module ActiveRecord::Reflection::ClassMethods
Reflection enables the ability to examine the associations and aggregations of Active Record classes and objects. This information, for example, can 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
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 66 def reflect_on_aggregation(aggregation) aggregate_reflections[aggregation.to_s] end
Returns an array of AggregateReflection
objects for all the aggregations in the class.
# File lib/active_record/reflection.rb, line 58 def reflect_on_all_aggregations aggregate_reflections.values 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 103 def reflect_on_all_associations(macro = nil) association_reflections = reflections.values association_reflections.select! { |reflection| reflection.macro == macro } if macro association_reflections end
Returns an array of AssociationReflection
objects for all associations which have :autosave
enabled.
# File lib/active_record/reflection.rb, line 123 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 114 def reflect_on_association(association) reflections[association.to_s] end
Returns a Hash of name of the reflection as the key and an AssociationReflection
as the value.
Account.reflections # => {"balance" => AggregateReflection}
# File lib/active_record/reflection.rb, line 74 def reflections @__reflections ||= begin ref = {} _reflections.each do |name, reflection| parent_reflection = reflection.parent_reflection if parent_reflection parent_name = parent_reflection.name ref[parent_name.to_s] = parent_reflection else ref[name] = reflection end end ref end end