Question

DropDownLists上每个项目有两个Repeater。

我将两个列表绑定到转发器DataBound上的两个不同列表。

两个列表都有一个OnSelectedIndexChanged事件处理程序，它根据DropDownLists中的选择进行一些计算。两个列表也有AutoPostBack="True"。

我需要立即更新计算。所以我在转发器上添加了另一个数据绑定 - 在列表的事件处理程序上。

然而，这是问题 - 转发器将选择“重置”为-1，最终显示DropDownLists中的第一项。

如何在数据绑定后确保选择保留？

这是转发器结构：

            <asp:Repeater runat="server" ID="rptCart">
                <ItemTemplate>
                    <tr>
                        <td class="size"><div><asp:DropDownList runat="server" ID="_selectSize" AutoPostBack="true" OnSelectedIndexChanged="selectChange" EnableViewState="true" TabIndex="<%#Container.ItemIndex%>"></asp:DropDownList></div></td>
                        <td class="material"><div><asp:DropDownList runat="server" ID="_selectMaterial" AutoPostBack="true" OnSelectedIndexChanged="selectChange" EnableViewState="true" TabIndex="<%#Container.ItemIndex%>"></asp:DropDownList></div></td>
                    </tr>
                </ItemTemplate>
            </asp:Repeater>

转发器DataBound：

Protected Sub rptCart_ItemDataBound(sender As Object, e As System.Web.UI.WebControls.RepeaterItemEventArgs) Handles rptCart.ItemDataBound
    If e.Item.ItemType = ListItemType.AlternatingItem OrElse e.Item.ItemType = ListItemType.Item Then
        Dim sizeSelect As DropDownList = CType(e.Item.FindControl("_selectSize"), DropDownList)
        Dim materialSelect As DropDownList = CType(e.Item.FindControl("_selectMaterial"), DropDownList)

        sizeSelect.DataSource = sizeList
        sizeSelect.DataBind()
        materialSelect.DataSource = materialList
        materialSelect.DataBind()
    End If
End Sub

最后是DropDownLists事件处理程序：

Protected Sub selectChange(ByVal sender As DropDownList, ByVal e As System.EventArgs)
    Dim listing As New PriceListing
    Dim ddl As DropDownList
    Dim selectedIndex As Integer

    If sender.ID = "_selectSize" Then
        For Each rptrItem As RepeaterItem In rptCart.Items
            ddl = CType(rptrItem.FindControl("_selectMaterial"), DropDownList)
            If ddl.TabIndex = sender.TabIndex Then Exit For
        Next

        For Each listing In artDecoPricing
            If listing.Size = sender.SelectedValue Then Exit For
        Next

        selectedIndex = ddl.SelectedIndex
    ElseIf sender.ID = "_selectMaterial" Then
        For Each rptrItem As RepeaterItem In rptCart.Items
            ddl = CType(rptrItem.FindControl("_selectSize"), DropDownList)
            If ddl.TabIndex = sender.TabIndex Then Exit For
        Next

        For Each listing In artDecoPricing
            If listing.Size = ddl.SelectedValue Then Exit For
        Next

        selectedIndex = sender.SelectedIndex
    End If

    Select Case selectedIndex
        Case 0
            Cart.Order.Items(sender.TabIndex).PriceUnit = listing.Canvas
        Case 1
            Cart.Order.Items(sender.TabIndex).PriceUnit = listing.Acrylic
        Case 2
            Cart.Order.Items(sender.TabIndex).PriceUnit = listing.Framed
        Case 3
            Cart.Order.Items(sender.TabIndex).PriceUnit = listing.Framed
    End Select

    Cart.SaveOrder()

    rptCart.DataSource = Cart.Order.Items
    rptCart.DataBind()
End Sub

非常感谢你！

Answer 1

您可以存储旧选择：

Dim sizeSelect As DropDownList = CType(e.Item.FindControl("_selectSize"), DropDownList)
Dim materialSelect As DropDownList = CType(e.Item.FindControl("_selectMaterial"), DropDownList)
Dim sizeSelectedIndex = sizeSelect.SelectedIndex
Dim materialSelectedIndex = materialSelect.SelectedIndex
' do the databinding ... '
sizeSelect.SelectedIndex = If(sizeSelectedIndex < sizeSelect.Items.Count -1, sizeSelectedIndex, -1)
materialSelect.SelectedIndex = If(materialSelectedIndex < materialSelect.Items.Count -1, materialSelectedIndex, -1)

ASP.NET - 在转发器DataBound上保留DropDownList选择

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