Add data to gridview, from textbox, on button click - asp.net

Question

I am working on an aspx site that lets an admin-level user fill out a form with potential member data. Once the form is filled out, the user will click submit and the data will go off to different tables. One part of the form that is stumping me involves filling out three textboxes (txtFirstName, txtLastName, txtGrade). I have a button (btnAddStudent), that, when clicked, should add the information from the textboxes to a table-like display area. I am trying to use a gridview, but there is nothing to bind it to. There is no memberID number to load a blank record from the Student table (which is a many-to-one relation to Member table). The member record is what this form is creating, and the student data will be added to the Student table when the Submit button is clicked.
I am currently working with the code found in the reply here. But when I click the "Add Student" button, I get a new blank row, but my textbox values are not inputted in the gridview.
Can this work, or do I need to look at using a table and adding rows of textboxes dynamically?
Here is relevant source code:
<tr>
<td class="style8">
<asp:Label ID="Label18" runat="server" Text="Chidren:" Font-Bold="True" Font- Underline="True" Font-Names="Tahoma"></asp:Label>
</td>
</tr>
<tr>
<td class="style8">
<asp:Label ID="Label19" runat="server" Text="First Name:"></asp:Label>
</td>
<td class="style7">
<asp:TextBox ID="txtChildFirstName" runat="server" CssClass="textbox"></asp:TextBox>
</td>
<td class="">
<asp:Label ID="Label20" runat="server" Text="Last Name:"></asp:Label>
</td>
<td class="style6">
<asp:TextBox ID="txtChildLastName" runat="server" CssClass="textbox"></asp:TextBox>
</td>
<td class="style5" align="right">
<asp:Label ID="Label21" runat="server" Text="Grade:"></asp:Label>
</td>
<td class="style4">
<asp:TextBox ID="txtGrade" runat="server" Width="52px" CssClass="textbox"></asp:TextBox>
</td>
<td>
<asp:Button ID="btnAddChild" runat="server" Text="Add Child" OnClick="btnAddChild_Click" />
</td>
</tr>
<tr>
<td valign="top" class="style8">
<asp:Label ID="Label22" runat="server" Text="Student List:"></asp:Label>
</td>
<td colspan="3">
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<ContentTemplate>
<asp:GridView ID="gvStudentList" runat="server" AutoGenerateColumns="False"
PageSize="5" Height="42px">
<AlternatingRowStyle BackColor="#E0E0E0" />
<Columns>
<asp:BoundField AccessibleHeaderText="FirstName" HeaderText="First Name" />
<asp:BoundField AccessibleHeaderText="LastName" HeaderText="Last Name" />
<asp:BoundField AccessibleHeaderText="Grade" HeaderText="Grade" />
</Columns>
<HeaderStyle BackColor="#CCCCCC" Height="25px" />
<RowStyle Height="22px" />
</asp:GridView>
</ContentTemplate>
</asp:UpdatePanel>
And the Code Behind:
'A method that will BIND the GridView based on the TextBox
'values and retain its values on post backs.
Private Sub BindGrid(rowcount As Integer)
Dim dt As New DataTable()
Dim dr As DataRow
dt.Columns.Add(New System.Data.DataColumn("FirstName", GetType([String])))
dt.Columns.Add(New System.Data.DataColumn("LastName", GetType([String])))
dt.Columns.Add(New System.Data.DataColumn("Grade", GetType([String])))
If ViewState("CurrentData") IsNot Nothing Then
For i As Integer = 0 To rowcount
dt = DirectCast(ViewState("CurrentData"), DataTable)
If dt.Rows.Count > 0 Then
dr = dt.NewRow()
dr(0) = dt.Rows(0)(0).ToString()
End If
Next
dr = dt.NewRow()
dr(0) = txtChildFirstName.Text
dr(1) = txtChildLastName.Text
dr(2) = txtGrade.Text
dt.Rows.Add(dr)
Else
dr = dt.NewRow()
dr(0) = txtChildFirstName.Text
dr(1) = txtChildLastName.Text
dr(2) = txtGrade.Text
dt.Rows.Add(dr)
End If
' If ViewState has a data then use the value as the DataSource
If ViewState("CurrentData") IsNot Nothing Then
gvStudentList.DataSource = DirectCast(ViewState("CurrentData"), DataTable)
gvStudentList.DataBind()
Else
' Bind GridView with the initial data assocaited in the DataTable
gvStudentList.DataSource = dt
gvStudentList.DataBind()
End If
' Store the DataTable in ViewState to retain the values
ViewState("CurrentData") = dt
End Sub
Protected Sub btnAddChild_Click(sender As Object, e As EventArgs) Handles btnAddChild.Click
' Check if the ViewState has a data assoiciated within it. If
If ViewState("CurrentData") IsNot Nothing Then
Dim dt As DataTable = DirectCast(ViewState("CurrentData"), DataTable)
Dim count As Integer = dt.Rows.Count
BindGrid(count)
Else
BindGrid(1)
End If
txtChildFirstName.Text = String.Empty
txtChildLastName.Text = String.Empty
txtGrade.Text = String.Empty
txtChildFirstName.Focus()
End Sub
With "BindGrid()" being called in the Page_Load event. (And yes, I have ScriptManager)

Answer 1

Try to use
Session("CurrentData") = dt on your BindGrid()
Then Create Method that just refreshes the grid after postback:
Private Sub RefreshGrid()
{
If ViewState("CurrentData") IsNot Nothing Then
gvStudentList.DataSource = DirectCast(Session("CurrentData"), DataTable)
gvStudentList.DataBind()
Else
gvStudentList.DataSource = null;
gvStudentList.DataBind()
EndIf
}
On your page load just call:
If IsPostBack Then
Return
End If
RefreshGrid()
Regards