停止單選按鈕更改

Question

我有調用功能的單選按鈕列表。

如果該函數返回true，那麼我想更改該值。

但是，如果該函數返回false，那麼我不想更改該值並保留原始選擇值。

目前它即使在語句返回false時也會更改該值。

有什麼建議嗎？

ASP頁

<asp:RadioButtonList ID="rblType" runat="server" AutoPostBack="True" 
    DataSourceID="SqlData" DataTextField="Type" 
    DataValueField="TypeID"> 
</asp:RadioButtonList> 

VB文件

Private selectionvalue As Integer 

Protected Sub rblType_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles rblType.SelectedIndexChanged 

    Dim CheckListValidation As Boolean = CheckListBox() 

    If CheckListValidation = True Then 
      selectionvalue = rblType.SelectedItem.Value 
     Else 
      rblType.SelectedItem.Value = selectionvalue 
    End If 

End Sub 

Function CheckListBox() As Boolean 

    If lstbox.Items.Count <> "0" Then 
     If MsgBox("Are you sure you want to change option?", MsgBoxStyle.YesNo, " Change Type") = MsgBoxResult.Yes Then 
      Return True 
     Else 
      Return False 
     End If 
    Else 
     Return True 
    End If 

End Function 

Answer 1

的問題是在執行rblType_SelectedIndexChanged，所選擇的項目已經改變，RadioButtonList不 「記住」先前選定的值。您需要在回發之間保留之前選定的值以實現此目的。

我會建議使用ViewState。創建代碼隱藏的屬性來表示的ViewState值：

Private Property PreviousSelectedValue() As String 
    Get 
     If (ViewState("PreviousSelectedValue") Is Nothing) Then 
      Return String.Empty 
     Else 
      Return ViewState("PreviousSelectedValue").ToString() 
     End If 
    End Get 
    Set(ByVal value As String) 
     ViewState("PreviousSelectedValue") = value 
    End Set 
End Property 

和rblType_SelectedIndexChanged：

Protected Sub rblType_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles rblType.SelectedIndexChanged 

    Dim CheckListValidation As Boolean = CheckListBox() 

    If CheckListValidation = True Then 
     'save the currently selected value to ViewState 
     Me.PreviousSelectedValue = rblType.SelectedValue 
    Else 
     'get the previously selected value from ViewState 
     'and change the selected radio button back to the previously selected value 
     If (Me.PreviousSelectedValue = String.Empty) Then 
      rblType.ClearSelection() 
     Else 
      rblType.SelectedValue = Me.PreviousSelectedValue 
     End If 
    End If 

End Sub