Substitution control

Posted Date: 04 Nov 2009	Resource Type: Code Snippets	Category: ASP.NET WebForms
Author: krishnavenikaladi	Member Level: Gold
Rating:	Points: 5

Description :

It is used to display dynamic content on cached webpage.

Basic requirements of using Substitution Control:

The control requires input as static method with HTTPCONTEXT as parameter and should return String.

Step 1:
Create a database table:


Create table news (msg varchar(50));

Populate it with data.

Step 2:
Degign a web form with a label and substitution control.
Set the method name of substitution control to the method name.
Method code:
It should be coded under public static string (Http Context c)


//defining connection object
OracleConnection cn = new OracleConnection("user id=scott;password=tiger;data source=ganesh1");
//defining command object
OracleCommand cmd = new OracleCommand("select * from news", cn);
//instantiating the string object
string news = string.Empty;
//opening the connection
cn.Open();
//executing the statement(only one row is retrieved
news = cmd.ExecuteScalar().ToString();
//closing the connection
cn.Close();       
//returning string         
Return "<marquee>" + news + "</marquee>";
//code in page load    
//projecting text
Label1.Text = "cached time" + DateTime.Now.ToString();

Step 3: Set cache in the source of web page


<%@ OutputCache Duration ="10" VaryByParam ="none" %>

Step 4: Excute the web form

Step 5: Update the database

Step 6: Now execute the web form

Excited!!!!!!!!!!!now you wonder! The output is with last update message.

Explanation:
--->The above snippet develops connection with database and retrieves the data
--->If data is updated .....substitution control is used to display updated data.(using method which is static )

Responses

Author: ABitSmart 04 Nov 2009 Member Level: Diamond Points : 0

Please format your resource

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