Module: ActiveRecord::Reflection::ClassMethods
- Defined in:
- lib/active_record/reflection.rb
Overview
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.
Instance Method Summary collapse
- #create_reflection(macro, name, options, active_record) ⇒ Object
-
#reflect_on_aggregation(aggregation) ⇒ Object
Returns the AggregateReflection object for the named
aggregation
(use the symbol). -
#reflect_on_all_aggregations ⇒ Object
Returns an array of AggregateReflection objects for all the aggregations in the class.
-
#reflect_on_all_associations(macro = nil) ⇒ Object
Returns an array of AssociationReflection objects for all the aggregations in the class.
-
#reflect_on_association(association) ⇒ Object
Returns the AssociationReflection object for the named
aggregation
(use the symbol). - #reflections ⇒ Object
Instance Method Details
#create_reflection(macro, name, options, active_record) ⇒ Object
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# File 'lib/active_record/reflection.rb', line 13 def create_reflection(macro, name, , active_record) case macro when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many reflection = AssociationReflection.new(macro, name, , active_record) when :composed_of reflection = AggregateReflection.new(macro, name, , active_record) end write_inheritable_hash :reflections, name => reflection reflection end |
#reflect_on_aggregation(aggregation) ⇒ Object
Returns the AggregateReflection object for the named aggregation
(use the symbol). Example:
Account.reflect_on_aggregation(:balance) # returns the balance AggregateReflection
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# File 'lib/active_record/reflection.rb', line 35 def reflect_on_aggregation(aggregation) reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil end |
#reflect_on_all_aggregations ⇒ Object
Returns an array of AggregateReflection objects for all the aggregations in the class.
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# File 'lib/active_record/reflection.rb', line 29 def reflect_on_all_aggregations reflections.values.select { |reflection| reflection.is_a?(AggregateReflection) } end |
#reflect_on_all_associations(macro = nil) ⇒ Object
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
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# File 'lib/active_record/reflection.rb', line 43 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) ⇒ Object
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
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# File 'lib/active_record/reflection.rb', line 51 def reflect_on_association(association) reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil end |
#reflections ⇒ Object
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# File 'lib/active_record/reflection.rb', line 24 def reflections read_inheritable_attribute(:reflections) or write_inheritable_attribute(:reflections, {}) end |