MVC下拉列表无法将所选值绑定到下拉列表

Question

在MVC项目中，我试图在下拉列表中绑定选定的值。 例如，对于AUTHOR_ID字段，文本字段将使用值和下拉列表进行归档，但所选值不会设置。

我正在使用以下类（模型）。

ProfileCard

Public Class ProfileCard
    Public Property SearchIndex As Integer
    <Key()>
    Public Property DOCNUM As String
    Public Property DOCNAME As String
    Public Property TYPIST_ID As String
    Public Property AUTHOR_ID As String
    Public Property TYPE_ID As String
    Public Property LAST_EDIT_ID As String
    Public Property APP_ID As String
    Public Property CREATION_DATE As String
    Public Property LASTEDITDATE As String
    Public Property ABSTRACT As String
    Public Property postedfile As HttpPostedFileBase
    Public Property profileError As String
    'listbox items
    Public Property GetAuthors As IEnumerable(Of SelectListItem)
    Public Property GetApplications As IEnumerable(Of SelectListItem)
    'list with profile defaults 
    Public Property ListofProfileDefaults As List(Of ProfileDefaults)
End Class

Public Class ProfileDBContext
    Inherits DbContext
    Public Property ProfileCards() As DbSet(Of ProfileCard)
End Class
Public Class ProfileDefaults

    Public Property id As String
    Public Property desc As String
    Public Property type As String

End Class

这是控制器中的编辑功能

编辑功能

Function Edit(ByVal id As Integer) As ActionResult

    Dim ds As New ProfileCard

    Dim selectpeople = (From t In db.PEOPLE
    Select New SelectListItem With {.Text = t.USER_ID.ToString, .Value = t.USER_ID.ToString})

    Dim selectapplications = (From t In db.APPS
    Select New SelectListItem With {.Text = t.APPLICATION.ToString, .Value = t.APPLICATION.ToString})

    ds.GetAuthors = selectpeople
    ds.GetApplications = selectapplications

    'list profile defaults!
    ds.ListofProfileDefaults = Session("_lProfileDefaults")

    For Each p As System.Reflection.PropertyInfo In ds.GetType().GetProperties()
        If p.CanRead Then
            If Not UCase((";SearchIndex;postedfile;GetAuthors;GetApplications;ListofProfileDefaults;")).Contains(";" & UCase(p.Name) & ";") Then
                Dim retval As Type = p.PropertyType
                Dim answer As Type = Nullable.GetUnderlyingType(retval)
                Dim value As Object
                If answer Is Nothing Then
                    value = System.Convert.ChangeType("Some value", retval)
                Else
                    value = System.Convert.ChangeType("Some value", answer)
                End If

                p.SetValue(ds, value, Nothing)
            End If
        End If
    Next

    Return View(New List(Of ProfileCard)() From {ds})

End Function

这是视图中的代码。

查看

@ModelTYPE IEnumerable(Of DMMvcApplication.ProfileCard)
@Using Html.BeginForm()
@Html.ValidationSummary(True)
@<fieldset>

     @For Each item In Model
             Dim listofrProfileDefaults = item.ListofProfileDefaults

             @For Each a In listofrProfileDefaults

                    Select Case UCase(a.id)
                        Case "DOCNUM"
                        @Html.HiddenFor(Function(modelItem) item.DOCNUM)
                    Case "DOCNAME"
                        @Html.Label(a.desc)
                        @Html.EditorFor(Function(modelitem) item.DOCNAME)

                    Case "AUTHOR_ID"
                        @Html.Label(a.desc)
                        @Html.EditorFor(Function(modelitem) item.AUTHOR_ID)
                        @Html.DropDownListFor(Function(modelitem) item.AUTHOR_ID, item.GetAuthors, New With {.class = "chosenDropDown"})

                    Case "CREATION_DATE"
                        @Html.Label(a.desc)
                        @Html.TextBoxFor(Function(modelitem) item.CREATION_DATE, "{0:d MMM yyyy}", New With {.class = "datecss"})

                    Case "APP_ID"
                        @Html.Label(a.desc)
                        @Html.DropDownListFor(Function(modelitem) item.APP_ID, item.GetApplications, New With {.class = "chosenDropDown"})

                    End Select

            Next

        @<p> 

        </p>

     Next

<p>
    <input type="submit" value="Αλλαγή" />
</p>
</fieldset>
@<div id="dialog_lookup" style="display: none">
</div>
End Using
<div>
@Html.ActionLink("Επιστροφή", "Index", "SearchResults")
</div>

谢谢， Thanasis。

更新

我想我解决了这个问题：

我有：

@Html.DropDownListFor(Function(modelitem) item.AUTHOR_ID, item.GetAuthors, New With {.class = "chosenDropDown"})

我把它改成了这个：

@Html.DropDownListFor(Function(modelitem) item.AUTHOR_ID, New SelectList(item.GetAuthors, "Value", "Text", item.AUTHOR_ID), New With {.class = "chosenDropDown"})

关键是具有Value和Text属性的新SelectList。