2 Dropdownlists in Gridview cause error: Databinding methods such as Bind() can only be used in the context of a databound control

Question

虽然之前似乎讨论过这个问题，但我无法在我的案例中申请 given help:

我在 Gridview 的编辑模板中有 2 个下拉列表（DDL1、DDL2），它们绑定到 SQLDataSource。 DDL2 取决于 DDL1 的选定值。

如果我将填充 DropDownLists 的 SQLDataSources 放在顶层，即使我正确地寻址它 (Gridview$DDL1ControlID)，也找不到 DDL2 的 ControlParameter 的 ControlID。因此，我将 SQLDataSources 放在 Gridview 的编辑模板中。现在，如果我进入给定记录的编辑模式，两个 DropDownLists 都会正确填充；如果我更改 DDL1 的索引，DDL2 不会自动更新，因为 DDL2 已将 AutoPostBack 设置为 false。一旦我将 AutoPostBack 设置为 true，就会抛出错误 "Databinding methods such as Eval(), XPath(), and Bind() can only be used in the "。

    <asp:GridView runat="server" ID="Gridview1" 
                  DataSourceID="Milestones" 
                  DataKeyNames="ID"
                  OnRowEditing="OnRowEditing"
                  OnRowDataBound="OnRowDataBoundMS"
                  OnSelectedIndexChanged="OnSelectedIndexChangedMS">
....
            <asp:templatefield HeaderText="Default Owner Group" ItemStyle-HorizontalAlign="center">
            <ItemTemplate>
                <asp:Label runat="server" Text='<%# Bind("DefaultOwnerGroup") %>' id="LabelDefaultOwnerGroup" Font-Size="12px" Width="50px"/>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:SqlDataSource runat="server" id="OwnerGroups" ProviderName="System.Data.SqlClient"
                    ConnectionString="Data Source=XXXXX"    
                    SelectCommand="select function, 2 as ord
                                   from Staff
                                   where function is not null
                                   group by function
                                   union all
                                   select 'select' as function, 0 as ord
                                   union all
                                   select '-----' as function, 1 as ord
                                   order by ord, function">
                </asp:SqlDataSource>
                <asp:DropDownList runat="server" id="DDOwnerGroup" Text='<%# Bind("DefaultOwnerGroup") %>' DataSourceID="OwnerGroups" DataTextField="function" DataValueField="function" Font-Size="12px" Width="80px" AutoPostBack="true"/>
            </EditItemTemplate>
        </asp:templatefield>

        <asp:templatefield HeaderText="Default Owner" ItemStyle-HorizontalAlign="center">
            <ItemTemplate>
                <asp:Label runat="server" Text='<%# Bind("DefaultOwner") %>' id="LabelDefaultOwner" Font-Size="12px" Width="50px"/>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:SqlDataSource runat="server" id="Owner" ProviderName="System.Data.SqlClient" 
                    ConnectionString="Data Source=XXXXX"    
                    SelectCommand="select Name, UserID
                                   from Staff
                                   where function = @OwnerGroup
                                   union all
                                   select Null as Name, Null as UserID
                                   order by Name">
                <SelectParameters>
                    <asp:ControlParameter ControlID="DDOwnerGroup" PropertyName="SelectedValue" Name="OwnerGroup"  Type="String" />
                </SelectParameters>
                </asp:SqlDataSource>
                <asp:DropDownList runat="server" id="DDOwner" Text='<%# Bind("DefaultOwner") %>' Width="100px" DataSourceID="Owner" DataTextField="Name" DataValueField="UserID" Font-Size="12px"/>
            </EditItemTemplate>
        </asp:templatefield>

Answer 1

我像这样在 OnRowDataBound 事件中绑定 DropdownLists：

            <asp:templatefield HeaderText="Default Owner Group" ItemStyle-HorizontalAlign="center">
            <ItemTemplate>
                <asp:Label runat="server" Text='<%# Bind("DefaultOwnerGroup") %>' id="LabelDefaultOwnerGroup" Font-Size="12px" Width="50px"/>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:Label runat="server" Text='<%# Bind("DefaultOwnerGroup") %>' id="LabelDefaultOwnerGroupEdit" Visible="false"/>
                <asp:SqlDataSource runat="server" id="OwnerGroups" ProviderName="System.Data.SqlClient"
                    ConnectionString="Data Source=XXXXX"    
                    SelectCommand="...">
                </asp:SqlDataSource>
                <asp:DropDownList runat="server" id="DDOwnerGroup" DataSourceID="OwnerGroups" DataTextField="funcion" DataValueField="funcion" Font-Size="12px" Width="80px" AutoPostBack="true"/>
            </EditItemTemplate>
        </asp:templatefield>

        <asp:templatefield HeaderText="Default Owner" ItemStyle-HorizontalAlign="center">
            <ItemTemplate>
                <asp:Label runat="server" Text='<%# Bind("DefaultOwner") %>' id="LabelDefaultOwner" Font-Size="12px" Width="50px"/>
            </ItemTemplate>
            <EditItemTemplate>
                <asp:Label runat="server" Text='<%# Bind("DefaultOwner") %>' id="LabelDefaultOwnerEdit" Visible="false"/>
                <asp:SqlDataSource runat="server" id="Owner" ProviderName="System.Data.SqlClient" 
                    ConnectionString="Data Source=XXXXX"    
                    SelectCommand="...."
                <SelectParameters>
                    <asp:ControlParameter ControlID="DDOwnerGroup" PropertyName="SelectedValue" Name="OwnerGroup"  Type="String" />
                </SelectParameters>
                </asp:SqlDataSource>
                <asp:DropDownList runat="server" id="DDOwner" Width="100px" DataSourceID="Owner" DataTextField="Name" DataValueField="UserID" Font-Size="12px"/>
            </EditItemTemplate>
        </asp:templatefield>

protected void OnRowDataBoundMS(object sender, GridViewRowEventArgs e)
{
    if (e.Row.RowType == DataControlRowType.DataRow)
    {
        if ((e.Row.RowState & DataControlRowState.Edit) > 0)
        {
            DropDownList DDL1 = e.Row.FindControl("DDOwnerGroup") as DropDownList;
            DropDownList DDL2 = e.Row.FindControl("DDOwner") as DropDownList;
            Label LBL1 = e.Row.FindControl("LabelDefaultOwnerGroupEdit") as Label;
            Label LBL2 = e.Row.FindControl("LabelDefaultOwnerEdit") as Label;
            DDL1.SelectedValue = Convert.ToString(LBL1.Text);
            DDL2.DataBind();
            DDL2.SelectedValue = Convert.ToString(LBL2.Text);
        }
    }
}

2 Dropdownlists in Gridview cause error: Databinding methods such as Bind() can only be used in the context of a databound control

2 Dropdownlists in Gridview cause error: Databinding methods such as Bind() can only be used in the context of a databound control

asp.net

data-binding

gridview

sqldatasource

drop-down-menu