Class: DataMapper::Property::Discriminator

Inherits:
Class show all
Includes:
PassThroughLoadDump
Defined in:
lib/dm-core/property/discriminator.rb

Constant Summary

Constants inherited from DataMapper::Property

INVALID_NAMES, OPTIONS, PRIMITIVES, VISIBILITY_OPTIONS

Instance Attribute Summary

Attributes inherited from DataMapper::Property

#allow_blank, #allow_nil, #default, #index, #instance_variable_name, #model, #name, #options, #primitive, #reader_visibility, #repository_name, #required, #unique_index, #writer_visibility

Instance Method Summary collapse

Methods included from PassThroughLoadDump

#dump, #load

Methods inherited from Class

#typecast_to_primitive

Methods inherited from Object

#dump, #load, #to_child_key

Methods inherited from DataMapper::Property

accept_options, accepted_options, #allow_blank?, #allow_nil?, #assert_valid_options, demodulized_names, descendants, determine_class, #determine_visibility, #field, find_class, #get, #get!, inherited, #initialize, #inspect, #key?, #lazy?, #lazy_load, #lazy_load_properties, #loaded?, nullable, options, #primitive?, #properties, #required?, #serial?, #set, #set!, #typecast, #unique?, #valid?

Methods included from Chainable

#chainable, #extendable

Methods included from Equalizer

#equalize

Methods included from Deprecate

#deprecate

Methods included from Subject

#default?, #default_for

Methods included from Assertions

#assert_kind_of

Constructor Details

This class inherits a constructor from DataMapper::Property

Instance Method Details

#bind ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future. 



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# File 'lib/dm-core/property/discriminator.rb', line 10

def bind
  model.default_scope(repository_name).update(name => model.descendants.dup << model)

  model.class_eval <<-RUBY, __FILE__, __LINE__ + 1
    extend Chainable

    extendable do
      def inherited(model)
        super  # setup self.descendants
        set_discriminator_scope_for(model)
      end

      def new(*args, &block)
        if args.size == 1 && args.first.kind_of?(Hash)
          discriminator = properties(repository_name).discriminator

          if discriminator_value = args.first[discriminator.name]
            model = discriminator.typecast_to_primitive(discriminator_value)

            if model.kind_of?(Model) && !model.equal?(self)
              return model.new(*args, &block)
            end
          end
        end

        super
      end

      private

      def set_discriminator_scope_for(model)
        model.default_scope(#{repository_name.inspect}).update(#{name.inspect} => model.descendants.dup << model)
      end
    end
  RUBY
end