How to bind Html.DropDownList without ViewData (strongly typed view)

Question

I can’t find a good blog post that shows how to bind a model to a view without the "ViewData" magic lines (using a strongly typed view is the approach I'm trying to do)

Does anyone know what I need to change below to link this directly to my model?

View

<%@ Page Language="VB" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage(Of IEnumerable (Of MvcApplication1.Category))" %>
<asp:Content ID="aboutContent" ContentPlaceHolderID="MainContent" runat="server">
    <%=Html.DropDownList("CategoryList")%>
</asp:Content>

controller

Function Index() As ActionResult
    Dim list As New List(Of Category)
    list.Add(New Category With {.CategoryID = 1, .CategoryName = "Test1"})
    list.Add(New Category With {.CategoryID = 2, .CategoryName = "Test2"})

    Return View()
End Function

EDIT

The final solution in VB is shown below, thanks for the great answer!

controller

Function Index() As ActionResult
    Dim id As Integer = 1
    Dim ProductObject As Product = mProductService.GetProductById(id)

    Return View(ProductObject)
End Function

View

<%=Html.DropDownList("Category", New SelectList(Model.Categories, "CategoryID", "CategoryName"))%>

Product class (without IEnumeralbe property for categories)

Public Class Product
    Public Sub New()

    End Sub


    Private mProductID As Integer
    Public Property ProductID() As Integer
        Get
            Return mProductID
        End Get
        Set(ByVal value As Integer)
            mProductID = value
        End Set
    End Property

    ReadOnly Property Categories() As IEnumerable(Of Category)
        Get
            Dim list As New List(Of Category)
            list.Add(New Category With {.CategoryID = 1, .CategoryName = "Test1"})
            list.Add(New Category With {.CategoryID = 2, .CategoryName = "Test2"})

            Return list
        End Get
    End Property

End Class

Answer 1

IEnumerable<SelectListItem>, IEnumerable<Category>. , , . , . ViewData. , , , . , .

:

<%@ Page Language="VB" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage(Of Foo)" %>
<asp:Content ID="aboutContent" ContentPlaceHolderID="MainContent" runat="server">
    <%=Html.DropDownList("Category", ViewData("CategoryList"))%>
</asp:Content>

Function Index() As ActionResult
    Dim list As New List(Of SelectListItem)
    list.Add(New SelectListItem  With {.Value = 1, .Text = "Test1"})
    list.Add(New SelectListItem With {.Value = 2, .Text = "Test2"})
    ViewData("CategoryList") = list
    Return View()
End Function

Foo - , Category int.

, Foo SelectListItem, :

<%=Html.DropDownList("Category", ViewData("CategoryList"))%>

<%=Html.DropDownList("Category", Foo.Categories )%>

    ViewData("CategoryList") = list
    Return View()

    Dim foo as New Foo
    foo.Categories = list
    Return View(foo)

Answer 2

Html.DropDownList, DropDownList.

, , . ViewData .

:

, "", , , , , , ( , IEnumerable). HtmlHelper.

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

namespace MvcApplication3.Helpers
{
    public static class ViewHelpers
    {
        public static string ModelDropDownList(this HtmlHelper htmlHelper, string name)
        {
            var model = htmlHelper.ViewData.Model as IEnumerable<SelectListItem>;
            if(model == null)
                return string.Empty;

            return htmlHelper.DropDownList(name, model);
        }
    }
}

<%@ Page Title="" Language="C#" MasterPageFile="~/Views/Shared/Site.Master" Inherits="System.Web.Mvc.ViewPage<IEnumerable<SelectListItem>>" %>
<asp:Content ID="Content2" ContentPlaceHolderID="MainContent" runat="server">
    <%= Html.ModelDropDownList("Test") %>
</asp:Content>

Answer 3

If you want to use the Strongly Typed method, there is a SelectList object with which you can pass IEnumerable. You must specify the properties of the text field and the values ​​of the T field, but this SelectList object can be directly allocated to the Html.DropDownList helper:

c#
IList<Category> categories = new IList<Category>()
    {
        new Category() { ID = 1, Name = "Category 1" },
        new Category { ID = 2, Name = "Category 2" }
    };

SelectList categoryDropDown = new SelectList(categories, "ID", "Name");

ViewData["categoryDropDown"] = categoryDropDown;

then do:

c#
<%=Html.DropDownList("CategoryID", ViewData("categoryDropDown"))%>

Thus, you can switch to IList categories from anywhere (Service layer, wide controller method).