LoadPostData and RaisePostDataChanged methods are part of
IPostBackDataHandler interface. That means generally controls that handle
postback data and change their state based on posted data. Such controls are
TextBox or DropDownList for example.
The working with IPostBackDataHandler is that posted data is accessed in
LoadPostData and if control state is detected to be changed based on this
process the LoadPostData returns boolean value true, otherwise false. If it
returns true, IPostBackDataHandler's RaisePostDataChanged method is called.
This method is intended to raise postback events that inform about the
change in control's state (like TextBox's TextChanged or DDL's
SelectedIndexChanged events are). Control that wants to to raise events to
signal changes in it's state must do it in RaisePostdataChanged. Reason is
that while LoadPostData is called and if you raise events there, all
controls on the Page have not yet been loaded and they are not able to
handle the changed events. LoadPostData happens before Page_Load (for
controls already in the control tree and right after Page_Load for
dynamicallya dded controls)
The RaisePostBackEvent you talked about is relevant with
IPostBackEventHandler interface. This interface allows server control to map
a client-side event into a corresponding server-side event. Such control is
Button for example . RaisePostBackEvent method is meant to raise an postback
event, with Button it is Click event for example, or with some controls it
could be multiple events based on parameters passed to the
RaisePostBackEvent.
So difference between RaisePostDataChangedEvent and RaisePostBackEvent is
the context where they are used. Both do raise postback events, but the
other does it based on change in control's state(data on postback while the
other informs there has happened some user action that caused control to
cause postback and to raise an event. Like with Button's Click event is
informed that button was clicked.
Hope this helps.
--
Teemu Keiski
MCP, Designer/Developer
Mansoft tietotekniikka Oy
http://www.mansoft.fi
AspInsiders Member,
www.aspinsiders.com
ASP.NET Forums Moderator,
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