Updating and saving an activerecord field in Rails?

Question

There is a simple method:

def get_award(user)
  u = User.find(user).score += 10
  u.save
end

My problem is, is there a potential race condition cause a user get_award twice but get only 10 score? How to avoid it?

Answer 1

You need to get the 'user' instance, update the score and save it. In your code you're saving the class, not the instantiated object:

def get_award(user)
  u = User.find(user).score += 10
  u.save
end

Answer 2

Yes it is possible.

related questions : How do I avoid a race condition in my Rails app?

You can use two kinds of locking optimistic & pessimistic

http://guides.rubyonrails.org/active_record_querying.html See point No 10