停止单选按钮更改

Question

我有一个调用函数的单选按钮列表。

如果函数返回 true，那么我想更改值。

但是，如果函数返回 false，那么我不想更改值并保留原始选择值。

目前，即使语句返回 false，它也会更改值。

有什么建议吗？

ASP 页面

<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

问题是当rblType_SelectedIndexChanged 被执行时，选择的项目已经改变并且RadioButtonList 不“记住”之前选择的值。为了实现这一点，您需要在回发之间保留先前选择的值。

我建议使用 ViewState。在后面的代码中创建一个属性来表示 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

在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