For example, if you define an instance level variable in the class to store data in the As per the first look of Developers, we say simply, Item Updating and Item Updated events are fire twice when we adding a document to a document library that has the Require Check Out option enabled.This is not either issue with Share Point or issue with Custom Code.So the net result of this is that the document is uploaded and the Item Adding and Item Added events have fired, which is pretty much what you would expect.Next, let’s look at what happens when the user adds a document when the Require Check Out option is enabled.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.Share Point reads these values from the event parameter and modifies the item accordingly when the actual operation runs (e.g.If you find yourself in this situation, then you’ll have to solve the problem in code.
But that option exists to be used, and some people really do need it.
To prevent users from changing the name of the planet, you can develop a Item Updating event receiver.
This event occurs before the data is saved to the Share Point list.
One major thing you should know about the SPItem Event Receiver class is that while you can implement multiple list item event handlers in a single class, Share Point instantiates a new instance of that class for each individual event it needs to handle.
What this means is that you cannot store data in instance-level variables and share that data between event handlers.