require 'thread'
require 'active_support/core_ext/string/filters'
module ActiveRecord
# = Active Record Reflection
module Reflection # :nodoc:
extend ActiveSupport::Concern
included do
class_attribute :_reflections, instance_writer: false
class_attribute :aggregate_reflections, instance_writer: false
self._reflections = {}
self.aggregate_reflections = {}
end
def self.create(macro, name, scope, options, ar)
klass = case macro
when :composed_of
AggregateReflection
when :has_many
HasManyReflection
when :has_one
HasOneReflection
when :belongs_to
BelongsToReflection
else
raise "Unsupported Macro: #{macro}"
end
reflection = klass.new(name, scope, options, ar)
options[:through] ? ThroughReflection.new(reflection) : reflection
end
def self.add_reflection(ar, name, reflection)
ar.clear_reflections_cache
ar._reflections = ar._reflections.merge(name.to_s => reflection)
end
def self.add_aggregate_reflection(ar, name, reflection)
ar.aggregate_reflections = ar.aggregate_reflections.merge(name.to_s => reflection)
end
# \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.
module ClassMethods
# Returns an array of AggregateReflection objects for all the aggregations in the class.
def reflect_on_all_aggregations
aggregate_reflections.values
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)
aggregate_reflections[aggregation.to_s]
end
# Returns a Hash of name of the reflection as the key and a AssociationReflection as the value.
#
# Account.reflections # => {"balance" => AggregateReflection}
#
# @api public
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
# 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
def reflect_on_all_associations(macro = nil)
association_reflections = reflections.values
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
#
# @api public
def reflect_on_association(association)
reflections[association.to_s]
end
# @api private
def _reflect_on_association(association) #:nodoc:
_reflections[association.to_s]
end
# Returns an array of AssociationReflection objects for all associations which have :autosave enabled.
#
# @api public
def reflect_on_all_autosave_associations
reflections.values.select { |reflection| reflection.options[:autosave] }
end
def clear_reflections_cache #:nodoc:
@__reflections = nil
end
end
# Holds all the methods that are shared between MacroReflection, AssociationReflection
# and ThroughReflection
class AbstractReflection # :nodoc:
def table_name
klass.table_name
end
# Returns a new, unsaved instance of the associated class. +attributes+ will
# be passed to the class's constructor.
def build_association(attributes, &block)
klass.new(attributes, &block)
end
def quoted_table_name
klass.quoted_table_name
end
def primary_key_type
klass.type_for_attribute(klass.primary_key)
end
# Returns the class name for the macro.
#
# composed_of :balance, class_name: 'Money' returns 'Money'
# has_many :clients returns 'Client'
def class_name
@class_name ||= (options[:class_name] || derive_class_name).to_s
end
JoinKeys = Struct.new(:key, :foreign_key) # :nodoc:
def join_keys(assoc_klass)
JoinKeys.new(foreign_key, active_record_primary_key)
end
def source_macro
ActiveSupport::Deprecation.warn(<<-MSG.squish)
ActiveRecord::Base.source_macro is deprecated and will be removed
without replacement.
MSG
macro
end
def inverse_of
return unless inverse_name
@inverse_of ||= klass._reflect_on_association inverse_name
end
def check_validity_of_inverse!
unless polymorphic?
if has_inverse? && inverse_of.nil?
raise InverseOfAssociationNotFoundError.new(self)
end
end
end
end
# Base class for AggregateReflection and AssociationReflection. Objects of
# AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
#
# MacroReflection
# AssociationReflection
# AggregateReflection
# HasManyReflection
# HasOneReflection
# BelongsToReflection
# ThroughReflection
class MacroReflection < AbstractReflection
# Returns the name of the macro.
#
# composed_of :balance, class_name: 'Money' returns :balance
# has_many :clients returns :clients
attr_reader :name
attr_reader :scope
# Returns the hash of options used for the macro.
#
# composed_of :balance, class_name: 'Money' returns { class_name: "Money" }
# has_many :clients returns {}
attr_reader :options
attr_reader :active_record
attr_reader :plural_name # :nodoc:
def initialize(name, scope, options, active_record)
@name = name
@scope = scope
@options = options
@active_record = active_record
@klass = options[:anonymous_class]
@plural_name = active_record.pluralize_table_names ?
name.to_s.pluralize : name.to_s
end
def autosave=(autosave)
@automatic_inverse_of = false
@options[:autosave] = autosave
_, parent_reflection = self.parent_reflection
if parent_reflection
parent_reflection.autosave = autosave
end
end
# Returns the class for the macro.
#
# composed_of :balance, class_name: 'Money' returns the Money class
# has_many :clients returns the Client class
def klass
@klass ||= compute_class(class_name)
end
def compute_class(name)
name.constantize
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)
super ||
other_aggregation.kind_of?(self.class) &&
name == other_aggregation.name &&
!other_aggregation.options.nil? &&
active_record == other_aggregation.active_record
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:
def mapping
mapping = options[:mapping] || [name, name]
mapping.first.is_a?(Array) ? mapping : [mapping]
end
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
#
# Note: 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 ||= compute_class(class_name)
end
def compute_class(name)
active_record.send(:compute_type, name)
end
attr_reader :type, :foreign_type
attr_accessor :parent_reflection # [:name, Reflection]
def initialize(name, scope, options, active_record)
super
@automatic_inverse_of = nil
@type = options[:as] && (options[:foreign_type] || "#{options[:as]}_type")
@foreign_type = options[:foreign_type] || "#{name}_type"
@constructable = calculate_constructable(macro, options)
@association_scope_cache = {}
@scope_lock = Mutex.new
end
def association_scope_cache(conn, owner)
key = conn.prepared_statements
if polymorphic?
key = [key, owner._read_attribute(@foreign_type)]
end
@association_scope_cache[key] ||= @scope_lock.synchronize {
@association_scope_cache[key] ||= yield
}
end
def constructable? # :nodoc:
@constructable
end
def join_table
@join_table ||= options[:join_table] || derive_join_table
end
def foreign_key
@foreign_key ||= options[:foreign_key] || derive_foreign_key
end
def association_foreign_key
@association_foreign_key ||= options[:association_foreign_key] || class_name.foreign_key
end
# klass option is necessary to support loading polymorphic associations
def association_primary_key(klass = nil)
options[:primary_key] || primary_key(klass || self.klass)
end
def active_record_primary_key
@active_record_primary_key ||= options[:primary_key] || primary_key(active_record)
end
def counter_cache_column
if options[:counter_cache] == true
"#{active_record.name.demodulize.underscore.pluralize}_count"
elsif options[:counter_cache]
options[:counter_cache].to_s
end
end
def check_validity!
check_validity_of_inverse!
end
def check_preloadable!
return unless scope
if scope.arity > 0
ActiveSupport::Deprecation.warn(<<-MSG.squish)
The association scope '#{name}' is instance dependent (the scope
block takes an argument). Preloading happens before the individual
instances are created. This means that there is no instance being
passed to the association scope. This will most likely result in
broken or incorrect behavior. Joining, Preloading and eager loading
of these associations is deprecated and will be removed in the future.
MSG
end
end
alias :check_eager_loadable! :check_preloadable!
def join_id_for(owner) # :nodoc:
owner[active_record_primary_key]
end
def through_reflection
nil
end
def source_reflection
self
end
# A chain of reflections from this one back to the owner. For more see the explanation in
# ThroughReflection.
def chain
[self]
end
def nested?
false
end
# An array of arrays of scopes. Each item in the outside array corresponds to a reflection
# in the #chain.
def scope_chain
scope ? [[scope]] : [[]]
end
def has_inverse?
inverse_name
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 the macro type.
#
# has_many :clients returns :has_many
def macro; raise NotImplementedError; 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?
false
end
# Returns whether or not the association should be validated as part of
# the parent's validation.
#
# Unless you explicitly disable validation with
# validate: false, validation will take place when:
#
# * you explicitly enable validation; validate: true
# * you use autosave; autosave: true
# * the association is a +has_many+ association
def validate?
!options[:validate].nil? ? options[:validate] : (options[:autosave] == true || collection?)
end
# Returns +true+ if +self+ is a +belongs_to+ reflection.
def belongs_to?; false; end
# Returns +true+ if +self+ is a +has_one+ reflection.
def has_one?; false; end
def association_class
case macro
when :belongs_to
if polymorphic?
Associations::BelongsToPolymorphicAssociation
else
Associations::BelongsToAssociation
end
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
def polymorphic?
options[:polymorphic]
end
VALID_AUTOMATIC_INVERSE_MACROS = [:has_many, :has_one, :belongs_to]
INVALID_AUTOMATIC_INVERSE_OPTIONS = [:conditions, :through, :polymorphic, :foreign_key]
protected
def actual_source_reflection # FIXME: this is a horrible name
self
end
private
def calculate_constructable(macro, options)
case macro
when :belongs_to
!polymorphic?
when :has_one
!options[:through]
else
true
end
end
# Attempts to find the inverse association name automatically.
# If it cannot find a suitable inverse association name, it returns
# nil.
def inverse_name
options.fetch(:inverse_of) do
if @automatic_inverse_of == false
nil
else
@automatic_inverse_of ||= automatic_inverse_of
end
end
end
# returns either nil or the inverse association name that it finds.
def automatic_inverse_of
if can_find_inverse_of_automatically?(self)
inverse_name = ActiveSupport::Inflector.underscore(options[:as] || active_record.name.demodulize).to_sym
begin
reflection = klass._reflect_on_association(inverse_name)
rescue NameError
# Give up: we couldn't compute the klass type so we won't be able
# to find any associations either.
reflection = false
end
if valid_inverse_reflection?(reflection)
return inverse_name
end
end
false
end
# Checks if the inverse reflection that is returned from the
# +automatic_inverse_of+ method is a valid reflection. We must
# make sure that the reflection's active_record name matches up
# with the current reflection's klass name.
#
# Note: klass will always be valid because when there's a NameError
# from calling +klass+, +reflection+ will already be set to false.
def valid_inverse_reflection?(reflection)
reflection &&
klass.name == reflection.active_record.name &&
can_find_inverse_of_automatically?(reflection)
end
# Checks to see if the reflection doesn't have any options that prevent
# us from being able to guess the inverse automatically. First, the
# inverse_of option cannot be set to false. Second, we must
# have has_many, has_one, belongs_to associations.
# Third, we must not have options such as :polymorphic or
# :foreign_key which prevent us from correctly guessing the
# inverse association.
#
# Anything with a scope can additionally ruin our attempt at finding an
# inverse, so we exclude reflections with scopes.
def can_find_inverse_of_automatically?(reflection)
reflection.options[:inverse_of] != false &&
VALID_AUTOMATIC_INVERSE_MACROS.include?(reflection.macro) &&
!INVALID_AUTOMATIC_INVERSE_OPTIONS.any? { |opt| reflection.options[opt] } &&
!reflection.scope
end
def derive_class_name
class_name = name.to_s
class_name = class_name.singularize if collection?
class_name.camelize
end
def derive_foreign_key
if belongs_to?
"#{name}_id"
elsif options[:as]
"#{options[:as]}_id"
else
active_record.name.foreign_key
end
end
def derive_join_table
ModelSchema.derive_join_table_name active_record.table_name, klass.table_name
end
def primary_key(klass)
klass.primary_key || raise(UnknownPrimaryKey.new(klass))
end
end
class HasManyReflection < AssociationReflection # :nodoc:
def initialize(name, scope, options, active_record)
super(name, scope, options, active_record)
end
def macro; :has_many; end
def collection?; true; end
end
class HasOneReflection < AssociationReflection # :nodoc:
def initialize(name, scope, options, active_record)
super(name, scope, options, active_record)
end
def macro; :has_one; end
def has_one?; true; end
end
class BelongsToReflection < AssociationReflection # :nodoc:
def initialize(name, scope, options, active_record)
super(name, scope, options, active_record)
end
def macro; :belongs_to; end
def belongs_to?; true; end
def join_keys(assoc_klass)
key = polymorphic? ? association_primary_key(assoc_klass) : association_primary_key
JoinKeys.new(key, foreign_key)
end
def join_id_for(owner) # :nodoc:
owner[foreign_key]
end
end
class HasAndBelongsToManyReflection < AssociationReflection # :nodoc:
def initialize(name, scope, options, active_record)
super
end
def macro; :has_and_belongs_to_many; end
def collection?
true
end
end
# Holds all the meta-data about a :through association as it was specified
# in the Active Record class.
class ThroughReflection < AbstractReflection #:nodoc:
attr_reader :delegate_reflection
delegate :foreign_key, :foreign_type, :association_foreign_key,
:active_record_primary_key, :type, :to => :source_reflection
def initialize(delegate_reflection)
@delegate_reflection = delegate_reflection
@klass = delegate_reflection.options[:anonymous_class]
@source_reflection_name = delegate_reflection.options[:source]
end
def klass
@klass ||= delegate_reflection.compute_class(class_name)
end
# Returns the source of the through reflection. It checks both a singularized
# and pluralized form for :belongs_to or :has_many.
#
# class Post < ActiveRecord::Base
# has_many :taggings
# has_many :tags, through: :taggings
# end
#
# class Tagging < ActiveRecord::Base
# belongs_to :post
# belongs_to :tag
# end
#
# tags_reflection = Post.reflect_on_association(:tags)
# tags_reflection.source_reflection
# # =>
#
def source_reflection
through_reflection.klass._reflect_on_association(source_reflection_name)
end
# Returns the AssociationReflection object specified in the :through 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)
# tags_reflection.through_reflection
# # =>
#
def through_reflection
active_record._reflect_on_association(options[:through])
end
# Returns an array of reflections which are involved in this association. Each item in the
# array corresponds to a table which will be part of the query for this association.
#
# The chain is built by recursively calling #chain on the source reflection and the through
# reflection. The base case for the recursion is a normal association, which just returns
# [self] as its #chain.
#
# class Post < ActiveRecord::Base
# has_many :taggings
# has_many :tags, through: :taggings
# end
#
# tags_reflection = Post.reflect_on_association(:tags)
# tags_reflection.chain
# # => [,
# ]
#
def chain
@chain ||= begin
a = source_reflection.chain
b = through_reflection.chain
chain = a + b
chain[0] = self # Use self so we don't lose the information from :source_type
chain
end
end
# Consider the following example:
#
# class Person
# has_many :articles
# has_many :comment_tags, through: :articles
# end
#
# class Article
# has_many :comments
# has_many :comment_tags, through: :comments, source: :tags
# end
#
# class Comment
# has_many :tags
# end
#
# There may be scopes on Person.comment_tags, Article.comment_tags and/or Comment.tags,
# but only Comment.tags will be represented in the #chain. So this method creates an array
# of scopes corresponding to the chain.
def scope_chain
@scope_chain ||= begin
scope_chain = source_reflection.scope_chain.map(&:dup)
# Add to it the scope from this reflection (if any)
scope_chain.first << scope if scope
through_scope_chain = through_reflection.scope_chain.map(&:dup)
if options[:source_type]
type = foreign_type
source_type = options[:source_type]
through_scope_chain.first << lambda { |object|
where(type => source_type)
}
end
# Recursively fill out the rest of the array from the through reflection
scope_chain + through_scope_chain
end
end
def join_keys(assoc_klass)
source_reflection.join_keys(assoc_klass)
end
# The macro used by the source association
def source_macro
ActiveSupport::Deprecation.warn(<<-MSG.squish)
ActiveRecord::Base.source_macro is deprecated and will be removed
without replacement.
MSG
source_reflection.source_macro
end
# A through association is nested if there would be more than one join table
def nested?
chain.length > 2
end
# We want to use the klass from this reflection, rather than just delegate straight to
# the source_reflection, because the source_reflection may be polymorphic. We still
# need to respect the source_reflection's :primary_key option, though.
def association_primary_key(klass = nil)
# Get the "actual" source reflection if the immediate source reflection has a
# source reflection itself
actual_source_reflection.options[:primary_key] || primary_key(klass || self.klass)
end
# Gets an array of possible :through source reflection names in both singular and plural form.
#
# class Post < ActiveRecord::Base
# has_many :taggings
# has_many :tags, through: :taggings
# end
#
# tags_reflection = Post.reflect_on_association(:tags)
# tags_reflection.source_reflection_names
# # => [:tag, :tags]
#
def source_reflection_names
options[:source] ? [options[:source]] : [name.to_s.singularize, name].uniq
end
def source_reflection_name # :nodoc:
return @source_reflection_name if @source_reflection_name
names = [name.to_s.singularize, name].collect { |n| n.to_sym }.uniq
names = names.find_all { |n|
through_reflection.klass._reflect_on_association(n)
}
if names.length > 1
example_options = options.dup
example_options[:source] = source_reflection_names.first
ActiveSupport::Deprecation.warn \
"Ambiguous source reflection for through association. Please " \
"specify a :source directive on your declaration like:\n" \
"\n" \
" class #{active_record.name} < ActiveRecord::Base\n" \
" #{macro} :#{name}, #{example_options}\n" \
" end"
end
@source_reflection_name = names.first
end
def source_options
source_reflection.options
end
def through_options
through_reflection.options
end
def join_id_for(owner) # :nodoc:
source_reflection.join_id_for(owner)
end
def check_validity!
if through_reflection.nil?
raise HasManyThroughAssociationNotFoundError.new(active_record.name, self)
end
if through_reflection.polymorphic?
if has_one?
raise HasOneAssociationPolymorphicThroughError.new(active_record.name, self)
else
raise HasManyThroughAssociationPolymorphicThroughError.new(active_record.name, self)
end
end
if source_reflection.nil?
raise HasManyThroughSourceAssociationNotFoundError.new(self)
end
if options[:source_type] && !source_reflection.polymorphic?
raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
end
if source_reflection.polymorphic? && options[:source_type].nil?
raise HasManyThroughAssociationPolymorphicSourceError.new(active_record.name, self, source_reflection)
end
if has_one? && through_reflection.collection?
raise HasOneThroughCantAssociateThroughCollection.new(active_record.name, self, through_reflection)
end
check_validity_of_inverse!
end
protected
def actual_source_reflection # FIXME: this is a horrible name
source_reflection.send(:actual_source_reflection)
end
def primary_key(klass)
klass.primary_key || raise(UnknownPrimaryKey.new(klass))
end
def inverse_name; delegate_reflection.send(:inverse_name); 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
delegate_methods = AssociationReflection.public_instance_methods -
public_instance_methods
delegate(*delegate_methods, to: :delegate_reflection)
end
end
end