Add TemplateColumn of CheckBoxes to DataGrid programmatically

Question

in my procedure in code-behind I am trying to create a DataGrid with autoGenerateColumns = true :

            DataGrid NewDg = new DataGrid();
            NewDg.AutoGenerateColumns = true;
            NewDg.Width = Unit.Percentage(100.00);
            NewDg.DataSource = ds;
            NewDg.DataBind(); 

I need to also add another column (TemplateColumn maybe) of CheckBoxes to this Grid. Do you know how to do that??

I have tried that:

               TemplateColumn t = new TemplateColumn();
            CheckBox c = new CheckBox();
            t.ItemTemplate = (ITemplate)c;
            NewDg.Columns.Add(t);

I get the following exception trace:

System.InvalidCastException: Unable to cast object of type 'System.Web.UI.WebControls.CheckBox' to type 'System.Web.UI.ITemplate'. at Default2.DataGrid1_ItemDataBound(Object sender, DataGridItemEventArgs e) in c:\Users\saher\Documents\TreeTest\TreeDemo\Default2.aspx.cs:line 116 at System.Web.UI.WebControls.DataGrid.OnItemDataBound(DataGridItemEventArgs e) at System.Web.UI.WebControls.DataGrid.CreateItem(Int32 itemIndex, Int32 dataSourceIndex, ListItemType itemType, Boolean dataBind, Object dataItem, DataGridColumn[] columns, TableRowCollection rows, PagedDataSource pagedDataSource) at System.Web.UI.WebControls.DataGrid.CreateControlHierarchy(Boolean useDataSource) at System.Web.UI.WebControls.BaseDataList.OnDataBinding(EventArgs e) at System.Web.UI.WebControls.BaseDataList.DataBind() at Default2.BindData() in c:\Users\saher\Documents\TreeTest\TreeDemo\Default2.aspx.cs:line 44 

Answer 1

You'll need to add the checkbox to your template container instead of casting to it.

Here's an article on adding templates dynamically:
http://msdn.microsoft.com/en-us/library/aa712868(VS.71).aspx

Answer 2

If this additional column is always present, is there a reason why you can't add it to the grid in design view as opposed to code? Or is it only displayed under certain conditions?

If not, you can specify your additional column in the design view and have the autoGenerateColumns add the rest of the columns at runtime.

Answer 3

Hi,

Do you have to create it in code-behind? If so check in http://msdn.microsoft.com/en-us/library/system.web.ui.templatebuilder.aspx. Otherwise you can declare it as:

<asp:DataGrid id="MyGrid" runat="server">
    <Columns>
        <asp:TemplateColumn>
            <HeaderTemplate><b>Check Me!</b></HeaderTemplate>
            <ItemTemplate>
                <asp:CheckBox runat="server" />
            </ItemTemplate>
        </asp:TemplateColumn>
    </Columns>    
</asp:DataGrid>