Question

我有一个动态列表框，我想添加一个动态验证器控件，以便用户必须从列表框中选择2个选项 - 不多也不少。我玩过rangevalidator和regularexpressionvalidator控件，但它们没有用。有没有人在那里做过这件事？

Answer 1

您必须编写自定义验证程序。

Answer 2

您必须编写自定义验证程序，然后在按钮单击事件或任何此类事件上添加类似于您的customvalidator组的验证组。

在后面的代码中，我从gridview中找到了我的复选框，并检查是否选择了更多项目。

    <asp:CustomValidator ID="customValidatorForCheckboxlist" 
        runat="server"   ErrorMessage="Required Field" ValidationGroup="valSurvey"
   OnServerValidate="CheckifCheckBoxHasMoreItems" SetFocusOnError="true" Display="Dynamic"></asp:CustomValidator>





 Protected Sub CheckifCheckBoxHasMoreItems(ByVal sender As Object, ByVal e As ServerValidateEventArgs)
            'This code block is for custom Validator known as customValidatorForCheckboxlist
            Dim count As Integer
            For Each gvrow As GridViewRow In gridview1.Rows
                'Initialize a New instance of ContextAttributeArtifacts and ContextAttributesArtifactsOpenEnded and Assign Properties to Them.
                For Each ct As Control In gvrow.Cells(1).Controls
                    If ct.GetType.ToString().Equals("System.Web.UI.WebControls.CheckBoxList") Then
                        Dim _checkboxlist As CheckBoxList = DirectCast(ct, CheckBoxList)
                        For Each ListItem1 As ListItem In _checkboxlist.Items
                            If ListItem1.Selected = True Then
                                valbool = True
                                count = count + 1
                            End If
                        Next
                    End If
                Next

            Next
            If count > 2 Then
                e.IsValid = False
            ElseIf count < 2 Then
                e.IsValid = True
            End If
        End Sub

Answer 3

自定义验证器很好......但代码非常简单：

Protected Sub myCustomVal(ByVal sender As Object, ByVal e As ServerValidateEventArgs)

   If ListBox1.GetSelectedIndices.Length =2 THEN
      e.isvalid = true
   Else
      e.isvalid = false
   end if

End Sub

您实际上并不需要遍历列表并单独评估所有控件。

哪个验证器控件用于将列表框选择限制为2？

3 个答案: