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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
class_attribute :aggregate_reflections
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._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 the ability to examine the associations and aggregations of
# Active Record classes and objects. This information, for example,
# can 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
ref = {}
_reflections.each do |name, reflection|
parent_reflection = reflection.parent_reflection
if parent_reflection
parent_name = parent_reflection.name
ref[parent_name.to_s] = parent_reflection
else
ref[name] = reflection
end
end
ref
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
#
# @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 <tt>:autosave</tt> enabled.
#
# @api public
def reflect_on_all_autosave_associations
reflections.values.select { |reflection| reflection.options[:autosave] }
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.
#
# <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).to_s
end
JoinKeys = Struct.new(:key, :foreign_key) # :nodoc:
def join_keys(association_klass)
JoinKeys.new(foreign_key, active_record_primary_key)
end
def constraints
scope_chain.flatten
end
def alias_candidate(name)
"#{plural_name}_#{name}"
end
end
# Base class for AggregateReflection and AssociationReflection. Objects of
# AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
#
# MacroReflection
# AggregateReflection
# AssociationReflection
# HasManyReflection
# HasOneReflection
# BelongsToReflection
# ThroughReflection
class MacroReflection < AbstractReflection
# 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
attr_reader :scope
# 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 <tt>{}</tt>
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.
#
# <tt>composed_of :balance, class_name: 'Money'</tt> returns the Money class
# <tt>has_many :clients</tt> 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
#
# <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 ||= 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 # 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_validity_of_inverse!
unless polymorphic?
if has_inverse? && inverse_of.nil?
raise InverseOfAssociationNotFoundError.new(self)
end
end
end
def check_preloadable!
return unless scope
if scope.arity > 0
raise ArgumentError, <<-MSG.squish
The association scope '#{name}' is instance dependent (the scope
block takes an argument). Preloading instance dependent scopes is
not supported.
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
# This is for clearing cache on the reflection. Useful for tests that need to compare
# SQL queries on associations.
def clear_association_scope_cache # :nodoc:
@association_scope_cache.clear
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 inverse_of
return unless inverse_name
@inverse_of ||= klass._reflect_on_association 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.
#
# <tt>has_many :clients</tt> returns <tt>:has_many</tt>
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
# <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 || 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
# <tt>inverse_of</tt> option cannot be set to false. Second, we must
# have <tt>has_many</tt>, <tt>has_one</tt>, <tt>belongs_to</tt> associations.
# Third, we must not have options such as <tt>:polymorphic</tt> or
# <tt>:foreign_key</tt> 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(association_klass)
key = polymorphic? ? association_primary_key(association_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 <tt>:belongs_to</tt> or <tt>:has_many</tt>.
#
# 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
# # => <ActiveRecord::Reflection::BelongsToReflection: @name=:tag, @active_record=Tagging, @plural_name="tags">
#
def source_reflection
through_reflection.klass._reflect_on_association(source_reflection_name)
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)
# tags_reflection.through_reflection
# # => <ActiveRecord::Reflection::HasManyReflection: @name=:taggings, @active_record=Post, @plural_name="taggings">
#
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
# # => [<ActiveRecord::Reflection::ThroughReflection: @delegate_reflection=#<ActiveRecord::Reflection::HasManyReflection: @name=:tags...>,
# <ActiveRecord::Reflection::HasManyReflection: @name=:taggings, @options={}, @active_record=Post>]
#
def chain
@chain ||= begin
a = source_reflection.chain
b = through_reflection.chain.map(&:dup)
if options[:source_type]
b[0] = PolymorphicReflection.new(b[0], self)
end
chain = a + b
chain[0] = self # Use self so we don't lose the information from :source_type
chain
end
end
# This is for clearing cache on the reflection. Useful for tests that need to compare
# SQL queries on associations.
def clear_association_scope_cache # :nodoc:
@chain = nil
delegate_reflection.clear_association_scope_cache
source_reflection.clear_association_scope_cache
through_reflection.clear_association_scope_cache
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(association_klass)
source_reflection.join_keys(association_klass)
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 <tt>:through</tt> 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(&: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
def constraints
scope_chain = source_reflection.constraints
scope_chain << scope if scope
scope_chain
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
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
class PolymorphicReflection < ThroughReflection # :nodoc:
def initialize(reflection, previous_reflection)
@reflection = reflection
@previous_reflection = previous_reflection
end
def klass
@reflection.klass
end
def scope
@reflection.scope
end
def table_name
@reflection.table_name
end
def plural_name
@reflection.plural_name
end
def join_keys(association_klass)
@reflection.join_keys(association_klass)
end
def type
@reflection.type
end
def constraints
[source_type_info]
end
def source_type_info
type = @previous_reflection.foreign_type
source_type = @previous_reflection.options[:source_type]
lambda { |object| where(type => source_type) }
end
end
class RuntimeReflection < PolymorphicReflection # :nodoc:
attr_accessor :next
def initialize(reflection, association)
@reflection = reflection
@association = association
end
def klass
@association.klass
end
def table_name
klass.table_name
end
def constraints
@reflection.constraints
end
def source_type_info
@reflection.source_type_info
end
def alias_candidate(name)
"#{plural_name}_#{name}_join"
end
def alias_name
Arel::Table.new(table_name)
end
def all_includes; yield; end
end
end
end
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