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_with_exception)
  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   def descendant_project_uuids
  26     install_view('ancestor')
  27     ActiveRecord::Base.connection.
  28       exec_query('SELECT ancestor_view.uuid
  29                   FROM ancestor_view
  30                   LEFT JOIN groups ON groups.uuid=ancestor_view.uuid
  31                   WHERE ancestor_uuid = $1 AND groups.group_class = $2',
  32                   # "name" arg is a query label that appears in logs:
  33                   "descendant_project_uuids for #{self.uuid}",
  34                   # "binds" arg is an array of [col_id, value] for '$1' vars:
  35                   [[nil, self.uuid], [nil, 'project']],
  36                   ).rows.map do |project_uuid,|
  37       project_uuid
  38     end
  39   end
  40
  41   protected
  42
  43   def restrict_uuid_change_breaking_associations
  44     return true if new_record? or not uuid_changed?
  45
  46     # Check for objects that have my old uuid listed as their owner.
  47     self.class.reflect_on_all_associations(:has_many).each do |assoc|
  48       next unless assoc.foreign_key == :owner_uuid
  49       if assoc.klass.where(owner_uuid: uuid_was).any?
  50         errors.add(:uuid,
  51                    "cannot be changed on a #{self.class} that owns objects")
  52         return false
  53       end
  54     end
  55
  56     # if I owned myself before, I'll just continue to own myself with
  57     # my new uuid.
  58     if owner_uuid == uuid_was
  59       self.owner_uuid = uuid
  60     end
  61   end
  62
  63   def install_view(type)
  64     conn = ActiveRecord::Base.connection
  65     self.class.transaction do
  66       # Check whether the temporary view has already been created
  67       # during this connection. If not, create it.
  68       conn.exec_query "SAVEPOINT check_#{type}_view"
  69       begin
  70         conn.exec_query("SELECT 1 FROM #{type}_view LIMIT 0")
  71       rescue
  72         conn.exec_query "ROLLBACK TO SAVEPOINT check_#{type}_view"
  73         sql = File.read(Rails.root.join("lib", "create_#{type}_view.sql"))
  74         conn.exec_query(sql)
  75       ensure
  76         conn.exec_query "RELEASE SAVEPOINT check_#{type}_view"
  77       end
  78     end
  79   end
  80 end