如何在没有ViewData的情况下绑定Html.DropDownList(强类型视图)

Question

我似乎无法找到一篇好的博客文章,其中展示了如何在没有魔术字符串"ViewData"的情况下将模型绑定到视图(使用强类型视图是我正在尝试的方法)

有没有人知道我需要在下面改变什么来直接将它绑定到我的模型？

视图

<%@ 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>

调节器

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

编辑

VB中的最终解决方案如下所示,感谢您的响应!

调节器

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

    Return View(ProductObject)
End Function

视图

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

产品类别(具有类别的IEnumeralbe属性)

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

下拉列表助手需要一个IEnumerable<SelectListItem>,而不是一个IEnumerable<Category>.通常,您所做的是让您的页面具有特定的模型.该模型包含下拉列表中所选值的属性,而不是集合.您提供的集合可通过ViewData进行选择.您可以拥有一个仅包含视图的模型,包括要从中选择的属性和集合,但这可能意味着类的扩散.关于增殖类或魔术字符串设计是否更糟,存在一些争论.

我对你的代码的看法是这样的:

<%@ 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

其中Foo是一个包含int类型属性Category的类.

如果你想做一个强类型的视图,那么让Foo有一个类型为SelectListItem的属性,然后改变:

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

至

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

和

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

至

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