ruby on rails - Limiting the number of embedded documents in Mongoid -


what correct method of limiting number of embedded documents using mongoid rails.

i've tried this:

class league   include mongoid::document    embeds_many :teams   validate :validate_teams    def validate_teams     if teams.size > 6       errors.add(:base, "too many teams")     end     if !errors.empty?       raise mongoid::errors::validations.new(self)     end   end  end

but break it:

# league 5 teams. league = league.first  # copy of league. copy = league.first  # create new team first instance of league , save. league.teams.build league.save  # create new team second instance , save. copy.teams.build copy.save  league.reload.teams.size # => 7

this case can become apparent in production multiple instances of rails app running , responding requests concurrently. need rock-solid method limit number of embedded documents. correct way this?

i ended solving using optimistic locking. there no other way definitively limit number of embedded documents.

i implemented own version of optimistic locking, here gem might useful: https://github.com/burgalon/mongoid_optimistic_locking


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