停止在 FormView 命令上触发 DropDownList SelectedIndexChanged 事件

Question

我在 editItemTemplate 中有一个下拉列表。 Dropdownlist onSelectedIndexChanged 事件会在我想要的更改时触发。但是，当我提交表单时它也会触发。

********更新 ************ 根据下面的 Saechel 评论，我开始进一步调查。这里它描述了它可以做到。 http://blog.programmingsolution.net/net-windows-application/selectionchangecommitted-and-selectedindexchanged-events-system-nullreferenceexception-while-closing-windows-form/ 但是，我试过了，它甚至没有触发这个事件。 我检查了http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.dropdownlist(v=vs.110).aspx，但他们没有列出该事件。

我的目标是让用户输入值作为总计的百分比或实际作为实际吨数，然后来回切换。将插入数据库的最终值将以吨为单位。

我想要： a) 不触发“onSelectedIndexChanged”事件 b）一些如何确定我是否在同一个索引上并有一个 if 语句来跳过所有内容 c) 我不知道的更好的解决方法。

我尝试通过 ViewState 验证 Dropdown 的当前索引，如果相同但找不到​​值，则跳过代码。也许帮助我弄清楚如何获得该价值？搜索了一圈，找不到怎么做。 我试过：`var vs = ViewState["ddl_units"].ToString();以及我需要通过 FindControl 找到控件的其他一些变体

.aspx:

<asp:Panel ID="pnlRecycledMaterialsReceivedForm" runat="server" Visible="false">
    <asp:FormView ID="fvAddRecycledMaterialsReceived" runat="server" SkinID="annualReportFormview" EnableViewState="false"
        HeaderText="Selected Recycled Materials Received Detail" DataKeyNames="RecycleDetailId" DefaultMode="Insert"
        DataSourceID="odsRecycledMaterialsReceivedDetail" OnDataBound="fvAddRecycledMaterialsReceived_DataBound" 
        OnItemCommand="fvAddRecycledMaterialsReceived_ItemCommand" OnItemInserted="fvAddRecycledMaterialsReceived_ItemInserted"
        OnItemUpdated="fvAddRecycledMaterialsReceived_ItemUpdated" OnItemDeleted="fvAddRecycledMaterialsReceived_ItemDeleted">
        <EditItemTemplate>
            <asp:TextBox ID="tbxRecycledTotalWasteQuantity" runat="server" Text='<%# Bind("TotalWasteQuantity") %>' Width="64px"></asp:TextBox>
            <asp:TextBox ID="tbxRecycledWasteCommercialQuantity" runat="server" Text='<%# Bind("CommercialQuantity") %>' Width="64px"></asp:TextBox>
            <asp:TextBox ID="tbxRecycledWasteResidentialQuantity" runat="server" Text='<%# Bind("ResidentialQuantity") %>' Width="64px"></asp:TextBox>
            <asp:DropDownList ID="ddl_Units" runat="server" AutoPostBack="true" OnSelectedIndexChanged="ddl_Units_SelectedIndexChanged">
                <asp:ListItem Value="" Text="" Enabled="false" />
                <asp:ListItem Text="Tons" Value="1" />
                <asp:ListItem Text="Percent" Value="9" />
            </asp:DropDownList>
            <asp:LinkButton ID="lbtnWasteReceivedUpdate" runat="server" Text="Update" CommandName="Update"
                ValidationGroup="RecycledWasteReceivedDetail" Font-Bold="True" />&nbsp;
            <asp:LinkButton ID="lbtnWasteReceivedInsertCancel" runat="server" Text="Cancel" CausesValidation="False" CommandName="Cancel" />
        </EditItemTemplate>
    </asp:FormView>
</asp:Panel>

.cs:

protected void ddl_Units_SelectedIndexChanged(object sender, EventArgs e)
{
    TextBox tbxRecycledTotalWasteQuantity = (TextBox)fvAddRecycledMaterialsReceived.FindControl("tbxRecycledTotalWasteQuantity");
    TextBox tbxRecycledWasteResidentialQuantity = (TextBox)fvAddRecycledMaterialsReceived.FindControl("tbxRecycledWasteResidentialQuantity");
    var d_TotalWasteQuantity = Convert.ToDecimal(tbxRecycledTotalWasteQuantity.Text);
    ResidentialQuantity = Convert.ToDecimal(tbxRecycledWasteResidentialQuantity.Text);

    DropDownList ddl_units = (DropDownList)fvAddRecycledMaterialsReceived.FindControl("ddl_units");

    if (ddl_units.SelectedIndex.ToString() == "2")
    {
        //2 = percent
        //Take tb value and convert to percent
        //300/700 * 100
        tbxRecycledWasteResidentialQuantity.Text = ((ResidentialQuantity / d_TotalWasteQuantity) * 100).ToString();
        //ResidentialQuantity = ResidentialQuantity * (d_TotalWasteQuantity / 100);
    }
    else
    {
        //Else 'tons' was chosen. Convert value(%) to tons. 
        //700 * (43/100) = 301
        ResidentialQuantity = d_TotalWasteQuantity * (ResidentialQuantity / 100);
        tbxRecycledWasteResidentialQuantity.Text = ResidentialQuantity.ToString();
        //tbxRecycledWasteResidentialQuantity.Text = "Tons";
    }
}

Answer 1

尝试使用SelectionChangeCommitted Event。

这不会在表单加载时触发，而是在 selectionchange 时触发