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.
- C
- R
Source: show
# File activerecord/lib/active_record/reflection.rb, line 24 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
Source: show
# File activerecord/lib/active_record/reflection.rb, line 46 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.
Source: show
# File activerecord/lib/active_record/reflection.rb, line 38 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
Source: show
# File activerecord/lib/active_record/reflection.rb, line 60 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.
Source: show
# File activerecord/lib/active_record/reflection.rb, line 75 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
Source: show
# File activerecord/lib/active_record/reflection.rb, line 70 def reflect_on_association(association) reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil end