Rails: How to limit number of items in has_many association (from Parent)

Question

I would like to limit the number of items in an association. I want to ensure the User doesn\'t have more than X Things. This question was asked before and the solution had th

Answer 1

So if you want a different limit for each user you can add things_limit:integer into User and do

class User
  has_many :things
  validates_each :things do |user, attr, value|
   user.errors.add attr, "too much things for user" if user.things.size > user.things_limit
  end
end

class Thing
  belongs_to :user
  validates_associated :user, :message => "You have already too much things."
end

with this code you can't update the user.things_limit to a number lower than all the things he already got, and of course it restrict the user to create things by his user.things_limit.

Application example Rails 4 :

https://github.com/senayar/user_things_limit