vb.net - 中继器内部的 DropDownList SelectedindexChanged 不会触发

Question

我正在使用用户控制页面 (.ascx)。我有一个中继器，里面有 n DropDownList 和一些文本框。我需要触发 SelectedIndexChanged 事件以从文本框中获取值。

这是我得到的错误: “ddlEye_SelectedIndexChanged”不是“ASP.controls_claims_laborder_ascx”的成员。

HTML:

<asp:Repeater ID="rptProducts" runat="server">
    <HeaderTemplate>
        <tr class="Header">
            <td>Eye</td>
            <td>Tarrif</td>
            <td>Description</td>
            <td>Lab Price</td>
        </tr>
    </HeaderTemplate>
        <ItemTemplate>
            <tr>
                <td> 
                    <asp:DropDownList ID="ddlEye" runat="server" OnSelectedIndexChanged="ddlEye_SelectedIndexChanged" AutoPostBack="true">
                        <asp:ListItem Text="N/A" />
                        <asp:ListItem Text="Left" />
                        <asp:ListItem Text="Right" />
                    </asp:DropDownList>
                </td>
                <td>
                    <asp:TextBox ID="txtTariff" runat="server" ReadOnly="true" Text='<%# DataBinder.Eval(Container.DataItem, "Code") %>' />
                </td>
                <td>
                    <asp:TextBox ID="txtDescription" runat="server" ReadOnly="true" Text='<%# DataBinder.Eval(Container.DataItem, "Description") %>' />
                </td>
                <td>
                    <asp:TextBox ID="txtLabPrice" runat="server" ReadOnly="true" Text='<%# DataBinder.Eval(Container.DataItem, "Invoice") %>' />
                </td>
            </tr>
        </ItemTemplate>
</asp:Repeater>

代码隐藏:

Private Sub ddlEye_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles ddlEye.SelectedIndexChanged
        Dim dEye As DropDownList = DirectCast(sender, DropDownList)

        If ddlEye.SelectedItem.Value = "Right" Then
            lblLeftLensDesc.Text = "Description of the left lens"
            lblRightLensDesc.Text = dEye.SelectedItem.Text
        ElseIf ddlEye.SelectedItem.Value = "Left" Then
            lblLeftLensDesc.Text = dEye.SelectedItem.Text
            lblRightLensDesc.Text = "Description of the right lens"
        Else
            lblLeftLensDesc.Text = "Description of the left lens"
            lblRightLensDesc.Text = "Description of the right lens"
        End If
End Sub

我也尝试过为 DropDownList 动态创建事件，但仍然不起作用。

Private Sub rptProducts_ItemDataBound(sender As Object, e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles rptProducts.ItemDataBound
        Dim dlEye As DropDownList = e.Item.FindControl("ddlEye")
        Dim txtDesc As TextBox = e.Item.FindControl("txtDescription")

        If Not dlEye Is Nothing AndAlso Not txtDesc Is Nothing Then
            dlEye.SelectedIndexChanged += New EventHandler(ddlEye_SelectedIndexChanged)
            dlEye.SelectedValue = txtDesc.Text
        End If

End Sub

中继器绑定(bind)代码:

 Private Sub loadLineItems(ByVal strTransactionID As String)
     Dim objLineItems As ArrayList = Managers.LineItem.GetLineItems(CInt(strTransactionID))

     If objLineItems.Count > 0 Then
         rptProducts.DataSource = objLineItems
         rptProducts.DataBind()
     Else
         rptProducts.DataSource = Nothing
         rptProducts.DataBind()
     End If
End Sub

If Not IsPostBack Then
    loadLineItems(Session("pstrTransactionID").ToString())
End If

Answer 1

This is the error that I get: 'ddlEye_SelectedIndexChanged' is not a member of 'ASP.controls_claims_laborder_ascx'.

原因是您的事件处理程序是Private。您要么需要使其成为 Protected 或 Public，要么您不能在 ascx 上以声明方式添加事件处理程序，但您需要在代码隐藏中以编程方式添加它(通过使用 Handles 或 AddHandler)。

例如:

Protected Sub ddlEye_SelectedIndexChanged(sender As Object, e As System.EventArgs) 
    ' ...
End Sub

或(注意句柄)

Private Sub ddlEye_SelectedIndexChanged(sender As Object, e As System.EventArgs) Handles ddlEye.SelectedIndexChanged
    ' ...
End Sub

这里你需要从 ascx 中删除以下内容

OnSelectedIndexChanged="ddlEye_SelectedIndexChanged"

旁注:你使用

AddHandler dlEye.SelectedIndexChanged, AddressOf ddlEye_SelectedIndexChanged

在 VB.NET 中。

更新

Thank you so much it worked. Perhaps you can help me with another issue, I want to get the textbox value in the same row as the DropDownList when setectedIndex changes?

您可以通过NamingContainer 获取RepeaterItem，您只需要对其进行相应的转换即可。然后您可以使用 FindControl("ID") 获取 TextBox:

Protected Sub ddlEye_SelectedIndexChanged(sender As Object, e As System.EventArgs) 
        Dim dEye As DropDownList = DirectCast(sender, DropDownList)
        Dim item = DirectCast(dEye.NamingContainer, RepeaterItem)
        Dim txtTariff = DirectCast(item.FindControl("txtTariff"), TextBox)
        ' ...
End Sub