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Diffstat (limited to 'activerecord/lib/active_record/reflection.rb')
| -rw-r--r-- | activerecord/lib/active_record/reflection.rb | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb new file mode 100644 index 0000000000..036200a200 --- /dev/null +++ b/activerecord/lib/active_record/reflection.rb @@ -0,0 +1,126 @@ +module ActiveRecord + module Reflection # :nodoc: + def self.append_features(base) + super + base.extend(ClassMethods) + + base.class_eval do + class << self + alias_method :composed_of_without_reflection, :composed_of + + def composed_of_with_reflection(part_id, options = {}) + composed_of_without_reflection(part_id, options) + write_inheritable_array "aggregations", [ AggregateReflection.new(part_id, options, self) ] + end + + alias_method :composed_of, :composed_of_with_reflection + end + end + + for association_type in %w( belongs_to has_one has_many has_and_belongs_to_many ) + base.module_eval <<-"end_eval" + class << self + alias_method :#{association_type}_without_reflection, :#{association_type} + + def #{association_type}_with_reflection(association_id, options = {}) + #{association_type}_without_reflection(association_id, options) + write_inheritable_array "associations", [ AssociationReflection.new(association_id, options, self) ] + end + + alias_method :#{association_type}, :#{association_type}_with_reflection + end + end_eval + end + end + + # 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. + module ClassMethods + # Returns an array of AggregateReflection objects for all the aggregations in the class. + def reflect_on_all_aggregations + read_inheritable_attribute "aggregations" + end + + # Returns the AggregateReflection object for the named +aggregation+ (use the symbol). Example: + # Account.reflect_on_aggregation(:balance) # returns the balance AggregateReflection + def reflect_on_aggregation(aggregation) + reflect_on_all_aggregations.find { |reflection| reflection.name == aggregation } unless reflect_on_all_aggregations.nil? + end + + # Returns an array of AssociationReflection objects for all the aggregations in the class. + def reflect_on_all_associations + read_inheritable_attribute "associations" + end + + # Returns the AssociationReflection object for the named +aggregation+ (use the symbol). Example: + # Account.reflect_on_association(:owner) # returns the owner AssociationReflection + def reflect_on_association(association) + reflect_on_all_associations.find { |reflection| reflection.name == association } unless reflect_on_all_associations.nil? + end + end + + + # Abstract base class for AggregateReflection and AssociationReflection that describes the interface available for both of + # those classes. Objects of AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods. + class MacroReflection + attr_reader :active_record + def initialize(name, options, active_record) + @name, @options, @active_record = name, options, active_record + end + + # Returns the name of the macro, so it would return :balance for "composed_of :balance, :class_name => 'Money'" or + # :clients for "has_many :clients". + def name + @name + end + + # Returns the hash of options used for the macro, so it would return { :class_name => "Money" } for + # "composed_of :balance, :class_name => 'Money'" or {} for "has_many :clients". + def options + @options + end + + # Returns the class for the macro, so "composed_of :balance, :class_name => 'Money'" would return the Money class and + # "has_many :clients" would return the Client class. + def klass() end + + def ==(other_aggregation) + name == other_aggregation.name && other_aggregation.options && active_record == other_aggregation.active_record + end + end + + + # Holds all the meta-data about an aggregation as it was specified in the Active Record class. + class AggregateReflection < MacroReflection #:nodoc: + def klass + Object.const_get(options[:class_name] || name_to_class_name(name.id2name)) + end + + private + def name_to_class_name(name) + name.capitalize.gsub(/_(.)/) { |s| $1.capitalize } + end + end + + # Holds all the meta-data about an association as it was specified in the Active Record class. + class AssociationReflection < MacroReflection #:nodoc: + def klass + active_record.send(:compute_type, (name_to_class_name(name.id2name))) + end + + private + def name_to_class_name(name) + if name !~ /::/ + class_name = active_record.send( + :type_name_with_module, + (options[:class_name] || active_record.class_name(active_record.table_name_prefix + name + active_record.table_name_suffix)) + ) + end + return class_name || name + end + end + end +end
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