create if doesn't exist function in ActiveRecord?

Question

I'm using Rails 3.2.8. I need to create a status record if a status record doesn't already exist. If a status record exists, I don't do anything. So my code is something like this:

user_level_status = UserLevelStatus.where(user_id: user_id, level_id: level_id).first
if !user_level_status
  UserLevelStatus.create(user_id: user_id, level_id: level_id, status: UserLevelStatus::READY)
end

Is there a better way to handle this in Rails/ActiveRecord? Is there an equivalent mechanism as find_or_create_by_ ? Can I use find_or_create_by_user_id and also check for level_id ? I would just be discarding the results so even that's not so elegant.

Answer 1

Yes there is.

Rails 3

user_level_status = UserLevelStatus.find_or_create_by_user_id_and_level_id(user_id, level_id)

Rails 4:

user_level_status = UserLevelStatus.find_or_create_by(user_id: user_id, level_id: level_id)

And you should set the default status in your model .

Answer 2

你应该用

UserLevelStatus.where(user_id: user_id, level_id: level_id).first_or_create(status: UserLevelStatus::READY)

Answer 3

Use find_or_create_*

hash = {user_id: user_id, level_id: level_id, status: UserLevelStatus::READY}
UserLevelStatus.find_or_create_by_user_id_and_level_id_and_status(hash)

EDITED For your case you should use following

hash = {user_id: user_id, level_id: level_id}
UserLevelStatus.find(:first, :conditions => hash) || UserLevelStatus.create(hash.merge({status: UserLevelStatus::READY}) 

Answer 4

Another alternative is

UserLevelStatus.where(user_id: user_id, level_id: level_id).first ||
  UserLevelStatus.create(user_id: user_id, level_id: level_id, status: UserLevelStatus::READY)