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require 'active_support/core_ext/class/attribute'
require 'active_support/core_ext/module/deprecation'
module ActiveRecord
# = Active Record Reflection
module Reflection # :nodoc:
extend ActiveSupport::Concern
included do
class_attribute :reflections
self.reflections = {}
end
# 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.
module ClassMethods
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 an array of AggregateReflection objects for all the aggregations in the class.
def reflect_on_all_aggregations
reflections.values.grep(AggregateReflection)
end
# Returns the AggregateReflection object for the named +aggregation+ (use the symbol).
#
# Account.reflect_on_aggregation(:balance) # => the balance AggregateReflection
#
def reflect_on_aggregation(aggregation)
reflections[aggregation].is_a?(AggregateReflection) ? reflections[aggregation] : nil
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 (<tt>:has_many</tt>, <tt>:has_one</tt>,
# <tt>:belongs_to</tt>) 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
#
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 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
#
def reflect_on_association(association)
reflections[association].is_a?(AssociationReflection) ? reflections[association] : nil
end
# Returns an array of AssociationReflection objects for all associations which have <tt>:autosave</tt> enabled.
def reflect_on_all_autosave_associations
reflections.values.select { |reflection| reflection.options[:autosave] }
end
end
# Abstract base class for AggregateReflection and AssociationReflection. Objects of
# AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
class MacroReflection
attr_reader :active_record
def initialize(macro, name, options, active_record)
@macro, @name, @options, @active_record = macro, name, options, active_record
end
# Returns the name of the macro.
#
# <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>:balance</tt>
# <tt>has_many :clients</tt> returns <tt>:clients</tt>
attr_reader :name
# Returns the macro type.
#
# <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>:composed_of</tt>
# <tt>has_many :clients</tt> returns <tt>:has_many</tt>
attr_reader :macro
# Returns the hash of options used for the macro.
#
# <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>{ :class_name => "Money" }</tt>
# <tt>has_many :clients</tt> returns +{}+
attr_reader :options
# Returns the class for the macro.
#
# <tt>composed_of :balance, :class_name => 'Money'</tt> returns the Money class
# <tt>has_many :clients</tt> returns the Client class
def klass
@klass ||= class_name.constantize
end
# Returns the class name for the macro.
#
# <tt>composed_of :balance, :class_name => 'Money'</tt> returns <tt>'Money'</tt>
# <tt>has_many :clients</tt> returns <tt>'Client'</tt>
def class_name
@class_name ||= options[:class_name] || derive_class_name
end
# Returns +true+ if +self+ and +other_aggregation+ have the same +name+ attribute, +active_record+ attribute,
# and +other_aggregation+ has an options hash assigned to it.
def ==(other_aggregation)
other_aggregation.kind_of?(self.class) && name == other_aggregation.name && other_aggregation.options && active_record == other_aggregation.active_record
end
def sanitized_conditions #:nodoc:
@sanitized_conditions ||= klass.send(:sanitize_sql, options[:conditions]) if options[:conditions]
end
private
def derive_class_name
name.to_s.camelize
end
end
# Holds all the meta-data about an aggregation as it was specified in the
# Active Record class.
class AggregateReflection < MacroReflection #:nodoc:
end
# Holds all the meta-data about an association as it was specified in the
# Active Record class.
class AssociationReflection < MacroReflection #:nodoc:
# Returns the target association's class.
#
# class Author < ActiveRecord::Base
# has_many :books
# end
#
# Author.reflect_on_association(:books).klass
# # => Book
#
# <b>Note:</b> Do not call +klass.new+ or +klass.create+ to instantiate
# a new association object. Use +build_association+ or +create_association+
# instead. This allows plugins to hook into association object creation.
def klass
@klass ||= active_record.send(:compute_type, class_name)
end
def initialize(macro, name, options, active_record)
super
@collection = [:has_many, :has_and_belongs_to_many].include?(macro)
end
# Returns a new, unsaved instance of the associated class. +options+ will
# be passed to the class's constructor.
def build_association(*options)
klass.new(*options)
end
# Creates a new instance of the associated class, and immediately saves it
# with ActiveRecord::Base#save. +options+ will be passed to the class's
# creation method. Returns the newly created object.
def create_association(*options)
klass.create(*options)
end
# Creates a new instance of the associated class, and immediately saves it
# with ActiveRecord::Base#save!. +options+ will be passed to the class's
# creation method. If the created record doesn't pass validations, then an
# exception will be raised.
#
# Returns the newly created object.
def create_association!(*options)
klass.create!(*options)
end
def table_name
@table_name ||= klass.table_name
end
def quoted_table_name
@quoted_table_name ||= klass.quoted_table_name
end
def foreign_key
@foreign_key ||= options[:foreign_key] || derive_foreign_key
end
def primary_key_name
foreign_key
end
deprecate :primary_key_name => :foreign_key
def foreign_type
@foreign_type ||= options[:foreign_type] || "#{name}_type"
end
def primary_key_column
@primary_key_column ||= klass.columns.find { |c| c.name == klass.primary_key }
end
def association_foreign_key
@association_foreign_key ||= options[:association_foreign_key] || class_name.foreign_key
end
def association_primary_key
@association_primary_key ||=
options[:primary_key] ||
!options[:polymorphic] && klass.primary_key ||
'id'
end
def active_record_primary_key
@active_record_primary_key ||= options[:primary_key] || active_record.primary_key
end
def counter_cache_column
if options[:counter_cache] == true
"#{active_record.name.demodulize.underscore.pluralize}_count"
elsif options[:counter_cache]
options[:counter_cache]
end
end
def columns(tbl_name, log_msg)
@columns ||= klass.connection.columns(tbl_name, log_msg)
end
def reset_column_information
@columns = nil
end
def check_validity!
check_validity_of_inverse!
end
def check_validity_of_inverse!
unless options[:polymorphic]
if has_inverse? && inverse_of.nil?
raise InverseOfAssociationNotFoundError.new(self)
end
end
end
def through_reflection
false
end
def through_reflection_foreign_key
end
def source_reflection
nil
end
def has_inverse?
@options[:inverse_of]
end
def inverse_of
if has_inverse?
@inverse_of ||= klass.reflect_on_association(options[:inverse_of])
end
end
def polymorphic_inverse_of(associated_class)
if has_inverse?
if inverse_relationship = associated_class.reflect_on_association(options[:inverse_of])
inverse_relationship
else
raise InverseOfAssociationNotFoundError.new(self, associated_class)
end
end
end
# Returns whether or not this association reflection is for a collection
# association. Returns +true+ if the +macro+ is either +has_many+ or
# +has_and_belongs_to_many+, +false+ otherwise.
def collection?
@collection
end
# Returns whether or not the association should be validated as part of
# the parent's validation.
#
# Unless you explicitly disable validation with
# <tt>:validate => false</tt>, validation will take place when:
#
# * you explicitly enable validation; <tt>:validate => true</tt>
# * you use autosave; <tt>:autosave => true</tt>
# * the association is a +has_many+ association
def validate?
!options[:validate].nil? ? options[:validate] : (options[:autosave] == true || macro == :has_many)
end
# Returns +true+ if +self+ is a +belongs_to+ reflection.
def belongs_to?
macro == :belongs_to
end
def proxy_class
case macro
when :belongs_to
if options[:polymorphic]
Associations::BelongsToPolymorphicAssociation
else
Associations::BelongsToAssociation
end
when :has_and_belongs_to_many
Associations::HasAndBelongsToManyAssociation
when :has_many
if options[:through]
Associations::HasManyThroughAssociation
else
Associations::HasManyAssociation
end
when :has_one
if options[:through]
Associations::HasOneThroughAssociation
else
Associations::HasOneAssociation
end
end
end
private
def derive_class_name
class_name = name.to_s.camelize
class_name = class_name.singularize if collection?
class_name
end
def derive_foreign_key
if belongs_to?
"#{name}_id"
elsif options[:as]
"#{options[:as]}_id"
else
active_record.name.foreign_key
end
end
end
# Holds all the meta-data about a :through association as it was specified
# in the Active Record class.
class ThroughReflection < AssociationReflection #:nodoc:
# Gets the source of the through reflection. It checks both a singularized
# and pluralized form for <tt>:belongs_to</tt> or <tt>:has_many</tt>.
#
# class Post < ActiveRecord::Base
# has_many :taggings
# has_many :tags, :through => :taggings
# end
#
def source_reflection
@source_reflection ||= source_reflection_names.collect { |name| through_reflection.klass.reflect_on_association(name) }.compact.first
end
# Returns the AssociationReflection object specified in the <tt>:through</tt> option
# of a HasManyThrough or HasOneThrough association.
#
# class Post < ActiveRecord::Base
# has_many :taggings
# has_many :tags, :through => :taggings
# end
#
# tags_reflection = Post.reflect_on_association(:tags)
# taggings_reflection = tags_reflection.through_reflection
#
def through_reflection
@through_reflection ||= active_record.reflect_on_association(options[:through])
end
# Gets an array of possible <tt>:through</tt> source reflection names:
#
# [:singularized, :pluralized]
#
def source_reflection_names
@source_reflection_names ||= (options[:source] ? [options[:source]] : [name.to_s.singularize, name]).collect { |n| n.to_sym }
end
def check_validity!
if through_reflection.nil?
raise HasManyThroughAssociationNotFoundError.new(active_record.name, self)
end
if through_reflection.options[:polymorphic]
raise HasManyThroughAssociationPolymorphicThroughError.new(active_record.name, self)
end
if source_reflection.nil?
raise HasManyThroughSourceAssociationNotFoundError.new(self)
end
if options[:source_type] && source_reflection.options[:polymorphic].nil?
raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
end
if source_reflection.options[:polymorphic] && options[:source_type].nil?
raise HasManyThroughAssociationPolymorphicSourceError.new(active_record.name, self, source_reflection)
end
unless [:belongs_to, :has_many, :has_one].include?(source_reflection.macro) && source_reflection.options[:through].nil?
raise HasManyThroughSourceAssociationMacroError.new(self)
end
if macro == :has_one && through_reflection.collection?
raise HasOneThroughCantAssociateThroughCollection.new(active_record.name, self, through_reflection)
end
check_validity_of_inverse!
end
def through_reflection_primary_key
through_reflection.belongs_to? ? through_reflection.klass.primary_key : through_reflection.foreign_key
end
def through_reflection_foreign_key
through_reflection.foreign_key if through_reflection.belongs_to?
end
private
def derive_class_name
# get the class_name of the belongs_to association of the through reflection
options[:source_type] || source_reflection.class_name
end
end
end
end
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