无法在 TemplateField SELECT 语句中从 GridView 获取/使用 ControlParamete

Question

我有一个简单的GridView(ID为'GridViewAttribs'(，它显示数据库中的一些值。

在我的 GridViewAttribs 中，我希望有一个(嵌套的？ListView，但由于某种原因，我无法使用asp：ControlParameter ControlID="GridViewAttribs"属性名称，因为我的(嵌套(ListView中没有返回任何结果。

如果我不使用 ControlParameter 并为列表视图硬编码我的 SELECT 语句，则一切按预期工作。

这是我的代码：

<asp:SqlDataSource ID="SqlDataSourceAttribHeadings" runat="server" 
    ConnectionString="<%$ ConnectionStrings:customer_support_devConnectionString %>" 
    ProviderName="<%$ ConnectionStrings:customer_support_devConnectionString.ProviderName %>" 
    SelectCommand="SELECT equipment_attrib_heading_id, equipment_model_id, equipment_attrib_name FROM equipment_new_attrib_headings WHERE (equipment_model_id = @equipment_model_id) AND (equipment_attrib_heading_deleted = 0) ORDER BY equipment_attrib_name">
    <SelectParameters>
        <asp:SessionParameter DefaultValue="" Name="equipment_model_id" 
            SessionField="EquipmentModelID" Type="Int32" />
    </SelectParameters>
</asp:SqlDataSource>
<asp:GridView ID="GridViewAttribs" runat="server" AutoGenerateColumns="False" 
    CellPadding="4" DataKeyNames="equipment_attrib_heading_id" 
    DataSourceID="SqlDataSourceAttribHeadings" ForeColor="#333333" GridLines="None" 
    style="margin-right: 0px">
    <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
    <Columns>
        <asp:BoundField DataField="equipment_attrib_heading_id" 
            HeaderText="equipment_attrib_heading_id" ReadOnly="True" 
            SortExpression="equipment_attrib_heading_id" />
        <asp:BoundField DataField="equipment_model_id" HeaderText="equipment_model_id" 
            SortExpression="equipment_model_id" />
        <asp:BoundField DataField="equipment_attrib_name" 
            HeaderText="equipment_attrib_name" SortExpression="equipment_attrib_name" />
        <asp:TemplateField HeaderText="equipment_attrib_value_details" SortExpression="equipment_attrib_value_details">
            <ItemTemplate>
                <asp:SqlDataSource ID="SqlDataSourceAttribValues" runat="server" 
                    ConnectionString="<%$ ConnectionStrings:customer_support_devConnectionString %>" 
                    ProviderName="<%$ ConnectionStrings:customer_support_devConnectionString.ProviderName %>" 
                    SelectCommand="SELECT [equipment_attrib_value_details] FROM [equipment_new_attrib_values] WHERE (equipment_attrib_heading_id = @head_id) AND (equipment_id = @equipment_id) AND (equipment_attrib_value_deleted = 0)">
                    <SelectParameters>
                        <asp:QueryStringParameter Name="equipment_id" QueryStringField="id" 
                            Type="Int32" />
                        <asp:ControlParameter ControlID="GridViewAttribs" 
                            Name="head_id" PropertyName="SelectedDataKey.Values[equipment_attrib_heading_id]" Type="Int32" />
                    </SelectParameters>
                </asp:SqlDataSource>
                <asp:ListView ID="ListViewAttribValues" runat="server" 
                    DataSourceID="SqlDataSourceAttribValues">
                    <EmptyDataTemplate>
                        <table runat="server" style="">
                            <tr><td>No data was returned.</td></tr>
                        </table>
                    </EmptyDataTemplate>
                    <ItemTemplate>
                        <tr style="">
                            <td><asp:Label ID="equipment_attrib_value_detailsLabel" runat="server" Text='<%# Eval("equipment_attrib_value_details") %>' /></td>
                        </tr>
                    </ItemTemplate>
                    <LayoutTemplate>
                        <table ID="itemPlaceholderContainer" runat="server" border="0" style="">
                            <tr ID="itemPlaceholder" runat="server">
                            </tr>
                        </table>
                    </LayoutTemplate>
                </asp:ListView>
            </ItemTemplate>
        </asp:TemplateField>

    </Columns>
</asp:GridView>

GridView 可以正常显示所有列，除了"equipment_attrib_value_details"列，我得到"未返回任何数据"。

但是，如果我取出调用@head_id的 asp：ControlParameter 并使用此硬编码的 SELECT 语句，那么我会看到正确的(尽管是硬编码的(值：

SelectCommand="SELECT [equipment_attrib_value_details] FROM [equipment_new_attrib_values] WHERE (equipment_attrib_heading_id = 3) AND (equipment_id = @equipment_id) AND (equipment_attrib_value_deleted = 0)">

因此，由于某种原因，似乎 GridViewAttribs 值"equipment_attrib_heading_id"没有被嵌套的 asp：ControlParameter 传递/拾取

万一不可开，我也尝试过替换：

PropertyName="SelectedDataKey.Values[equipment_attrib_heading_id]"

跟：

PropertyName="SelectedValue"

但这也没有解决问题，仍然没有返回数据。

如果有帮助，我正在使用带有ASP的Visual Studio 2010。NET4 (vb(。

Answer 1

您可以尝试的是使用隐藏字段并将该控件用于控制参数

<asp:TemplateField HeaderText="equipment_attrib_value_details" SortExpression="equipment_attrib_value_details">
                    <ItemTemplate>
                         <asp:HiddenField runat="server" ID="heading_id" Value='<%# Eval("equipment_attrib_heading_id") %>' />
                        <asp:SqlDataSource ID="SqlDataSourceAttribValues" runat="server" 
                            ConnectionString="<%$ ConnectionStrings:customer_support_devConnectionString %>" 
                            ProviderName="<%$ ConnectionStrings:customer_support_devConnectionString.ProviderName %>" 
                            SelectCommand="SELECT [equipment_attrib_value_details] FROM [equipment_new_attrib_values] WHERE (equipment_attrib_heading_id = @head_id) AND (equipment_id = @equipment_id) AND (equipment_attrib_value_deleted = 0)">
                            <SelectParameters>
                                <asp:QueryStringParameter Name="equipment_id" QueryStringField="id" Type="Int32" />
                                <asp:ControlParameter ControlID="heading_id" Name="head_id" PropertyName="Value" Type="Int32" />
                            </SelectParameters>
                        </asp:SqlDataSource>
                        <asp:ListView ID="ListViewAttribValues" runat="server" 
                            DataSourceID="SqlDataSourceAttribValues">
                            <EmptyDataTemplate>
                                <table id="Table2" runat="server" style="">
                                    <tr><td>No data was returned.</td></tr>
                                </table>
                            </EmptyDataTemplate>
                            <ItemTemplate>
                                <tr style="">
                                    <td><asp:Label ID="equipment_attrib_value_detailsLabel" runat="server" Text='<%# Eval("equipment_attrib_value_details") %>' /></td>
                                </tr>
                            </ItemTemplate>
                            <LayoutTemplate>
                                <table ID="itemPlaceholderContainer" runat="server" border="0" style="">
                                    <tr ID="itemPlaceholder" runat="server">
                                    </tr>
                                </table>
                 </LayoutTemplate>
         </asp:ListView>
     </ItemTemplate>
</asp:TemplateField>

Answer 2

这仅在HiddenField位于同一ItemTemplate内时才有效(似乎(。如果DataSource位于TemplateField之外的某个位置，如果要对控件进行数据填充，例如在 GridView 的另一列或字段上，则HiddenField将不起作用，因为它在技术上是隐藏的。

克服此问题的方法是代码隐藏。这是我的做法...

我有一个TemplateField指的是@StudentID，它实际上是另一个模板字段中的HiddenField。

        <asp:TemplateField HeaderText="Currently&lt;br/&gt;Tracking&lt;br/&gt;(past weeks)">
            <ItemTemplate>
                <asp:CheckBoxList ID="listWeeksTracking" runat="server" DataSourceID="sdsTETpastWeeks" DataTextField="WeekNo" DataValueField="WeekNo" 
                    OnDataBound="listWeeksTracking_DataBound" OnDataBinding="listWeeksTracking_DataBinding"></asp:CheckBoxList>
                    <br />
                <asp:SqlDataSource ID="sdsTETpastWeeks" runat="server" ConnectionString="<%$ ConnectionStrings:ATCNTV1ConnectionString %>"
                    SelectCommand="SELECT tb.WeekNo, ISNULL((SELECT TOP 1 ts.ETRTWtracking FROM tblTETMeetingStudent AS ts INNER JOIN tblTETMeeting AS tm ON tm.TETmeetingID = ts.TETmeetingID AND tm.WeekNo = tb.WeekNo WHERE ts.StudentID = @StudentID),0) AS Tracking FROM tblTETInstructionalTrainingBlocks AS tb WHERE tb.WeekNo <= @WeekNo AND tb.Active = 1 AND tb.YearNum = YEAR(@TETdate) ORDER BY tb.WeekNo">
                    <SelectParameters>
                        <asp:Parameter Name="StudentID" Type="string" />
                        <asp:ControlParameter ControlID="ddlWeekNo" Name="WeekNo" PropertyName="SelectedValue" Type="int16" />
                        <asp:ControlParameter ControlID="lblTETdate" Name="TETdate" Type="DateTime" />
                    </SelectParameters>
                </asp:SqlDataSource>
            </ItemTemplate>
            <ItemStyle HorizontalAlign="Center" />
            <HeaderStyle Wrap="False" />
        </asp:TemplateField>

所以我将@StudentID参数定义为一个简单的参数，而不是一个ControlParameter，它将无法在我的 GridView 中的其他地方拾取隐藏字段。

在代码隐藏 (C#( 中，我通过数据绑定捕获 Select 事件。在那里，我专门查找与我刚刚填充(或即将填充(的控件相关的行，然后查找 HiddenField。

protected void listWeeksTracking_DataBinding(object sender, EventArgs e)
{
    //set the parameter for the StudentID here as using hiddenfields does not work directly in asp.net, as they are hidden!
    CheckBoxList cbl1 = (CheckBoxList)sender;
    GridViewRow gvRow = (GridViewRow)cbl1.NamingContainer;
    if (gvRow != null)
    {
        SqlDataSource sdsTETpastWeeks = (SqlDataSource)gvRow.FindControl("sdsTETpastWeeks");
        HiddenField hfStudentID = (HiddenField)gvRow.FindControl("hfStudentID");
        if (hfStudentID != null) sdsTETpastWeeks.SelectParameters["StudentID"].DefaultValue = hfStudentID.Value.ToString();
    }
}

瞧！