Custom postback code and RegsiterForEventValidation

[Andreas Bergmeier]

Hi.
Is there some KB article how to use EnableEventValidation when doing
customized posts? Basicly we're building a post string via javascript
and issue it via means of XMLHttpRequest to the server.
This worked fine in .NET 1.1

Now in ASP.NET 2.0 I get an error message: 'Invalid postback or callback
argument. Event validation is enabled using <pages
enableEventValidation="true"/> in configuration or <%@ Page
EnableEventValidation="true" %> in a page. For security purposes, this
feature verifies that arguments to postback or callback events originate
from the server control that originally rendered them. If the data is
valid and expected, use the
ClientScriptManager.RegisterForEventValidation method in order to
register the postback or callback data for validation.'

But even after I add the RegisterForEventValidation call I still get
this error message. So I'd be interested in what one has to do to setup
ones' code for postback to the server. (I didn't yet disassemble the
asp.net code).

Regards
Andreas

 

[bruce barker]

event validation checks that only enabled and rendered (visible)
controls (status stored in viewstate) and with eventhandlers are posting
back for event handling. for controls with a know set of values (say a
drop down) asp.net also checks the value is in range. this is
implemented for several built in controls.

registerforeventvalidation allows you to add this feature to your own
custom controls. it must be called during render and once for every
legal postback value (clientid,value), once to allow clientpostback
(clientid).

you can turn this feature off at site (web config) or page level with
EnableEventValidation.

-- bruce (sqlwork.com)