Question

This must be something that a lot of people have done. Basically, it’s a custom GridView (i.e. inherited control) with the ability to update all rows at once. I’ve tried putting the “update all” button in various places (footer, pager, outside the grid), but it looks neatest (to me) when the button is in an extra row as the last row of the GridView.

NB: The pager row is not a suitable place for this button because this custom control could be used in a situation where paging is false. Similarly, the normal footer may be required for some other purpose (e.g. totals).

Here’s my code for putting the button in the correct place (with apologies for the terse variables etc.):

    protected override void OnPreRender(EventArgs e)
    {
        base.OnPreRender(e);
        //Add an extra row to the table...
        if (_updateAllEnabled)
        {
          GridViewRow r = base.CreateRow(-1, -1, DataControlRowType.Footer, DataControlRowState.Normal);
          Button btn = new Button();
          TableCell c = new TableCell();
          btn.ID = "UpdateAllButton";    // tried with and without this line
          btn.Text = "Update All";
          btn.Click += new EventHandler(UpdateAll);
          r.Cells.Add(c);
          c.Controls.Add(btn);
          Table t = this.Controls[0] as Table;
          c.ColumnSpan = this.Columns.Count;
          t.Rows.Add(r);           
      }
    }

This gives the appearance that I want, but the click event (UpdateAll) does not fire.

I assume that the stuff is being added too late in the life cycle (PreRender), but where else can I do this to ensure that the row is at the end of the GridView? I also thought that there might be trouble identifying the button, so I tried setting the ID. In any case, the ID in the generated HTML looks OK (consistent with “working” buttons in the pager row.

Is there a way for me to achieve this or am I attempting the impossible?

Answer 1

It would be easy to add an extra row into the grid. But the difficulty in your requirement is that the GridView’s RowCollection should not contain this row since that would be error-prone. It should also be the very last row even if paging is enabled. This is (afaik) not possible.

Hence i’ve chosen to extend the pager with this functionality.

I’ll add this as separate answer since my other is already too detailed and describes two different ways(footer,pager) to add controls to a GridView without extending it.

This approach extends a GridView as in your own requirement and is similar to my other pager-approach. But it’s cleaner and only adds the additional row to the BottomPager. It woks also for every setting(AllowPaging=false,Pager-Position: Top,Bottom,BottomTop):

[DefaultProperty("EnableUpdateAll")]
[ToolboxData("<{0}:UpdateGridView runat=server></{0}:UpdateGridView>")]
public class UpdateGridView : GridView
{
    [Bindable(true)]
    [Category("Appearance")]
    [DefaultValue("true")]
    [Localizable(true)]
    public bool EnableUpdateAll
    {
        get
        {
            Object val = ViewState["EnableUpdateAll"];
            return ((val == null) ? true : (bool)val);
        }

        set
        {
            ViewState["EnableUpdateAll"] = value;
        }
    }

    private bool OriginalAllowPaging
    {
        get
        {
            Object val = ViewState["OriginalAllowPaging"];
            return (bool)val;
        }

        set
        {
            ViewState["OriginalAllowPaging"] = value;
        }
    }

    private PagerPosition OriginalPagerPosition
    {
        get
        {
            Object val = ViewState["OriginalPagerPosition"];
            return (PagerPosition)val;
        }

        set
        {
            ViewState["OriginalPagerPosition"] = value;
        }
    }

    protected override void OnInit(System.EventArgs e)
    {
        if (ViewState["OriginalPagerPosition"] == null)
            OriginalPagerPosition = base.PagerSettings.Position;
        if(OriginalPagerPosition != PagerPosition.Bottom)
            PagerSettings.Position=PagerPosition.TopAndBottom;
        if (ViewState["OriginalAllowPaging"] == null)
            OriginalAllowPaging = base.AllowPaging;
        base.AllowPaging = true;
    }

    protected override void OnRowCreated(GridViewRowEventArgs e)
    {
        switch (e.Row.RowType)
        {
            case DataControlRowType.Pager:
                //check if we are in BottomPager
                if (this.Rows.Count != 0 && this.EnableUpdateAll)
                {
                    Button btnUpdate = new Button();
                    btnUpdate.ID = "BtnUpdate";
                    btnUpdate.Text = "Update";
                    btnUpdate.Click += new EventHandler(UpdateAll);
                    var tblPager = (Table)e.Row.Cells[0].Controls[0];
                    var row = new TableRow();
                    var cell = new TableCell();
                    cell.ColumnSpan = tblPager.Rows[0].Cells.Count;
                    cell.Controls.Add(btnUpdate);
                    row.Cells.Add(cell);
                    tblPager.Rows.Add(row);
                }
                break;
        }
    }

    protected override void OnPreRender(EventArgs e)
    {
        bool bottomPagerVisible = 
            OriginalAllowPaging && 
            PageCount > 1 && 
            (OriginalPagerPosition == PagerPosition.Bottom || OriginalPagerPosition == PagerPosition.TopAndBottom);
        BottomPagerRow.Visible = bottomPagerVisible || EnableUpdateAll;
        var tblBottomPager = (Table)BottomPagerRow.Cells[0].Controls[0];
        tblBottomPager.Rows[0].Visible = bottomPagerVisible;
    }

    private void UpdateAll(Object sender, EventArgs e)
    {
        // do something...
    }
}