Control.OnLoad Method
Assembly: System.Web (in system.web.dll)
This method notifies the server control that it should perform actions common to each HTTP request for the page it is associated with, such as setting up a database query. At this stage in the page lifecycle, server controls in the hierarchy are created and initialized, view state is restored, and form controls reflect client-side data.
Use the IsPostBack property to determine whether the page is being loaded in response to a client postback, or if it is being loaded and accessed for the first time.
The following example creates a text stream object, myFile, and uses it to print messages to a text file when defined Page and control lifecycle events occur during request processing. During the OnLoad method call, the string "Custom control has loaded" is written to the file and the text stream object is closed.
// Create a StreamWriter to write data to a text file.
TextWriter myFile = File.CreateText("c:\\NewTextFile.txt");
void Page_Load(Object sender,EventArgs e)
{
// Write status to file.
myFile.WriteLine("Page has loaded.");
} //Page_Load
void CustomControl_OnLoad(Object sender,EventArgs e)
{
myFile.WriteLine("Custom control has loaded.");
} //CustomControl_OnLoad
void CustomControl_OnUnload(Object sender,EventArgs e)
{
// Server controls final cleanup such as;
// closing files goes here
myFile.WriteLine("Custom control was unloaded.");
// Close the stream object.
myFile.Close();
} //CustomControl_OnUnload