A Guide to Optimistic Locking | Engine Yard Blog

Great post explaining how to implement optimistic locking with ActiveRecord.

While this behavior is helpful, it doesn’t solve a more worrisome problem. Let’s say Billy comes to change that same vacation destination. He opens up the edit form, bangs away at the content and walks away to get some coffee. He gets distracted and doesn’t come back to work on it for a few hours. While he’s away, Jenny makes a quick change to the destination. He comes back and finishes the content changes and submits the edit form. What happens? Well, with optimistic locking out of the box, his changes succeed and go through to the database. This is problematic for me, and is not what I would expect. This happens because the lock_version is set from the database when you instantiate the model object inside the update action. What we need is the model to be locked for Billy to the version he has when he accesses the edit form. The best way to accomplish this is by adding a...

Full article: http://www.engineyard.com/blog/2011/a-guide-to-optimistic...