Here is a MS example in VB[1]. ASP.NET is not like windows forms or
console applications when it comes to where data is remembered between
call. In order for the server to know what data should be displayed
either session state is needed or you must specify the DataSource on all
page requests. Notice the code below calls the sub BindData() once for
each page request. With out it how does ASP.NET know what data to use?
If you are using session state try not doing the DataBind() at all, it
should remember.
HTH
Jay
[1]
<%@ Import Namespace="System.Data" %>
<%@ Import Namespace="System.Data.SqlClient" %>
<html>
<script language="VB" runat="server">
Dim MyConnection As SqlConnection
Sub Page_Load(Sender As Object, E As EventArgs)
MyConnection = New
SqlConnection("server=(local)\NetSDK;database=pubs;Trusted_Connection=ye
s")
If Not (IsPostBack)
BindGrid()
End If
End Sub
Sub MyDataGrid_Edit(Sender As Object, E As DataGridCommandEventArgs)
MyDataGrid.EditItemIndex = CInt(E.Item.ItemIndex)
BindGrid()
End Sub
Sub MyDataGrid_Cancel(Sender As Object, E As
DataGridCommandEventArgs)
MyDataGrid.EditItemIndex = -1
BindGrid()
End Sub
Sub MyDataGrid_Update(Sender As Object, E As
DataGridCommandEventArgs)
Dim DS As DataSet
Dim MyCommand As SqlCommand
Dim UpdateCmd As String = "UPDATE Authors SET au_id = @Id,
au_lname = @LName, au_fname = @FName, phone = " _
& " @Phone, address = @Address, city = @City, state =
@State, zip = @Zip, contract = @Contract where au_id = @Id"
MyCommand = New SqlCommand(UpdateCmd, MyConnection)
MyCommand.Parameters.Add(New SqlParameter("@Id",
SqlDbType.NVarChar, 11))
MyCommand.Parameters.Add(New SqlParameter("@LName",
SqlDbType.NVarChar, 40))
MyCommand.Parameters.Add(New SqlParameter("@FName",
SqlDbType.NVarChar, 20))
MyCommand.Parameters.Add(New SqlParameter("@Phone",
SqlDbType.NChar, 12))
MyCommand.Parameters.Add(New SqlParameter("@Address",
SqlDbType.NVarChar, 40))
MyCommand.Parameters.Add(New SqlParameter("@City",
SqlDbType.NVarChar, 20))
MyCommand.Parameters.Add(New SqlParameter("@State",
SqlDbType.NChar, 2))
MyCommand.Parameters.Add(New SqlParameter("@Zip",
SqlDbType.NChar, 5))
MyCommand.Parameters.Add(New SqlParameter("@Contract",
SqlDbType.NVarChar,1))
MyCommand.Parameters("@Id").Value =
MyDataGrid.DataKeys(CInt(E.Item.ItemIndex))
Dim Cols As String() =
{"@Id","@LName","@FName","@Phone","@Address","@City","@State","@Zip","@C
ontract"}
Dim NumCols As Integer = E.Item.Cells.Count
Dim I As Integer
For I=2 To NumCols-2 'skip first, second and last column
Dim CurrentTextBox As TextBox
CurrentTextBox = E.Item.Cells(I).Controls(0)
Dim ColValue As String = CurrentTextBox.Text
' Check for null values in required fields
If I<6 And ColValue = ""
Message.InnerHtml = "ERROR: Null values not allowed for
Author ID, Name or Phone"
Message.Style("color") = "red"
Return
End If
MyCommand.Parameters(Cols(I-1)).Value = ColValue
Next
' Append last row, converting true/false values to 0/1
Dim ContractTextBox As TextBox
ContractTextBox = E.Item.Cells(NumCols-1).Controls(0)
If ContractTextBox.Text = "true"
MyCommand.Parameters("@Contract").Value = "1"
Else
MyCommand.Parameters("@Contract").Value = "0"
End If
MyCommand.Connection.Open()
Try
MyCommand.ExecuteNonQuery()
Message.InnerHtml = "<b>Record Updated</b><br>" &
UpdateCmd.ToString()
MyDataGrid.EditItemIndex = -1
Catch Exp As SQLException
If Exp.Number = 2627
Message.InnerHtml = "ERROR: A record already exists with
the same primary key"
Else
Message.InnerHtml = "ERROR: Could not update record,
please ensure the fields are correctly filled out"
End If
Message.Style("color") = "red"
End Try
MyCommand.Connection.Close()
BindGrid()
End Sub
Sub BindGrid()
Dim DS As DataSet
Dim MyCommand As SqlDataAdapter
MyCommand = new SqlDataAdapter("select * from Authors",
MyConnection)
DS = new DataSet()
MyCommand.Fill(DS, "Authors")
MyDataGrid.DataSource=DS.Tables("Authors").DefaultView
MyDataGrid.DataBind()
End Sub
</script>
<body style="font: 10pt verdana">
<form runat="server">
<h3><font face="Verdana">Updating a Row of Data</font></h3>
<span id="Message" EnableViewState="false" style="font: arial 11pt;"
runat="server"/><p>
<ASP:DataGrid id="MyDataGrid" runat="server"
Width="800"
BackColor="#ccccff"
BorderColor="black"
ShowFooter="false"
CellPadding=3
CellSpacing="0"
Font-Name="Verdana"
Font-Size="8pt"
HeaderStyle-BackColor="#aaaadd"
OnEditCommand="MyDataGrid_Edit"
OnCancelCommand="MyDataGrid_Cancel"
OnUpdateCommand="MyDataGrid_Update"
DataKeyField="au_id"
>
<Columns>
<asp:EditCommandColumn EditText="Edit" CancelText="Cancel"
UpdateText="Update" ItemStyle-Wrap="false"/>
</Columns>
</ASP:DataGrid>
</form>
</body>
</html>
-----Original Message-----
From: dotnet discussion [mailto:[EMAIL PROTECTED]] On Behalf Of
Marina Zlatkina
Sent: Friday, April 12, 2002 4:13 PM
To: [EMAIL PROTECTED]
Subject: Re: [DOTNET] DataGrid
The DataGrid object is bound to a data source in the designer. But I
have
also tried explicitly setting the DataSource property again in that
event
handler, which didn't change anything.
The strange thing is, if after I get this empty DataGrid, I click the
button that gets me the data in the first place, I get the original
DataGrid, with the appropriate row in edit mode!
But that seems inherintly wrong, that I need to try to get the data
again,
before I can edit...
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