Skip to content
Find file
Fetching contributors…
Cannot retrieve contributors at this time
792 lines (677 sloc) 26.3 KB
require 'thread'
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)
case macro
when :has_many, :belongs_to, :has_one
klass = options[:through] ? ThroughReflection : AssociationReflection
when :composed_of
klass = AggregateReflection
end
klass.new(macro, name, scope, options, ar)
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 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
# 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_name, parent_reflection = reflection.parent_reflection
if parent_name
ref[parent_name] = 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
# Base class for AggregateReflection and AssociationReflection. Objects of
# AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods.
#
# MacroReflection
# AggregateReflection
# AssociationReflection
# ThroughReflection
class MacroReflection
# 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
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(macro, name, scope, options, active_record)
@macro = macro
@name = name
@scope = scope
@options = options
@active_record = active_record
@klass = options[: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 ||= 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).to_s
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
JoinKeys = Struct.new(:key, :foreign_key) # :nodoc:
def join_keys(assoc_klass)
if source_macro == :belongs_to
if polymorphic?
reflection_key = association_primary_key(assoc_klass)
else
reflection_key = association_primary_key
end
reflection_foreign_key = foreign_key
else
reflection_key = foreign_key
reflection_foreign_key = active_record_primary_key
end
JoinKeys.new(reflection_key, reflection_foreign_key)
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 ||= active_record.send(:compute_type, class_name)
end
attr_reader :type, :foreign_type
attr_accessor :parent_reflection # [:name, Reflection]
def initialize(macro, name, scope, options, active_record)
super
@collection = macro == :has_many
@automatic_inverse_of = nil
@type = options[:as] && "#{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
# 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 constructable? # :nodoc:
@constructable
end
def table_name
klass.table_name
end
def quoted_table_name
klass.quoted_table_name
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 primary_key_type
klass.type_for_attribute(klass.primary_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
ActiveSupport::Deprecation.warn <<-WARNING
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.
WARNING
end
end
alias :check_eager_loadable! :check_preloadable!
def join_id_for(owner) #:nodoc:
key = (source_macro == :belongs_to) ? foreign_key : active_record_primary_key
owner[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
alias :source_macro :macro
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 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 || collection?)
end
# Returns +true+ if +self+ is a +belongs_to+ reflection.
def belongs_to?
macro == :belongs_to
end
# Returns +true+ if +self+ is a +has_one+ reflection.
def has_one?
macro == :has_one
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).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
[active_record.table_name, klass.table_name].sort.join("\0").gsub(/^(.*_)(.+)\0\1(.+)/, '\1\2_\3').gsub("\0", "_")
end
def primary_key(klass)
klass.primary_key || raise(UnknownPrimaryKey.new(klass))
end
end
class HasAndBelongsToManyReflection < AssociationReflection #:nodoc:
def initialize(macro, name, scope, options, active_record)
super
@collection = true
end
end
# Holds all the meta-data about a :through association as it was specified
# in the Active Record class.
class ThroughReflection < AssociationReflection #:nodoc:
delegate :foreign_key, :foreign_type, :association_foreign_key,
:active_record_primary_key, :type, :to => :source_reflection
def initialize(macro, name, scope, options, active_record)
super
@source_reflection_name = options[:source]
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::AssociationReflection: @macro=:belongs_to, @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::AssociationReflection: @macro=:has_many, @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: @macro=:has_many, @name=:tags, @options={:through=>:taggings}, @active_record=Post>,
# <ActiveRecord::Reflection::AssociationReflection: @macro=:has_many, @name=:taggings, @options={}, @active_record=Post>]
#
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]
through_scope_chain.first <<
through_reflection.klass.where(foreign_type => options[:source_type])
end
# Recursively fill out the rest of the array from the through reflection
scope_chain + through_scope_chain
end
end
# The macro used by the source association
def source_macro
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 <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 { |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 <<-eowarn
Ambiguous source reflection for through association. Please specify a :source
directive on your declaration like:
class #{active_record.name} < ActiveRecord::Base
#{macro} :#{name}, #{example_options}
end
eowarn
end
@source_reflection_name = names.first
end
def source_options
source_reflection.options
end
def through_options
through_reflection.options
end
def check_validity!
if through_reflection.nil?
raise HasManyThroughAssociationNotFoundError.new(active_record.name, self)
end
if through_reflection.polymorphic?
raise HasManyThroughAssociationPolymorphicThroughError.new(active_record.name, self)
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.actual_source_reflection
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
Jump to Line
Something went wrong with that request. Please try again.