Being one of the Sr. Developers on a project, and being responsible for Code Review and a part of the Configuration Management team I recommended we use some versioning of our assemblies. I stand by this decision on the versioning as I do believe it is very important, but when had to start modifying code in the Account Registration process I realized a flaw. I was using a SPItemEventReceiver and had not accounted for the assembly numbers changing which would affect SharePoint’s ability to call the correct event receiver. The key issue was I HAD to update the event receiver and without the ability to remove the old event handlers and replace them with the new assembly event receivers I couldn’t comply with the Code Review standards for Assembly Versioning.
After a little thinking and research the code below allowed me to resolve the issue.
Step 1. Finding and remove the old event receiver
list = spWeb.GetListFromUrl(listUrl);
bool allItemsChecked = false;
while (!allItemsChecked)
{
allItemsChecked = true;
foreach (SPEventReceiverDefinition receiver in list.EventReceivers)
{
if (
| (receiver.Type == SPEventReceiverType.ItemAdded |
receiver.Type == SPEventReceiverType.ItemUpdated)
&& receiver.Class == typeof(MyRequestItemEventReceiver).ToString()
)
{
receiver.Delete();
allItemsChecked = false;
break;
}
}
You will notice that I loop through the event receivers and each time I removed/delete a receiver I start looping again. This restart ensures that when you delete the object the foreach loop continues to work properly and does not reference deleted items. I chose to compare just the Receiver.Class because, as I mentioned above the version numbers change but the list is maintained.
I initially assumed that receiver.Type would return to me the Object.Type information. This was not an accurate assumption and I do think it is a BAD thing that Microsoft allowed in this case. Given that Type is a specific object in .NET I really think this attribute should have been named EventType, but I wasn’t asked…so… Anyway, I check the Type to ensure that I only remove the events that I added custom actions for.
Step 2. Add new event receivers
list.EventReceivers.Add(SPEventReceiverType.ItemUpdated,
this.GetType().Assembly.ToString(),
typeof(MyRequestItemEventReceiver).ToString());
list.EventReceivers.Add(SPEventReceiverType.ItemAdded,
this.GetType().Assembly.ToString(),
typeof(MyRequestItemEventReceiver).ToString());
I implemented this code as part of my SPFeatureReceiver in the FeatureActivated function, because during that event I also update some other critical items the SPItemEventReceiver uses. You may find that removing and adding your custom event receivers to the list during the FeatureActivated event is more appropriate.