If you catch exceptions in your own code, you can create your own error messages and cancel the operation to the list item.
This is my first post in 2013, here I just want to discuss about Event Receivers in Share Point 2010 (SPItem Event Receiver class) and an important factor with the Event Receivers.
Next, let’s look at what happens when the user adds a document when the Require Check Out option is enabled.
The first time the Item Updating and Item Updated events fire it is in response to the document properties changing.
Let me start with “What is an Item Event Receiver”Item Event receivers in Microsoft Share Point 2010 enable your custom code to respond when specific actions occur on a Share Point List Item.
Instead of writing more paragraphs I can use tabular to explain, I think this will be easy to understand.
The second time they fire it is in response to the document being checked in.
It appears as though they are firing twice in this situation because Share Point is updating the properties on the document and then checking it in on the same request.
This message is displayed on the standard Share Point error page.
The Item Updating list item event receiver is invoked when a user edits information about a course that already exists.
Each event method has a SPItem Event Properties parameter named properties.
If you wish to modify a property value on the list item during the event, the value should be updated in After Properties property of the properties parameter.
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