Reflection enables interrogating of 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.
- R
Returns the AggregateReflection object for the named
aggregation
(use the symbol).
Account.reflect_on_aggregation(:balance) # => the balance AggregateReflection
Returns an array of AggregateReflection objects for all the aggregations in the class.
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
@api public
Returns an array of AssociationReflection objects for all associations
which have :autosave
enabled.
@api public
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
@api public
Returns a Hash of name of the reflection as the key and a AssociationReflection as the value.
Account.reflections # => {"balance" => AggregateReflection}
@api public
# File activerecord/lib/active_record/reflection.rb, line 70 def reflections @__reflections ||= begin ref = {} _reflections.each do |name, reflection| parent_name, parent_reflection = reflection.parent_reflection if parent_name ref[parent_name] = parent_reflection else ref[name] = reflection end end ref end end