module ActiveRecord::Reflection::ClassMethods
Reflection enables to interrogate Active Record classes and objects about their associations and aggregations. This information can, for example, be used in a form builder that takes an Active Record object and creates input fields for all of the attributes depending on their type and displays the associations to other objects.
MacroReflection class has info for AggregateReflection and AssociationReflection classes.
Public Instance Methods
# File lib/active_record/reflection.rb, line 23 def create_reflection(macro, name, options, active_record) case macro when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many klass = options[:through] ? ThroughReflection : AssociationReflection reflection = klass.new(macro, name, options, active_record) when :composed_of reflection = AggregateReflection.new(macro, name, options, active_record) end self.reflections = self.reflections.merge(name => reflection) reflection end
Returns the AggregateReflection
object for the named aggregation
(use the symbol).
Account.reflect_on_aggregation(:balance) # => the balance AggregateReflection
# File lib/active_record/reflection.rb, line 45 def reflect_on_aggregation(aggregation) reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil end
Returns an array of AggregateReflection objects for all the aggregations in the class.
# File lib/active_record/reflection.rb, line 37 def reflect_on_all_aggregations reflections.values.grep(AggregateReflection) end
Returns an array of AssociationReflection objects for all
the associations in the class. If you only want to reflect on a certain
association type, pass in the symbol (:has_many
,
:has_one
, :belongs_to
) 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
# File lib/active_record/reflection.rb, line 59 def reflect_on_all_associations(macro = nil) association_reflections = reflections.values.grep(AssociationReflection) macro ? association_reflections.select { |reflection| reflection.macro == macro } : association_reflections end
Returns an array of AssociationReflection objects for all
associations which have :autosave
enabled.
# File lib/active_record/reflection.rb, line 74 def reflect_on_all_autosave_associations reflections.values.select { |reflection| reflection.options[:autosave] } end
Returns the AssociationReflection
object for the association
(use the symbol).
Account.reflect_on_association(:owner) # returns the owner AssociationReflection Invoice.reflect_on_association(:line_items).macro # returns :has_many
# File lib/active_record/reflection.rb, line 69 def reflect_on_association(association) reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil end