How to keep DataTable persistent? - asp.net

Question

I have a Gridview filled by a dataTable, filled by a DataAdapter. That's how grid is initially loaded in Page_Load.
To add a search funcionality, I make the same but passing TextBox.Text as parameter to the SELECT... LIKE ... statement.
To add an edit funcionality(a button in every row) I need the previous data in the dataTable, and if I performed a search before editing I need only the result of the search in my dataTable.
The problem is, I don't know how to keep its value alive (persistent), and dataTable has 0 columns when I press teh edit button, so it doesn't display anything to edit.
I guess it happens because I'm using Using, and dataTable is probably getting cleaned after End Using.
In that case, whta can I do to fix it? I thought removing miconn.Close() but it doesn't solve anything, in fact, I don't know if connection is still open after End Using.
Code:
Dim con As New Connection
Dim table As New DataTable()
Private Sub fill_grid()
Using miconn As New SqlConnection(con.GetConnectionString())
Dim sql As String = "SELECT area,lider_usuario FROM AREA"
Using command As New SqlCommand(sql, miconn)
Using ad As New SqlDataAdapter(command)
ad.Fill(table)
GridView1.DataSource = table
GridView1.DataBind()
'miconn.Close()
End Using
End Using
End Using
End Sub
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If Not IsPostBack Then
fill_grid()
End If
End Sub
Protected Sub btnSearch_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnSearch.Click
Dim miCon As New Connection
Using miconn As New SqlConnection(miCon.GetConnectionString())
Dim sql As String = "SELECT area,lider_usuario FROM AREA WHERE area LIKE #area"
Using command As New SqlCommand(sql, miconn)
command.Parameters.Clear()
command.Parameters.Add("#area", SqlDbType.VarChar).Value = "%" + TextBox1.Text + "%"
Using ad As New SqlDataAdapter(command)
ad.Fill(table)
GridView1.DataSource = table
GridView1.DataBind()
'miconn.Close()
End Using
End Using
End Using
End Sub
Protected Sub EditRow(ByVal sender As Object, ByVal e As GridViewEditEventArgs)
GridView1.EditIndex = e.NewEditIndex
GridView1.DataSource = table
GridView1.DataBind()
End Sub
Protected Sub CancelEditRow(ByVal sender As Object, ByVal e As GridViewCancelEditEventArgs)
GridView1.EditIndex = -1
GridView1.DataSource = table
GridView1.DataBind()
End Sub

Answer 1

BindGrid()
{
var dt = YourMethodReturningDatatable();
ViewState["Table"] = dt;
grid.DataSource = ViewState["Table"];
grid.Databind();
}
page_load
{
if(not ispostback) // not because my 1 key stopped working.
{
BindGrid();
}
}

Answer 2

I would suggest you to make two different functions for filling the data table and binding it. Call the filling function before the !IsPostBack condition and do the binding inside the condition. Here is the sample code:
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Dim table as new DataTable
table = GetData() 'The function that would return a data table
If Not IsPostBack Then
GridView1.DataSource = table
GridView1.DataBind()
End If
End Sub
Private Function GetData() As DataTable
Using miconn As New SqlConnection(con.GetConnectionString())
Dim sql As String = "SELECT area,lider_usuario FROM AREA"
Using command As New SqlCommand(sql, miconn)
Using ad As New SqlDataAdapter(command)
ad.Fill(table)
GetData = table
miconn.Close()
End Using
End Using
End Using
End function
Hope it helps.