Tips & Tricks

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

ledo_moon — Thu, 08 Oct 2009 23:03:55 GMT

Please check this solution

http://ledomoon.blogspot.com/2009/04/show-grid-view-header-and-footer-when.html

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

jstranger — Sat, 26 Sep 2009 13:01:20 GMT

I am really glad this thread is still running! For several years I have used the relatively crude approach of declaring a GridView with a FooterTemplate on each column for inserts and an EmptyDataTemplate containing identical controls for inserting when there is no starting data. Then in code behind I test if the row count is 0 and if so find each control from the EmptyData template and if not do the same for the FooterRow. All works but very irritating.

So now I am trying to build a custom GridView using the approach to override CreateChildControls broadly as set out by CISCBrain with a few slight modifications (in addition I am also autogenerating command columns but these work OK so I have removed this processing from the code below). [BTW I am not interested in any crude hack such as binding to an empty DataTable]

Protected Overrides Function CreateChildControls(ByVal dataSource As System.Collections.IEnumerable, ByVal dataBinding As Boolean) As Integer
        Dim numRows As Integer = MyBase.CreateChildControls(dataSource, dataBinding)
        If numRows = 0 And (ShowHeaderWhenEmpty Or ShowFooterWhenEmpty) Then
            Dim tab As Table = Me.CreateChildTable()
            Dim flds As DataControlField() = New DataControlField(Me.Columns.Count - 1) {}
            Me.Columns.CopyTo(flds, 0)
            If ShowHeaderWhenEmpty Then
                _headerRow = MyBase.CreateRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal)
                Me.InitializeRow(_headerRow, flds)
                tab.Rows.Add(_headerRow)
                MyBase.OnRowCreated(New GridViewRowEventArgs(_headerRow))
            End If
            If Insertable And ShowFooterWhenEmpty Then
                _footerRow = MyBase.CreateRow(-1, -1, DataControlRowType.Footer, DataControlRowState.Normal)
                Me.InitializeRow(_footerRow, flds)
                Me.ShowFooter = True
                tab.Rows.Add(_footerRow)
                MyBase.OnRowCreated(New GridViewRowEventArgs(_footerRow))
            End If
            Me.Controls.Clear()
            Me.Controls.Add(tab)
        End If
        Return numRows
    End Function

And I have the following properties:

Protected _headerRow As GridViewRow = Nothing
    Public Overloads Overrides ReadOnly Property HeaderRow() As GridViewRow
        Get
            If Not MyBase.HeaderRow Is Nothing Then
                Return MyBase.HeaderRow
            Else
                Return _headerRow
            End If
        End Get
    End Property
    Protected _footerRow As GridViewRow = Nothing
    Public Overloads Overrides ReadOnly Property FooterRow() As GridViewRow
        Get
            If Not MyBase.FooterRow Is Nothing Then
                Return MyBase.FooterRow
            Else
                Return _footerRow
            End If
        End Get
    End Property

All this works and I can retrieve values from the controls in the footer row whether there is starting data or not.

However, the problem I have is if the footer includes databound controls such as DropDownLists. In this case, I get an error that the Bind (or Eval) can only be used i the context of a databound control. This did not happen when I was using the EmptyDataTemplate for this purpose, so it would seem that somehow the footer row is not getting initialized properly. What do I need to do to ensure tat the footer is properly initialized and databound?

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

Ptpro — Wed, 17 Jun 2009 21:04:15 GMT

I ran into the same problem where me.InitializeRow is giving an object reference error. The solution has to do with dimensioning the fields() variable. You probably had the code:

Dim fields(Me.Columns.Count) As DataControlField

It should be

Dim fields(Me.Columns.Count - 1) As DataControlField

Many thanks to CISCBrain for posting the code.

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

emendes — Tue, 28 Apr 2009 09:43:57 GMT

Check This link

http://geekswithblogs.net/dotNETvinz/archive/2009/03/11/tiptrick-show-header-and-footer-of-gridview-when-no-data.aspx

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

iamacyborg — Fri, 24 Apr 2009 23:44:17 GMT

This is how I handled it. I think this is simpler than the other "override the GridView control" methods that have been posted here.

    public class OtisGridView : GridView {
        private bool _emptyGrid = false;

        protected override void PerformDataBinding(IEnumerable data) {
            _emptyGrid = false;

            if (data is DataView) {
                DataView view = (DataView)data;
                DataTable table = view.Table;

                if (table.Rows.Count == 0) {
                    // create a "dummy" row to prevent
                    // "empty" state
                    DataRow row = table.NewRow();
                    table.Rows.Add(row);
                    _emptyGrid = true;
                }
            }

            base.PerformDataBinding(data);
        }

        protected override void InitializeRow(GridViewRow row, DataControlField[] fields)
        {
            if (_emptyGrid && row.RowType == DataControlRowType.DataRow) {
                row.Visible = false;
            }
            else {
                base.InitializeRow(row, fields);
            }
        }
    }

Edit: I see above somone already posted something very similar, only using events. That is good if you have just one gridview. This is good if you are using it in many places in your site.

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

Pak514 — Wed, 22 Apr 2009 15:30:20 GMT

azamsharp:
I am saying that when the following command gets executed does it access the database: SqlDataSource.SelectCommand = "select '' as f1,'' as f2,'' as f3,'' as f4,'' as f5,'' as f6 from dual";

My bad, I thought you were talking about the OP solution.

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

azamsharp — Wed, 22 Apr 2009 14:09:46 GMT

I am saying that when the following command gets executed does it access the database: SqlDataSource.SelectCommand = "select '' as f1,'' as f2,'' as f3,'' as f4,'' as f5,'' as f6 from dual";

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

Pak514 — Wed, 22 Apr 2009 13:24:14 GMT

azamsharp:
The above solution will end up with one extra database fetching!

What do you mean, I don't understand your statement can you please elaborate. The complete solution works well with .net 2.0 GridView when no records are present in DataTable and DataSet. No problems encountered thus far.

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

azamsharp — Tue, 21 Apr 2009 18:08:49 GMT

The above solution will end up with one extra database fetching!

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

Pak514 — Tue, 21 Apr 2009 16:30:40 GMT

Very nice solution, beats adding a dummy row to a dataset and binding it that way. Thanks.

Re: simplest way - eyad

gemsgems — Mon, 23 Mar 2009 16:59:47 GMT

the simple way to put select command of SqlDataSource control to get default row as this :

SqlDataSource.SelectCommand = "select '' as f1,'' as f2,'' as f3,'' as f4,'' as f5,'' as f6 from dual";

where :

f1,f2,... the name of columns that uses

SqlDataSource is the control that bind your DataGrid

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

azamsharp — Fri, 21 Nov 2008 18:39:19 GMT

Just bind it to an empty DataSet or DataTable and the headers and footers will be displayed

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

y34h — Fri, 21 Nov 2008 03:51:47 GMT

after a few suffering and some forum-surfing i said to my self : "AAHHH what the hell !!, i'll do it my self XDD"

so... here's my solution

	bool empty = false;

	protected void ObjectDataSource1_Selected(object sender, ObjectDataSourceStatusEventArgs e)
	{
		DataTable t = (DataTable)e.ReturnValue;
		if (t.Rows.Count == 0)
		{
			t.Rows.Add(new object[] { });
			empty = true;
		}
	}

	protected void GridView1_DataBound(object sender, EventArgs e)
	{
		if (empty) GridView1.Rows[0].Visible = false;
	}

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

Kriswd40 — Wed, 03 Sep 2008 18:49:13 GMT

Several years late, but this is a much simpler way to get the heading to display:

datagridName.DataSource = new DataTable();

datagridName.DataBind();

Works with datagrid, I have not tested with gridView.

Re: Solution: Show Header/Footer of Gridview with Empty Data Source

faruk2011 — Wed, 23 Jul 2008 11:28:02 GMT

excellent solution. working properly.

Thank you very much.

Faruk Ahmed