I have a conditional active record query that checks to see if a relationship of type X exists (.count > 0) where attribute x and attribute y match specific input or if they match when attribute x and attribute y are switched.

I currently use an || operator with two long active record queries to cover both situations.

def coach_of?(user)
  if UserRelation.where(relation_type: 'coach-student').where(user_id: self.id).where(with_user_id: user.id).count > 0 || 
     UserRelation.where(relation_type: 'coach-student').where(user_id: user.id).where(with_user_id: self.id).count > 0

Is there a more clever way to do this or is this kind of query acceptable?


Some notes:

  • if boolean then true else false end -> boolean.

  • UserRelation.where(user_id: self.id).where(with_user_id: user.id) -> UserRelation.where(user_id: self.id, with_user_id: user.id)

  • active_record_collection.count > 0 -> active_record_collection.exists?

  • I don't understand why you have to check both ways, a "coach - student" relationship looks unidirectional.

Anyway, if you set up the coach_students association, you may write something like this:

def coach_of?(user)
  coach_students.where(with_user_id: user).exists? || 
    user.coach_students.where(with_user_id: self).exists?

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