Module ActiveRecord::Reflection::ClassMethods
In: activerecord/lib/active_record/reflection.rb

Reflection allows you to interrogate Active Record classes and objects about their associations and aggregations. This information can, for example, be used in a form builder that took an Active Record object and created input fields for all of the attributes depending on their type and displayed the associations to other objects.

You can find the interface for the AggregateReflection and AssociationReflection classes in the abstract MacroReflection class.

Methods

create_reflection   reflect_on_aggregation   reflect_on_all_aggregations   reflect_on_all_associations   reflect_on_association   reflections  

Public Instance methods

create_reflection(macro, name, options, active_record)

[Source]

# File activerecord/lib/active_record/reflection.rb, line 13
      def create_reflection(macro, name, options, active_record)
        case macro
          when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many
            reflection = AssociationReflection.new(macro, name, options, active_record)
          when :composed_of
            reflection = AggregateReflection.new(macro, name, options, active_record)
        end
        write_inheritable_hash :reflections, name => reflection
        reflection
      end
reflect_on_aggregation(aggregation)

Returns the AggregateReflection object for the named aggregation (use the symbol). Example: 

  Account.reflect_on_aggregation(:balance) # returns the balance AggregateReflection

[Source]

# File activerecord/lib/active_record/reflection.rb, line 43
      def reflect_on_aggregation(aggregation)
        reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil
      end
reflect_on_all_aggregations()

Returns an array of AggregateReflection objects for all the aggregations in the class.

[Source]

# File activerecord/lib/active_record/reflection.rb, line 35
      def reflect_on_all_aggregations
        reflections.values.select { |reflection| reflection.is_a?(AggregateReflection) }
      end
reflect_on_all_associations(macro = nil)

Returns an array of AssociationReflection objects for all the aggregations in the class. If you only want to reflect on a certain association type, pass in the symbol (:has_many, :has_one, :belongs_to) for that as the first parameter. Example: 

  Account.reflect_on_all_associations             # returns an array of all associations
  Account.reflect_on_all_associations(:has_many)  # returns an array of all has_many associations

[Source]

# File activerecord/lib/active_record/reflection.rb, line 54
      def reflect_on_all_associations(macro = nil)
        association_reflections = reflections.values.select { |reflection| reflection.is_a?(AssociationReflection) }
        macro ? association_reflections.select { |reflection| reflection.macro == macro } : association_reflections
      end
reflect_on_association(association)

Returns the AssociationReflection object for the named aggregation (use the symbol). Example: 

  Account.reflect_on_association(:owner) # returns the owner AssociationReflection
  Invoice.reflect_on_association(:line_items).macro  # returns :has_many

[Source]

# File activerecord/lib/active_record/reflection.rb, line 64
      def reflect_on_association(association)
        reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
      end
reflections()

Returns a hash containing all AssociationReflection objects for the current class Example: 

  Invoice.reflections
  Account.reflections

[Source]

# File activerecord/lib/active_record/reflection.rb, line 30
      def reflections
        read_inheritable_attribute(:reflections) || write_inheritable_attribute(:reflections, {})
      end

[Validate]