Introduction
Here I will explain what is cross page posting in asp.net or Cross Page Postback in asp.net
using C# and VB.NET.
Description
In previous articles I explained Send values from one page to another page using QueryString,
Joins in SQL Server, Highlight Gridview records based on search and many
articles relating to Gridview,
SQL, jQuery, asp.net,
C#, VB.NET.
Now I will explain what is cross page postback in asp.net and how to use cross
page postback concept in asp.net.
Cross
Page Postback
Cross page postback is the concept which is used to
submit one page (Default.aspx) controls to another page (Default2.aspx) and
access those page (Default.aspx) control values in another page (Default2.aspx).
Here I will explain this concept with simple example
for that first create one web application and add two new pages Default.aspx and Default2.aspx.
Now open Default.aspx
page and write the following code
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Cross Page Postback
Example in asp.net</title>
</head>
<body>
<form id="form1"
runat="server">
<div>
<table>
<tr>
<td><b>Enter UserName:</b></td>
<td><asp:TextBox ID="txtUserName"
runat="server"/></td>
</tr>
<tr>
<td><b>Enter Location:</b></td>
<td><asp:TextBox ID="txtLocation"
runat="server"/></td>
</tr>
<tr>
<td></td>
<td><asp:Button ID="btnPostback"
Text="Postback"
runat="server"
PostBackUrl="~/Default2.aspx"
/> </td>
</tr>
</table>
</div>
</form>
</body>
</html>
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If you observe button control code I added property PostBackUrl="~/Default2.aspx" by using this property we will submit Default.aspx page
control values to Default2.aspx page.
Now open Default2.aspx
page and write the following code
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Cross Page Postback
Example in asp.net</title>
</head>
<body>
<form id="form1"
runat="server">
<div>
<b><u>Default2.aspx Page</u></b><br /><br />
<label id="lblName"
runat="server"
/><br
/><br
/>
<label id="lblLocation"
runat="server"
/>
</div>
</form>
</body>
</html>
|
Now open Default2.aspx
code behind file and add following namespaces
C#
Code
using System;
using
System.Web.UI.WebControls;
|
Once namespaces added write the following code
protected void Page_Load(object
sender, EventArgs e)
{
if (PreviousPage != null
&& PreviousPage.IsCrossPagePostBack)
{
TextBox txtName =
(TextBox)PreviousPage.FindControl("txtUserName");
TextBox
txtLocation = (TextBox)PreviousPage.FindControl("txtLocation");
lblName.InnerText = "Welcome to
Default2.aspx page " + txtName.Text;
lblLocation.InnerText = "Your
Location: " + txtLocation.Text;
}
else
{
Response.Redirect("Default.aspx");
}
}
|
VB.NET
Code
Imports
System.Web.UI.WebControls
Partial Class Default3
Inherits System.Web.UI.Page
Protected Sub Page_Load(sender As
Object, e As EventArgs) Handles
Me.Load
If PreviousPage IsNot
Nothing AndAlso
PreviousPage.IsCrossPagePostBack Then
Dim txtName As TextBox = DirectCast(PreviousPage.FindControl("txtUserName"), TextBox)
Dim txtLocation As TextBox = DirectCast(PreviousPage.FindControl("txtLocation"), TextBox)
lblName.InnerText = "Welcome to
Default2.aspx page " & txtName.Text
lblLocation.InnerText = "Your
Location: " & txtLocation.Text
Else
Response.Redirect("Default.aspx")
End If
End Sub
End Class
|
If you observe above codePreviousPageproperty
of current page (Default2.aspx)is NOT NULL, this is to avoid errors in
case that user opens our Default2.aspx directly, and here we checked another
property called IsCrossPagePostBack to see if we really had a
CrossPagePostback.
If
both properties Page.PreviousPage is NOT NULL and PreviousPage.IsCrossPagePostback
is true then only we can say
CrossPagePostback happen.
Demo
 |
Download
Sample Code Attached
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6 comments :
it's really nice article
i think this is more easier like,
in default2.aspx, in page_load
assign
string uname,loc;
uname=Request.form["txtUserName"];
loc=Request.form["txtLocation"];
lblName.text=string.format("Welcome to Default2.aspx page {0}
Your Location: {1}",uname,loc)
only 1 label is enough
SIR PLEASE TELL ME LIKE GMAIL SUPPOSE I AM LOGGING IN GMAIL THEN THERE IS ALSO A CROSS PAGE POSTBACK WITH SOME GIF IMAGE WHICH SHOW THE WATING ,SIR IS THIS POSSIBLE WITH THIS CODING/PLEASE ANSWER ME SIR
Valuable example it's a great article thanks for sharing this informative information.. I will visit your blog regularly for some latest post.
Awesome...!
gud