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The secret of ViewStateModeById
I recently had a problem in ASP.Net
that was certain to put me in an asylum. Here is the story:
I've a page that loads controls
dynamically. On postback, the page would replace the dynamic control with a
different one. Both controls had a drop down list, each with its own ID, each
with its own values.
The problem that I had was that for
some unknown reason, the values from the first list were copied to the second
list. I had no idea what was happening, and I was one step away from finding just
how strong the walls are*.
Eventually a friend found out the
answer. Apparently ASP.Net 2.0 uses indexes instead of IDs to figure out which
view state belongs to which control. By some freak accident, I managed to stumble
on the one occasion where this would be a problem. The solution to the problem?
Just decorate the controls you're loading with ViewStateModeById,
and you're done.
One thing that I noticed is that
it's not possible to mix & match controls with this attribute and controls
without it. I get view state exception when I try to do that. It doesn't bother
me one bit, since the exception at least remind me that I need the attribute,
and that would save a bug to fix later.
* For instance, are they stronger
then my head?
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