Getting the DataKey Value in ASP.NET GridView on Button command event

Question

Gridview is configured:

 <asp:GridView ID="gvApptList" runat="server" CssClass="fullwidth" AutoGenerateColumns="False" DataKeyNames="AppointmentID">
                <Columns>
                    <asp:BoundField DataField="Designer" HeaderText="Designer" SortExpression="Designer" />
                    <asp:BoundField DataField="AppointmentDTM" HeaderText="Appointment Date" SortExpression="AppointmentDTM" DataFormatString="{0:MM-dd-yyyy hh:mm tt}" />
                    <asp:BoundField DataField="Status" HeaderText="Status" SortExpression="Status" />
                    <asp:BoundField DataField="Disposition" HeaderText="Disposition" SortExpression="Disposition" />
                    <asp:BoundField DataField="AppointmentNotes" HeaderText="Appointment Notes" SortExpression="AppointmentNotes" />
                    <asp:ButtonField ButtonType="Button" CommandName="viewAppointment" Text="View" />
                </Columns>
            </asp:GridView>

When I click the "View" button, the gvApptList_RowCommand fires off. COde for it is:

If e.CommandName = "viewAppointment" Then
        Dim tApptID As Long
        gvApptList.SelectedIndex = e.CommandArgument
        If IsNumeric(gvApptList.DataKeys(e.CommandArgument).Value) Then
            tApptID = gvApptList.SelectedDataKey.Value
        Else
            Exit Sub
        End If
        tbAppointmentID.Text = tApptID
        DisplayInfo()
    End If

The gvApptList.DataKeys(e.CommandArgument).Value always comes back as nothing. What am I missing here? I have this exact sale code working on other pages.

Answer 1

Pertinent to your task, the correct syntax using DataKeys in ASP.NET GridView control is shown below (re: http://www.codeproject.com/Tips/225352/Nesting-GridView-control-in-ASP-NET, written in C#):

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e) 
{
   if (e.Row.RowType == DataControlRowType.DataRow)
   {
     // get data key from selected row
     s.SelectParameters[0].DefaultValue =Convert.ToString(((GridView)sender).DataKeys[e.Row.RowIndex].Values["AppointmentID "]);
    }
}

You should obtain the reference to the Row corresponding to the command Button clicked, then extract the DataKeys value from that Row. Also, make sure that underlying DataSource contains AppointmentID field in its SELECT query.

Pertinent to your case it may look like the following (see Listing 2)

Listing 2.

protected void ViewButton_OnClick(object sender, EventArgs e)
{
    Button btn = sender as Button;
    GridViewRow row = btn.NamingContainer as GridViewRow;
    string strID = gvApptList.DataKeys[row.RowIndex].Values["AppointmentID"].ToString();

    int intID;
    if (String.IsNotNullOrEmpty(strID)
    {
      intID = int.Parse(strID);
    }
}

or you may use TryParse(), Convert(), etc.

Hope this may help.