GridView inside UpdatePanel not refreshing without a call to code behind
I am new to ASP.Net and I am confused about the way a GridView control works inside an UpdatePanel.
I have read the documentation here which states "By default, any postback control inside an UpdatePanel control causes an asynchronous postback and refreshes the panel's content." yet, when I place a GridView and a Button control inside the element, unless the button has a defined OnClick event to do grid1.DataBind();, the grid will NOT refresh its data. Also, I have tried by specifying an AsyncPostBackTrigger on the UpdatePanel for the Button, but again I got the same behaviour. Now, I noticed that the UpdatePanel DOES refresh when I press a Button without OnClick event, however the GridView inside it does not. Please can you shed some light on this? Must I always have that call to code behind to explicitly refresh it?
My connection string in Web.Config
<connectionStrings>
<add name="myConnectionString"
connectionString="Data Source=XXXXX;Initial Catalog=XXXX;Persist Security Info=True;User ID=XXXXX;Password=XXXXX"
providerName="System.Data.SqlClient" />
</connectionStrings>
My Default.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="EmptyWebApp.Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server"> <title></title> </head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager" runat="server" EnablePartialRendering="true" />
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<asp:GridView ID="grid1" runat="server" DataSourceID="SQLDevelopment" AutoGenerateColumns="False">
<Columns>
<asp:BoundField DataField="UserID" HeaderText="UserID" SortExpression="UserID" />
<asp:BoundField DataField="Date" HeaderText="Date" SortExpression="Date" />
</Columns>
</asp:GridView>
<asp:SqlDataSource ID="SQLDevelopment" runat="server"
ConnectionString="<%$ ConnectionStrings:myConnectionString %>"
SelectCommand="SELECT * FROM [TestTableA]"></asp:SqlDataSource>
<%=DateTime.Now.ToString()%> <br />
<asp:Button ID="btnRefresh" runat="server" Text="Refresh without C# event"/>
<asp:Button ID="btnRefresh1" runat="server" Text="Refresh with C# event" OnClick="btnRefresh1_Click"/>
</ContentTemplate>
</asp:UpdatePanel>
</div>
</form></body><html>
My Code behind for btnRefresh1
protected void btnRefresh1_Click(object sender, EventArgs e)
{
grid1.DataBind();
}
THANK YOU
Answer
There is nothing wrong with update-panel code - issue is that grid-view will not demand the data again from data-source on post-back. Rather, it will use view-state to load the corresponding data.
However, call to DataBind will force grid-view to get the data from data source again thereby refreshing it (or you may try disabling the view-state for grid view) - see documentation for the method - comments within example code says the same.
In case, you do not want to add DataBind call in refresh button, you can do the same in Page_Load - thereby refreshing the grid on every post-back (regardless the control that has caused it).