Question

我有嵌套的转发器，嵌套转发器中的每个项目都有一个标签和一个按钮，我希望能够在点击按钮时访问label.text，我想我几乎就在那里，因为我可以返回单击转发器和嵌套转发器的索引，我只是在查找标签时遇到一些麻烦。

如果没有发布转发器代码，您可以帮助我。这是我点击按钮时的代码。

Protected Sub btnEditUser_Click(ByVal sender As Object, ByVal e As System.EventArgs)

    Dim btnEditUser As Button = DirectCast(sender, Button)
    Dim reClient As RepeaterItem = DirectCast(btnEditUser.NamingContainer.Parent.Parent, RepeaterItem)
    Dim reUser As RepeaterItem = DirectCast(btnEditUser.NamingContainer, RepeaterItem)
    Dim selectedClient As Integer = reClient.ItemIndex
    Dim selectedUser As Integer = reUser.ItemIndex

    Dim UserId As Label = DirectCast(reClients.Items(selectedClient).FindControl("lUserName"), Label)

    Response.Write(selectedClient & " " & selectedUser & " " & UserId.Text)

End Sub

我目前收到此错误'对象引用未设置为对象的实例。当我试图写下UserId.Text的值时，我觉得我在这一行中有点错误：

Dim UserId As Label = DirectCast(reClients.Items(selectedClient).FindControl("lUserName"), Label)

Answer 1

这只是猜测，但有时当你并非所有行都包含你正在寻找的控件时，你会得到这样的错误。通常，代码按顺序循环遍历行，首先命中不包含相关控件的标题行，然后失败。

Answer 2

这是一篇很好的MSDN文章 - 在名称containers的层次结构中查找控件。

Private Function FindControlRecursive(
    ByVal rootControl As Control, ByVal controlID As String) As Control

    If rootControl.ID = controlID Then
        Return rootControl
    End If

    For Each controlToSearch As Control In rootControl.Controls
        Dim controlToReturn As Control = 
            FindControlRecursive(controlToSearch, controlID)
        If controlToReturn IsNot Nothing Then
            Return controlToReturn
        End If
    Next
    Return Nothing
End Function

试试吧，

Dim UserId As Label =DirectCast(FindControlRecursive(repClient,"lUserName"),Label)

在嵌套转发器asp.net vb中单击按钮时获取标签值

2 个答案: