Jeremy Yoder
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Jeremy Yoder
asked on 23 Jun 2010, 03:34 PM
I tried posting this before and got an error, so I'll try again. Please delete one of them if this ends up being a double-post...
Rebind only calls the NeedDatasource event the first time on server-side when called more than once in the same postback. Seems like a bug, but I'm wondering if it's purposeful.
What I'm doing is rebinding an empty dataset to the grid to initialize it by removing all the rows, just in case something errors out during the following DB load. If the load is successful, I want to rebind the newly loaded dataset. However, it only works if I skip the first rebind, which seems odd.
6 Answers, 1 is accepted
0
Hi Jeremy,
Could you paste your aspx and code-behind (please, use the code formatter tool of the ticket editor to make the code readable). Thanks.
Greetings,
Tsvetoslav
the Telerik team
Could you paste your aspx and code-behind (please, use the code formatter tool of the ticket editor to make the code readable). Thanks.
Greetings,
Tsvetoslav
the Telerik team
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Jeremy Yoder
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answered on 25 Jun 2010, 03:47 PM
I made a simple dummy example to show it...
| <%@ Page Language="VB" AutoEventWireup="false" CodeFile="POGrid.aspx.vb" Inherits="POGrid" %> |
| <%@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %> |
| <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> |
| <html xmlns="http://www.w3.org/1999/xhtml"> |
| <head runat="server"> |
| <title></title> |
| </head> |
| <body> |
| <form id="form1" runat="server"> |
| <asp:ScriptManager ID="ScriptManager1" runat="server"> |
| </asp:ScriptManager> |
| <div> |
| <telerik:RadGrid ID="RadGridPO" runat="server" AutoGenerateColumns="False" GridLines="None" Width="500px" > |
| <HeaderContextMenu EnableAutoScroll="True"> |
| </HeaderContextMenu> |
| <MasterTableView> |
| <CommandItemSettings ShowRefreshButton="True" /> |
| <Columns> |
| <telerik:GridBoundColumn DataField="PurchaseOrderDetailDescription" HeaderText="Detail Description" |
| UniqueName="PurchaseOrderDetailDescription"> |
| </telerik:GridBoundColumn> |
| <telerik:GridBoundColumn DataField="Catalogue" HeaderText="Catalogue" UniqueName="Catalogue"> |
| </telerik:GridBoundColumn> |
| <telerik:GridBoundColumn DataField="UnitDescription" HeaderText="Unit" UniqueName="UnitDescription"> |
| </telerik:GridBoundColumn> |
| <telerik:GridNumericColumn DataField="PurchaseOrderDetailAmount" HeaderText="Amount" |
| UniqueName="PurchaseOrderDetailAmount" DataFormatString="{0:C2}"> |
| </telerik:GridNumericColumn> |
| <telerik:GridNumericColumn DataField="PurchaseOrderDetailKey" HeaderText="PurchaseOrderDetailKey" |
| UniqueName="PurchaseOrderDetailKey" Visible="False" ReadOnly="True"> |
| </telerik:GridNumericColumn> |
| </Columns> |
| </MasterTableView> |
| </telerik:RadGrid> |
| <br /> |
| <asp:Button ID="btnTwo" runat="server" Text="Two Rebinds" /> |
| <asp:Button ID="btnOne" runat="server" Text="One Rebind" /> |
| </div> |
| </form> |
| </body> |
| </html> |
| Option Strict On |
| Option Explicit On |
| Imports System.Data |
| Imports Telerik.Web.UI |
| Imports System.Web.Services |
| Partial Class POGrid |
| Inherits System.Web.UI.Page |
| Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load |
| If Not IsPostBack Then |
| If POGridData Is Nothing Then |
| Dim dt As New DataTable("PODetails") |
| dt.Columns.Add("PurchaseOrderDetailDescription", GetType(String)) |
| dt.Columns.Add("Catalogue", GetType(String)) |
| dt.Columns.Add("UnitDescription", GetType(String)) |
| dt.Columns.Add("PurchaseOrderDetailAmount", GetType(Decimal)) |
| dt.Columns.Add("PurchaseOrderDetailKey", GetType(Integer)) |
| ' Create dummy rows to delete/edit/insert |
| Dim vals(1) As String |
| vals = New String() {"Bob", "Barker", "Each", "30", "1"} |
| dt.Rows.Add(vals) |
| vals = New String() {"Harry", "Potter", "Each", "60", "2"} |
| dt.Rows.Add(vals) |
| vals = New String() {"Rudyard", "Kipling", "Each", "90", "3"} |
| dt.Rows.Add(vals) |
| vals = New String() {"Neil", "Gaiman", "Each", "120", "4"} |
| dt.Rows.Add(vals) |
| vals = New String() {"Ann", "Landers", "Each", "150", "5"} |
| dt.Rows.Add(vals) |
| HoldData = dt |
| ' Create an empty dataset to assign later. |
| Dim dtEmpty As New DataTable("Empty") |
| dtEmpty.Columns.Add("PurchaseOrderDetailDescription", GetType(String)) |
| dtEmpty.Columns.Add("Catalogue", GetType(String)) |
| dtEmpty.Columns.Add("UnitDescription", GetType(String)) |
| dtEmpty.Columns.Add("PurchaseOrderDetailAmount", GetType(Decimal)) |
| dtEmpty.Columns.Add("PurchaseOrderDetailKey", GetType(Integer)) |
| EmptyData = dtEmpty |
| POGridData = HoldData |
| End If |
| End If |
| End Sub |
| Private Sub RadGridPO_NeedDataSource(ByVal source As System.Object, ByVal e As Telerik.Web.UI.GridNeedDataSourceEventArgs) Handles RadGridPO.NeedDataSource |
| RadGridPO.DataSource = POGridData |
| End Sub |
| Private Property POGridData() As DataTable |
| Get |
| If Session("POGridData") Is Nothing Then Return Nothing |
| Return CType(Session("POGridData"), DataTable) |
| End Get |
| Set(ByVal value As DataTable) |
| Session("POGridData") = value |
| End Set |
| End Property |
| Private Property HoldData() As DataTable |
| Get |
| If Session("HoldData") Is Nothing Then Return Nothing |
| Return CType(Session("HoldData"), DataTable) |
| End Get |
| Set(ByVal value As DataTable) |
| Session("HoldData") = value |
| End Set |
| End Property |
| Private Property EmptyData() As DataTable |
| Get |
| If Session("EmptyData") Is Nothing Then Return Nothing |
| Return CType(Session("EmptyData"), DataTable) |
| End Get |
| Set(ByVal value As DataTable) |
| Session("EmptyData") = value |
| End Set |
| End Property |
| Protected Sub btnTwo_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnTwo.Click |
| POGridData = EmptyData |
| RadGridPO.Rebind() |
| POGridData = HoldData |
| RadGridPO.Rebind() |
| End Sub |
| Protected Sub btnOne_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnOne.Click |
| POGridData = EmptyData |
| POGridData = HoldData |
| RadGridPO.Rebind() |
| End Sub |
| End Class |
After clicking btnTwo, the grid still has the EmptyData because the second rebind doesn't call the NeedDataSource event.
0
Hello Jeremy,
You have forgot to attach the click handlers to the two buttons and they are just making a post-back without executing the code within them (note that AutoEventWireup="false" for your page).
Regards,
Tsvetoslav
the Telerik team
You have forgot to attach the click handlers to the two buttons and they are just making a post-back without executing the code within them (note that AutoEventWireup="false" for your page).
Regards,
Tsvetoslav
the Telerik team
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking system and vote to affect the priority of the items
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Jeremy Yoder
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answered on 06 Jul 2010, 06:57 PM
I was gone for a week and am only now able to respond.
Actually, the code executes fine -- I can put breakpoints in both button event clicks and step through them. So the problem still remains -- why does the grid remain empty after the code that rebinds twice, but not in the rebind once code?
0
Accepted
Hello Jeremy,
You should call the Rebind method just once, there is no need whatsoever to set the grid first to an empty data source and after that to the actual one.
Best wishes,
Tsvetoslav
the Telerik team
You should call the Rebind method just once, there is no need whatsoever to set the grid first to an empty data source and after that to the actual one.
Best wishes,
Tsvetoslav
the Telerik team
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Public Issue Tracking system and vote to affect the priority of the items
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Jeremy Yoder
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answered on 09 Jul 2010, 02:35 PM
Well, I wanted to to blank out the grid before trying to populate it in case the latter has an error. But with some try-catch statements and restructuring, I can make it work with only a final rebind. Good to know that rebind only works once on a postback, which I hadn't realized or read anywhere. Thanks.