SharePoint Event Receivers + ItemAdded + Null Columns fun

Fri, 02 Mar 2012 18:24:06 +0000

Event receivers enable you to run some action when a particular event occurs. For example, every time a new item is added to a list, you may want to run some code, or start a workflow. This is really handy - but be aware of some gotchas. SharePoint event receivers will generally be one of two types - an “-ing” event or an “-ed” event, such as ItemAdding or ItemAdded. As their name suggests, an -ing event runs whilst the the event is happening (and might therefore give you the option to cancel it) and -ed events occur after the event has occurred. You need to be aware of how these events run. Generally, the -ing events run synchronously, that is, they are blocking and run in the same thread/cycle that they were generated in, and -ed events run asynchronously, meaning the opposite - they are not blocking - they will be run in a separate thread and not block the execution of the main thread. You therefore need to be aware of what info may, or may not, be available to you when you run code in an event receiver.

Threading on Matt Thornton

SharePoint Event Receivers + ItemAdded + Null Columns fun