Using GridView Footer to Insert Record even if Empty

(Updated 10/29 to include ASP.Net example

A great thanks to Matt Berseth for his post on subclassing the GridView to show footers even when the GridView has no records. I used a C# to VB.Net converter to convert his excellent example and the net result is the code below (and includes the tweak/fix for persisting the Footer on PostBack). A few pecularities I noticed about using the Footer.

• I could not use two-way binding with my ObjectDataSource in the footer so I used the traditional code-behind approach with FindControl (insert does not use the DataSource at all)
• to find your controls you have to use MyGridView.Footer.FindControl(“aTextBox”)
• to hide/show the footer I added buttons to the header and footer that fire the GridView.RowCommand (note, the Insert also uses this technique)

Public Class MyGridView
      Inherits GridView

      Protected Overloads Overrides Function CreateChildControls(ByVal dataSource As System.Collections.IEnumerable, ByVal dataBinding As Boolean) As Integer
          Dim numRows As Integer = MyBase.CreateChildControls(dataSource, dataBinding)

          'no data rows created, create empty table if enabled
          If numRows = 0 AndAlso ShowWhenEmpty Then
              'create table
              Dim table As New Table()
              table.ID = Me.ID

              'convert the exisiting columns into an array and initialize
              Dim fields As DataControlField() = New DataControlField(Me.Columns.Count - 1) {}
              Me.Columns.CopyTo(fields, 0)

              If Me.ShowHeader Then
                  'create a new header row
                  Dim headerRow As GridViewRow = MyBase.CreateRow(-1, -1, DataControlRowType.Header, DataControlRowState.Normal)

                  Me.InitializeRow(headerRow, fields)
                  table.Rows.Add(headerRow)
              End If

              'create the empty row
              Dim emptyRow As New GridViewRow(-1, -1, DataControlRowType.EmptyDataRow, DataControlRowState.Normal)

              Dim cell As New TableCell()
              cell.ColumnSpan = Me.Columns.Count
              cell.Width = Unit.Percentage(100)
              If Not [String].IsNullOrEmpty(EmptyDataText) Then
                  cell.Controls.Add(New LiteralControl(EmptyDataText))
              End If

              If Me.EmptyDataTemplate IsNot Nothing Then
                  EmptyDataTemplate.InstantiateIn(cell)
              End If

              emptyRow.Cells.Add(cell)
              table.Rows.Add(emptyRow)

              If Me.ShowFooter Then
                  'create footer row
                  'Dim footerRow As GridViewRow = MyBase.CreateRow(-1, -1, DataControlRowType.Footer, DataControlRowState.Normal)
                  _footerRow = MyBase.CreateRow(-1, -1, DataControlRowType.Footer, DataControlRowState.Normal)

                  Me.InitializeRow(footerRow, fields)
                  table.Rows.Add(footerRow)
              End If

              Me.Controls.Clear()
              Me.Controls.Add(table)
          End If

          Return numRows
      End Function


      <Category("Behaviour")> _
      <Themeable(True)> _
      <Bindable(BindableSupport.No)> _
      Public Property ShowWhenEmpty() As Boolean
          Get
              If ViewState("ShowWhenEmpty") Is Nothing Then
                  ViewState("ShowWhenEmpty") = False
              End If

              Return CBool(ViewState("ShowWhenEmpty"))
          End Get
          Set(ByVal value As Boolean)
              ViewState("ShowWhenEmpty") = value
          End Set
      End Property

      Protected _footerRow As GridViewRow = Nothing
      Public Overloads Overrides ReadOnly Property FooterRow() As GridViewRow
          Get
              Return IIf(_footerRow Is Nothing, MyBase.FooterRow, _footerRow)
          End Get
      End Property


  End Class



<asp:ValidationSummary ID="vsumDocErrors" runat="server" />
<cc1:MyGridView ID="gvwDocs" runat="server" AutoGenerateColumns="False" DataSourceID="dsDocs"
    DataKeyNames="ID" ShowWhenEmpty="true">
    <EmptyDataTemplate>
        No related data elements</EmptyDataTemplate>
    <Columns>
        <asp:TemplateField>
            <headertemplate>
                <asp:ImageButton runat="server" CommandName="Add" AlternateText="Add New Item" ImageUrl="../images/add.png" 
                OnPreRender="AddButton_PreRender"/>
            </headertemplate>
            <itemtemplate>
                <asp:ImageButton runat="server" CommandName="Select" AlternateText="View Item" ImageUrl="../images/MGlass.png" />
                <asp:ImageButton ID="btnDelDoc" runat="server" CommandName="Delete" AlternateText="Delete Item"
                    ImageUrl="../images/cross.png"
                    visible="<%# (UserCanEdit) AndAlso (gvwDocs.ShowFooter = False) %>"
                    OnClientClick='<%#  DataBinder.Eval(Container.DataItem, "Description", "return confirm(""Are you sure you want to delete document: [{0}] ?"");")  %>' />
            </itemtemplate>
            <footertemplate>
                <asp:ImageButton ID="btnFooterCancel" runat="server" CommandName="CancelAdd" AlternateText="Cancel Add" CausesValidation="false" 
                    ImageUrl="../images/Cancel.png" 
                    OnClientClick="doCheck = false;" />
                <asp:ImageButton ID="ImageButton1" runat="server" CommandName="Insert" CommandArguement="Insert" AlternateText="Save Item"
                    ImageUrl="../images/disk.png"
                    OnClientClick="doCheck = false;" />
            </footertemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="Document Name">
            <itemtemplate>
                <asp:Label runat="server" Text='<%# CType(Container.DataItem, MyProj.Lib.Document).Description %>'></asp:Label>
            </itemtemplate>
            <footertemplate>
                <div><asp:Label runat="server" AssociatedControlID="inDocument" CssClass="Label" Style="width:120px">Select File</asp:Label>
                <asp:RequiredFieldValidator runat="server" Display="Dynamic" ErrorMessage="File has not been selected" controlToValidate="inDocument">*</asp:RequiredFieldValidator></div>
                <asp:FileUpload runat="server" id="inDocument" Style="width:500px;font-size:x-small;" />
                <asp:RegularExpressionValidator id="vldDocument" runat="server" OnLoad="Setup_Doc_Validator" ControlToValidate="inDocument" />
                <div><asp:Label runat="server" AssociatedControlID="inDocName" CssClass="Label" Style="width:120px">Friendly Name</asp:Label>
                <asp:TextBox runat="server" id="inDocName" Columns="40" Style="font-size:x-small" />(optional)</div>
                
            </footertemplate>
        </asp:TemplateField>
        <asp:BoundField DataField="CreatedBy" HeaderText="Created By" />
    </Columns>
</cc1:MyGridView>
<asp:ObjectDataSource ID="dsDocs" runat="server" SelectMethod="GetDocumentsByAgency"
    TypeName="MyProj.Lib.DocumentDAL" DeleteMethod="Delete" DataObjectTypeName="MyProj.Lib.Document">
    <SelectParameters>
        <asp:QueryStringParameter Name="intAgencyID" QueryStringField="PID" Type="Int32" />
    </SelectParameters>
</asp:ObjectDataSource>