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b5ba377b78
git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@3357 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
150 lines
5.8 KiB
Ruby
150 lines
5.8 KiB
Ruby
module ActiveRecord
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module Reflection # :nodoc:
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def self.included(base)
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base.extend(ClassMethods)
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end
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# Reflection allows you to interrogate Active Record classes and objects about their associations and aggregations.
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# This information can, for example, be used in a form builder that took an Active Record object and created input
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# fields for all of the attributes depending on their type and displayed the associations to other objects.
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#
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# You can find the interface for the AggregateReflection and AssociationReflection classes in the abstract MacroReflection class.
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module ClassMethods
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def create_reflection(macro, name, options, active_record)
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case macro
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when :has_many, :belongs_to, :has_one, :has_and_belongs_to_many
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reflections[name] = AssociationReflection.new(macro, name, options, active_record)
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when :composed_of
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reflections[name] = AggregateReflection.new(macro, name, options, active_record)
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end
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end
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def reflections
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read_inheritable_attribute(:reflections) or write_inheritable_attribute(:reflections, {})
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end
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# Returns an array of AggregateReflection objects for all the aggregations in the class.
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def reflect_on_all_aggregations
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reflections.values.select { |reflection| reflection.is_a?(AggregateReflection) }
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end
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# Returns the AggregateReflection object for the named +aggregation+ (use the symbol). Example:
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# Account.reflect_on_aggregation(:balance) # returns the balance AggregateReflection
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def reflect_on_aggregation(aggregation)
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reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil
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end
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# Returns an array of AssociationReflection objects for all the aggregations in the class. If you only want to reflect on a
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# certain association type, pass in the symbol for that as the first parameter.
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def reflect_on_all_associations(macro = nil)
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association_reflections = reflections.values.select { |reflection| reflection.is_a?(AssociationReflection) }
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macro ? association_reflections.select { |reflection| reflection.macro == macro } : association_reflections
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end
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# Returns the AssociationReflection object for the named +aggregation+ (use the symbol). Example:
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# Account.reflect_on_association(:owner) # returns the owner AssociationReflection
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def reflect_on_association(association)
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reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
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end
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end
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# Abstract base class for AggregateReflection and AssociationReflection that describes the interface available for both of
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# those classes. Objects of AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
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class MacroReflection
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attr_reader :active_record
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def initialize(macro, name, options, active_record)
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@macro, @name, @options, @active_record = macro, name, options, active_record
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end
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# Returns the name of the macro, so it would return :balance for "composed_of :balance, :class_name => 'Money'" or
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# :clients for "has_many :clients".
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def name
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@name
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end
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# Returns the name of the macro, so it would return :composed_of for
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# "composed_of :balance, :class_name => 'Money'" or :has_many for "has_many :clients".
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def macro
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@macro
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end
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# Returns the hash of options used for the macro, so it would return { :class_name => "Money" } for
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# "composed_of :balance, :class_name => 'Money'" or {} for "has_many :clients".
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def options
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@options
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end
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# Returns the class for the macro, so "composed_of :balance, :class_name => 'Money'" would return the Money class and
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# "has_many :clients" would return the Client class.
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def klass() end
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def class_name
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@class_name ||= name_to_class_name(name.id2name)
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end
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def require_class
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require_association(class_name.underscore) if class_name
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end
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def ==(other_aggregation)
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name == other_aggregation.name && other_aggregation.options && active_record == other_aggregation.active_record
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end
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end
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# Holds all the meta-data about an aggregation as it was specified in the Active Record class.
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class AggregateReflection < MacroReflection #:nodoc:
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def klass
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@klass ||= Object.const_get(class_name)
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end
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private
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def name_to_class_name(name)
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name.capitalize.gsub(/_(.)/) { |s| $1.capitalize }
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end
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end
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# Holds all the meta-data about an association as it was specified in the Active Record class.
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class AssociationReflection < MacroReflection #:nodoc:
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def klass
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@klass ||= active_record.send(:compute_type, class_name)
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end
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def table_name
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@table_name ||= klass.table_name
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end
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def primary_key_name
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return @primary_key_name if @primary_key_name
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case macro
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when :belongs_to
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@primary_key_name = options[:foreign_key] || class_name.foreign_key
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else
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@primary_key_name = options[:foreign_key] || active_record.name.foreign_key
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end
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end
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def association_foreign_key
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@association_foreign_key ||= @options[:association_foreign_key] || class_name.foreign_key
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end
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private
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def name_to_class_name(name)
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if name =~ /::/
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name
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else
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if options[:class_name]
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class_name = options[:class_name]
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else
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class_name = name.to_s.camelize
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class_name = class_name.singularize if [ :has_many, :has_and_belongs_to_many ].include?(macro)
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end
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active_record.send(:type_name_with_module, class_name)
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end
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end
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end
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end
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end
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