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使用MSDN上找到的樣品說明：問題與在視圖MVC 2.0 dropdownfor元件選擇selcteditem - 始終選擇第一元件
的SelectList類（http://msdn.microsoft.com/en-us/library/system.web.mvc.selectlist_members(v=vs.90).aspx）
SelectListItem（http://msdn.microsoft.com/en-us/library/system.web.mvc.multiselectlist.items(v=vs.90).aspx）
和IEnumerable（http://msdn.microsoft.com/en-us/library/system.collections.ienumerable(v=vs.90).aspx）
我已經創建了示例Person/People代碼中的以下類。
Public Class Choice
'
Private _Value As String = Nothing
Private _Text As String = Nothing
Private _Selected As Boolean = Nothing
'
Property ItemValue As String
Get
Return _Value
End Get
Set(value As String)
_Value = value
End Set
End Property
'
Property ItemText As String
Get
Return _Text
End Get
Set(value As String)
_Text = value
End Set
End Property
'
Property ItemSelected As Boolean
Get
Return _Selected
End Get
Set(value As Boolean)
_Selected = value
End Set
End Property
'
Public Sub New(ByVal pValue As String, ByVal pText As String)
Me._Value = pValue
Me._Text = pText
Me._Selected = False
End Sub
'
Public Sub New(ByVal pValue As String, ByVal pText As String, pSelected As Boolean)
Me._Value = pValue
Me._Text = pText
Me._Selected = pSelected
End Sub
'
End Class
Public Class Choices
Implements IEnumerable
'
Private _Choices() As Choice
'
Public ReadOnly Property SelectedValue() As Choice
Get
Dim i As Integer = Nothing
Dim x As Choice = Nothing
For i = 0 To _Choices.Length - 1
If _Choices(i).ItemSelected Then
x = _Choices(i)
Exit For
End If
Next i
Return x
i = Nothing
x = Nothing
End Get
End Property
'
Public Sub New(ByVal pArray() As Choice)
_Choices = New Choice(pArray.Length - 1) {}
Dim i As Integer
For i = 0 To pArray.Length - 1
_Choices(i) = pArray(i)
Next i
End Sub
'
Public Function GetEnumerator() As IEnumerator Implements IEnumerable.GetEnumerator
Return New ChoicesEnum(_Choices)
End Function
'
End Class
Public Class ChoicesEnum
Implements IEnumerator
'
Public _Choices() As Choice
'
Dim position As Integer = -1
'
Public Sub New(ByVal list() As Choice)
_Choices = list
End Sub
'
Public Function MoveNext() As Boolean Implements IEnumerator.MoveNext
position = position + 1
Return (position < _Choices.Length)
End Function
'
Public Sub Reset() Implements IEnumerator.Reset
position = -1
End Sub
'
Public ReadOnly Property Current() As Object Implements IEnumerator.Current
Get
Try
Return _Choices(position)
Catch ex As IndexOutOfRangeException
Throw New InvalidOperationException()
End Try
End Get
End Property
'
End Class
在我的模型我有如下
Private _Gender As Integer = Nothing
在我的控制器宣佈它是我實例化一個選擇列表的如下：
Friend Function GetGenderList(SelId As Integer) As SelectList
'
Dim ChoicesArray() As Choice = { _
New Choice("0", "Please Select Gender", IIf(SelId = 0, True, False)), _
New Choice("1", "Male", IIf(SelId = 1, True, False)), _
New Choice("2", "Female", IIf(SelId = 2, True, False)), _
New Choice("3", "Unspecified", IIf(SelId = 3, True, False))}
Dim ChoicesList As New Choices(ChoicesArray)
GetGenderList = New SelectList(ChoicesList, ChoicesList(SelId))
ChoicesList = Nothing
ChoicesArray = Nothing
'
End Function
然後我通過選擇列表的的可視數據的查看
<ChildActionOnly()> _
Function EditPersonalUserCtrl(ByVal MyPersonal As MemberPersonalModel, FoundErrorInfo As String) As PartialViewResult
Dim sxGenderList As SelectList = Nothing
sxGenderList = GetGenderList(MyPersonal.Gender)
ViewData.Add("Gender", sxGenderList)
ViewData.Add("FoundErrorInfo", FoundErrorInfo)
Return PartialView(MyPersonal)
sxGenderList = Nothing
End Function
在我看來，HTML是如下
<tr>
<td class="FormFieldLabel" style="width: 30%;">Gender</td>
<td class="FormFieldLabel" style="width: 70%;">
<%= Html.DropDownListFor(Function(Model) Model.Gender, New SelectList(ViewData("Gender").Items, "ItemValue", "ItemText", "ItemSelected"), New With {.style = "font-family: Tahoma; font-size: 14pt; color: #333333;"})%>
<%= Html.ValidationMessageFor(Function(Model) Model.Gender)%>
</td>
</tr>
當我嘗試編輯/更新視圖中的SelectList /下拉始終顯示在列表中的第一個選項的項目，無論什麼或選定。
它讓我困惑了兩天，我看不到它出錯的地方！ 請有人看看我的代碼，看看它向西走哪裏。
在此先感謝。