Webform: IsPostBack property and form submit

Question

when we work with asp.net webform and when we click on submit button then postback occur. so i like to know how IsPostBack becomes true when form submit to server. who does this and how. if anyone knows the full story then please share the info with me. thanks

Saravanan V · Answer

In general an asp.net page goes through different page life-cycle stages as part of the page processing. These stages are Page request Start Initialization etc. As per Microsoft it is in this  Start  stage the page determines whether the request is a postback or a new request and sets the IsPostBack property . You can read the below MSDN article for further reference: https://msdn.microsoft.com/en-us/library/ms178472.aspx Hope this helps you. In addition I just want to share the below information. Page.RaisePostBackEvent Method notifies the server control that caused the postback that it should handle an incoming postback event. The Page object calls the RaisePostBackEvent method when a postback occurs. This call occurs in the page life cycle after loading and change notification are complete but before prerendering occurs. Useful links: Detailed information about Page object Model https://msdn.microsoft.com/en-us/library/aa479007.aspx Processing Postback Data https://msdn.microsoft.com/en-us/library/aa720471(v=vs.71).aspx https://msdn.microsoft.com/en-us/library/system.web.ui.ipostbackeventhandler.raisepostbackevent(v=vs.90).aspx Please mark the answer as accepted if it fulfills your question.

Sakthivel Ganesan · Answer

ASP .Net is responsible for updating IsPostBack property to true/false. IsPostBack is the property of Page control. So when you request a page from the server first time IsPostBack will be false. When you push the data to server using the same page ASP .Net will set the IsPostBack property to True. Hope I answered your question.

tri_inn · Answer

@Sundar you probably do not understand my question. i asked how IsPostBack get true value who does it and how..........i need some internal knowledge of asp.net

Sundar · Answer

Then keep if (! IsPostback) in load event

tri_inn · Answer

i like to know how IsPostBack property gets true when form submit ?

Sundar · Answer

IsPostBack returns true if the page is reloading. The if(IsPostBack == false) statement is saying If this is the first time the page loads do this stuff.