services/api/lib/can_be_an_owner.rb

   1 # Protect referential integrity of owner_uuid columns in other tables
   2 # that can refer to the uuid column in this table.
   3
   4 module CanBeAnOwner
   5
   6   def self.included(base)
   7     # Rails' "has_many" can prevent us from destroying the owner
   8     # record when other objects refer to it.
   9     ActiveRecord::Base.connection.tables.each do |t|
  10       next if t == base.table_name
  11       next if t == 'schema_migrations'
  12       klass = t.classify.constantize
  13       next unless klass and 'owner_uuid'.in?(klass.columns.collect(&:name))
  14       base.has_many(t.to_sym,
  15                     foreign_key: :owner_uuid,
  16                     primary_key: :uuid,
  17                     dependent: :restrict)
  18     end
  19     # We need custom protection for changing an owner's primary
  20     # key. (Apart from this restriction, admins are allowed to change
  21     # UUIDs.)
  22     base.validate :restrict_uuid_change_breaking_associations
  23   end
  24
  25   protected
  26
  27   def restrict_uuid_change_breaking_associations
  28     return true if new_record? or not uuid_changed?
  29
  30     # Check for objects that have my old uuid listed as their owner.
  31     self.class.reflect_on_all_associations(:has_many).each do |assoc|
  32       next unless assoc.foreign_key == :owner_uuid
  33       if assoc.klass.where(owner_uuid: uuid_was).any?
  34         errors.add(:uuid,
  35                    "cannot be changed on a #{self.class} that owns objects")
  36         return false
  37       end
  38     end
  39
  40     # if I owned myself before, I'll just continue to own myself with
  41     # my new uuid.
  42     if owner_uuid == uuid_was
  43       self.owner_uuid = uuid
  44     end
  45   end
  46
  47 end