Hello,

Alright so to do this we need to add the checkbox to the header template before the column is even created... so before I assigned the datasource property of the grid I needed to setup the template column. <In the snippet you added I am guessing you did that in the InitializeLayout event handler or after you've set the DataSource and called DataBind and that is too late to hook items into the HeaderTemplate, do it in the Page's OnInit instead.>

So here's the code to do that column setup:

C#

    protected override void OnInit(EventArgs e)

    {

        base.OnInit(e);

        // Create a templated column

        TemplatedColumn col = new TemplatedColumn(true);

        this.UltraWebGrid1.DisplayLayout.Bands[0].Columns.Add(col);

        col.Key = "CheckBoxCol";

        col.Header.Caption = "";

        GridHeaderTemplate tempHeader = new GridHeaderTemplate();

        // Set the header template.

        col.HeaderTemplate = tempHeader;

        this.UltraWebGrid1.DataSource = LoadGrid();

        this.UltraWebGrid1.DataBind();

    }

VB.NET

Protected Overrides Sub OnInit(ByVal e As EventArgs)

    MyBase.OnInit(e)

    ' Create a templated column 
    Dim col As New TemplatedColumn(True)
   
    Me.UltraWebGrid1.DisplayLayout.Bands(0).Columns.Add(col)
    col.Key = "CheckBoxCol"
    col.Header.Caption = ""
   
    Dim tempHeader As New GridHeaderTemplate()
    ' Set the header template.
    col.HeaderTemplate = tempHeader
   
    Me.UltraWebGrid1.DataSource = LoadGrid()
    Me.UltraWebGrid1.DataBind()
End Sub

So now what does my GridHeaderTemplate look like:

C#

public class GridHeaderTemplate : ITemplate

{

    public void InstantiateIn(Control container)

    {

        // Cast the container to a HeaderItem

        HeaderItem headerItem = (HeaderItem)container;

        CheckBox checkBox = new CheckBox();

        CheckBox cb = new CheckBox();

        cb.ID = "headerCB";

        cb.Attributes.Add("onclick", "HeaderCheckedChanged();");

        headerItem.Controls.Add(cb);

    }

}

VB.NET

Public Class GridHeaderTemplate
    Implements ITemplate
   
    Public Sub InstantiateIn(ByVal container As Control)
        ' Cast the container to a HeaderItem
        Dim headerItem As HeaderItem = DirectCast(container, HeaderItem)
       
        Dim checkBox As New CheckBox()
       
        Dim cb As New CheckBox()
        cb.ID = "headerCB"
        cb.Attributes.Add("onclick", "HeaderCheckedChanged();")
        headerItem.Controls.Add(cb)
    End Sub
End Class

 Next I setup the Cell Template dynamically in the WebGrid's InitializeLayout event handler:

C#

TemplatedColumn col = (TemplatedColumn)(e.Layout.Bands[0].Columns.FromKey("CheckBoxCol"));

PlaceHolderTemplate tempCell = new PlaceHolderTemplate();

// Set the cell template.

col.CellTemplate = tempCell;

// make the checkbox the last column of band 0.

col.Move(e.Layout.Bands[0].Columns.Count - 1);

this.ClientScript.RegisterClientScriptBlock(this.GetType(), "CheckBoxKey", "<script type='text/javascript'>var headerCheckBoxID = '" + col.HeaderItem.FindControl("headerCB").ClientID + "';</script>");

this.ClientScript.RegisterClientScriptBlock(this.GetType(), "GridKey", "var gridID = '" + this.UltraWebGrid1.ClientID + "';", true);

VB.NET

Dim col As TemplatedColumn = DirectCast((e.Layout.Bands(0).Columns.FromKey("CheckBoxCol")), TemplatedColumn)

Dim tempCell As New PlaceHolderTemplate()
' Set the cell template.
col.CellTemplate = tempCell

' make the checkbox the last column of band 0.
col.Move(e.Layout.Bands(0).Columns.Count - 1)

Me.ClientScript.RegisterClientScriptBlock(Me.[GetType](), "CheckBoxKey", "<script type='text/javascript'>var headerCheckBoxID = '" + col.HeaderItem.FindControl("headerCB").ClientID + "';</script>")
Me.ClientScript.RegisterClientScriptBlock(Me.[GetType](), "GridKey", "var gridID = '" + Me.UltraWebGrid1.ClientID + "';", True)

The PlaceHolderTemplate used for the Cell Template should be awfully familiar now that we've seen the header...

C#

public class PlaceHolderTemplate : ITemplate

{

    public void InstantiateIn(Control container)

    {

        // Cast the container to a CellItem

        CellItem cellitem = (CellItem)container;

        CheckBox cb = new CheckBox();

        cb.ID = "cellCB";

        cellitem.Controls.Add(cb);

    }

}

VB.NET

Public Class PlaceHolderTemplate
    Implements ITemplate
    Public Sub InstantiateIn(ByVal container As Control)
        ' Cast the container to a CellItem
        Dim cellitem As CellItem = DirectCast(container, CellItem)
        Dim cb As New CheckBox()
        cb.ID = "cellCB"
        cellitem.Controls.Add(cb)
    End Sub
End Class

Now I told the Header Checkbox to call a javascript function when its onclick fires... so here's the js I used to toggle the checkbox:

<script type="text/javascript">

    function HeaderCheckedChanged(){

        var headerCheckBox = document.getElementById(headerCheckBoxID);

        var grid = igtbl_getGridById(gridID);

        for (i = 0; i < grid.Rows.length; i++)

        {

            grid.Rows.getRow(i).getCellFromKey("CheckBoxCol").getElement().children[0].checked = headerCheckBox.checked;

        }

    }

</script>

The javascript function can be written in several ways and accomplish the same task this is merely one way to accomplish this task.

Also as you can see in the code behind I registered a script block to render the grid's id to the client for use in my HeaderCheckedChanged function and I also threw the Header CheckBox's Id out to the client as well.  You can use a stringbuilder and do this part a little neater but I think the point of what I've done to solve the task presented has been displayed in these code snippets. 

What have others done in the past to solve this task?

 EDIT: Updated code snippets to handle OnInit instead of Page_Load as page load was again too late in the Page's Lifecycle.