How to remove event handlers for a content type currently in use?

Question

Hi,
We had a SP 2007 solution that managed event handlers as described in
Brian Wilson's blog regarding event handlers. We then did a in-place upgrade to SP 2010. It so happend that we wanted to remove some of our old event handlers and this is where our problem started. We managed to delete event handlers
(SPEventReceiverDefinitions) for
Site and List by using the ui from Brian Wilsons feature "Manage Event Handlers" (ref the link above), but not anyone at all for
Content Types... It simply wouldn't be deleted
(remove was grayed out in the ui). 
We then tried to do it by code. Below is a code snippet illustrating how we tried to delete the event handlers for content types:
using (SPWeb web = properties.Feature.Parent as SPWeb)
string targetClassName = "targetClassName.";
web.AllowUnsafeUpdates = true;
// Removing Content Type event handlers
foreach (SPContentType ct in web.ContentTypes)
for (int i = ct.EventReceivers.Count - 1; i >= 0; i--)
if (ct.EventReceivers[i].Class.StartsWith(targetClassName))
ct.EventReceivers[i].Delete();
ct.Update(true);
web.Update();
The Content Types are not sealed and are
not readonly. When debugging, we can see that the
Delete() method are called on one of the Content Types we wanted to delete event handlers for. We noted that the
ct.EventReceivers.Count remains the same, before and after Delete() is called. We did not get any exceptions when running this code.
When running the code a second time and debugging again, we see that the very same Content Type still has the very same event handler attached... As in, it wasn't deleted....
We also tried to delete the event handlers through PowerShell as described
here in the post by Per Jakobsen. However, the script did not really seem to find any EventReceivers... We tried to write the
$site.AllWebs | % {$_.Lists} | % {$_.ContentTypes} | % {$_.EventReceivers} list to file, but it was empty.. We did however get a long list when writing $site.AllWebs | % {$_.Lists} | % {$_.ContentTypes} to file. We could then in
that file see the event handler references we want to remove registered to our Content Types, as we did during code debugging earlier on. So PowerShell might still be the way to go here...
So, does anyone know if there is a way to force this delete through, either by code, PowerShell or some other means? Any help regarding this matter would be very much appreciated :)

Answer 1

Hi,
For your information, there's two versions (at least) exists for each content types. One is Site Content Type - exists in Root web and another is list content type. Once you add a content type to a list, a copy of the site content type is taken and stored
in the list. If you update the site content type, it may or may not affect the list conten type. So make sure you are updating the both - site content and list content type. Once you update site content type with passing paramater true to 'ct.Update(true)',
the list content types are supposed to updated too.
Thanks,
Sohel Rana
http://ranaictiu-technicalblog.blogspot.com