool Disabled` property of the SelectListItem class does not seem to work correctly and from what I have been reading is that one must point out that one is refering to an IEnumerable of type SelectListItem when trying to use this. – Barrosy Oct 19 '18 at 09:46

How to display a simple list from Controller to view in select element on View?

1 Answers1