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Diffstat (limited to 'activerecord/lib/active_record/reflection.rb')
| -rw-r--r-- | activerecord/lib/active_record/reflection.rb | 1056 |
1 files changed, 1056 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb new file mode 100644 index 0000000000..b2110f727c --- /dev/null +++ b/activerecord/lib/active_record/reflection.rb @@ -0,0 +1,1056 @@ +# frozen_string_literal: true + +require "active_support/core_ext/string/filters" +require "concurrent/map" + +module ActiveRecord + # = Active Record Reflection + module Reflection # :nodoc: + extend ActiveSupport::Concern + + included do + class_attribute :_reflections, instance_writer: false, default: {} + class_attribute :aggregate_reflections, instance_writer: false, default: {} + end + + class << self + def create(macro, name, scope, options, ar) + reflection = reflection_class_for(macro).new(name, scope, options, ar) + options[:through] ? ThroughReflection.new(reflection) : reflection + end + + def add_reflection(ar, name, reflection) + ar.clear_reflections_cache + name = name.to_s + ar._reflections = ar._reflections.except(name).merge!(name => reflection) + end + + def add_aggregate_reflection(ar, name, reflection) + ar.aggregate_reflections = ar.aggregate_reflections.merge(name.to_s => reflection) + end + + private + def reflection_class_for(macro) + case macro + when :composed_of + AggregateReflection + when :has_many + HasManyReflection + when :has_one + HasOneReflection + when :belongs_to + BelongsToReflection + else + raise "Unsupported Macro: #{macro}" + end + end + 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 an AssociationReflection as the value. + # + # Account.reflections # => {"balance" => AggregateReflection} + # + def reflections + @__reflections ||= begin + 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 + 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 + association_reflections.select! { |reflection| reflection.macro == macro } if 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.to_s] + end + + 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. + 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 and ThroughReflection. + # + # AbstractReflection + # MacroReflection + # AggregateReflection + # AssociationReflection + # HasManyReflection + # HasOneReflection + # BelongsToReflection + # HasAndBelongsToManyReflection + # ThroughReflection + # PolymorphicReflection + # RuntimeReflection + class AbstractReflection # :nodoc: + def through_reflection? + false + end + + 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 + + # 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 + @join_keys ||= get_join_keys(klass) + end + + # Returns a list of scopes that should be applied for this Reflection + # object when querying the database. + def scopes + scope ? [scope] : [] + end + + def build_join_constraint(table, foreign_table) + key = join_keys.key + foreign_key = join_keys.foreign_key + + constraint = table[key].eq(foreign_table[foreign_key]) + + if klass.finder_needs_type_condition? + table.create_and([constraint, klass.send(:type_condition, table)]) + else + constraint + end + end + + def join_scope(table, foreign_klass) + predicate_builder = predicate_builder(table) + scope_chain_items = join_scopes(table, predicate_builder) + klass_scope = klass_join_scope(table, predicate_builder) + + if type + klass_scope.where!(type => foreign_klass.polymorphic_name) + end + + scope_chain_items.inject(klass_scope, &:merge!) + end + + def join_scopes(table, predicate_builder) # :nodoc: + if scope + [scope_for(build_scope(table, predicate_builder))] + else + [] + end + end + + def klass_join_scope(table, predicate_builder) # :nodoc: + relation = build_scope(table, predicate_builder) + klass.scope_for_association(relation) + end + + def constraints + chain.flat_map(&:scopes) + end + + def counter_cache_column + if belongs_to? + if options[:counter_cache] == true + "#{active_record.name.demodulize.underscore.pluralize}_count" + elsif options[:counter_cache] + options[:counter_cache].to_s + end + else + options[:counter_cache] ? options[:counter_cache].to_s : "#{name}_count" + end + 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 + + # This shit is nasty. We need to avoid the following situation: + # + # * An associated record is deleted via record.destroy + # * Hence the callbacks run, and they find a belongs_to on the record with a + # :counter_cache options which points back at our owner. So they update the + # counter cache. + # * In which case, we must make sure to *not* update the counter cache, or else + # it will be decremented twice. + # + # Hence this method. + def inverse_which_updates_counter_cache + return @inverse_which_updates_counter_cache if defined?(@inverse_which_updates_counter_cache) + @inverse_which_updates_counter_cache = klass.reflect_on_all_associations(:belongs_to).find do |inverse| + inverse.counter_cache_column == counter_cache_column + end + end + alias inverse_updates_counter_cache? inverse_which_updates_counter_cache + + def inverse_updates_counter_in_memory? + inverse_of && inverse_which_updates_counter_cache == inverse_of + end + + # Returns whether a counter cache should be used for this association. + # + # The counter_cache option must be given on either the owner or inverse + # association, and the column must be present on the owner. + def has_cached_counter? + options[:counter_cache] || + inverse_which_updates_counter_cache && inverse_which_updates_counter_cache.options[:counter_cache] && + !!active_record.columns_hash[counter_cache_column] + end + + def counter_must_be_updated_by_has_many? + !inverse_updates_counter_in_memory? && has_cached_counter? + end + + def alias_candidate(name) + "#{plural_name}_#{name}" + end + + def chain + collect_join_chain + end + + def get_join_keys(association_klass) + JoinKeys.new(join_primary_key(association_klass), join_foreign_key) + end + + def build_scope(table, predicate_builder = predicate_builder(table)) + Relation.create( + klass, + table: table, + predicate_builder: predicate_builder + ) + end + + def join_primary_key(*) + foreign_key + end + + def join_foreign_key + active_record_primary_key + end + + protected + def actual_source_reflection # FIXME: this is a horrible name + self + end + + private + def predicate_builder(table) + PredicateBuilder.new(TableMetadata.new(klass, table)) + end + + def primary_key(klass) + klass.primary_key || raise(UnknownPrimaryKey.new(klass)) + end + end + + # Base class for AggregateReflection and AssociationReflection. Objects of + # AggregateReflection and AssociationReflection are returned by the Reflection::ClassMethods. + 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) + @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 + # + # class Company < ActiveRecord::Base + # has_many :clients + # end + # + # Company.reflect_on_association(:clients).klass + # # => Client + # + # <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) + 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 + + def scope_for(relation, owner = nil) + relation.instance_exec(owner, &scope) || relation + end + + private + def derive_class_name + name.to_s.camelize + end + end + + # Holds all the metadata 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 metadata about an association as it was specified in the + # Active Record class. + class AssociationReflection < MacroReflection #:nodoc: + def compute_class(name) + if polymorphic? + raise ArgumentError, "Polymorphic associations do not support computing the class." + end + 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 + @type = options[:as] && (options[:foreign_type] || "#{options[:as]}_type") + @foreign_type = options[:polymorphic] && (options[:foreign_type] || "#{name}_type") + @constructable = calculate_constructable(macro, options) + @association_scope_cache = Concurrent::Map.new + + if options[:class_name] && options[:class_name].class == Class + raise ArgumentError, "A class was passed to `:class_name` but we are expecting a string." + end + end + + def association_scope_cache(conn, owner, &block) + key = conn.prepared_statements + if polymorphic? + key = [key, owner._read_attribute(@foreign_type)] + end + @association_scope_cache.compute_if_absent(key) { StatementCache.create(conn, &block) } + 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.freeze + 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 check_validity! + check_validity_of_inverse! + 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[join_foreign_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 collect_join_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 + + def has_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. + # + # <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; raise NotImplementedError; end + + def polymorphic? + options[:polymorphic] + end + + VALID_AUTOMATIC_INVERSE_MACROS = [:has_many, :has_one, :belongs_to] + INVALID_AUTOMATIC_INVERSE_OPTIONS = [:through, :foreign_key] + + def add_as_source(seed) + seed + end + + def add_as_polymorphic_through(reflection, seed) + seed + [PolymorphicReflection.new(self, reflection)] + end + + def add_as_through(seed) + seed + [self] + end + + def extensions + Array(options[:extend]) + end + + private + + def calculate_constructable(macro, options) + true + end + + # Attempts to find the inverse association name automatically. + # If it cannot find a suitable inverse association name, it returns + # +nil+. + def inverse_name + unless defined?(@inverse_name) + @inverse_name = options.fetch(:inverse_of) { automatic_inverse_of } + end + + @inverse_name + end + + # returns either +nil+ or the inverse association name that it finds. + def automatic_inverse_of + return unless can_find_inverse_of_automatically?(self) + + inverse_name_candidates = + if options[:as] + [options[:as]] + else + active_record_name = active_record.name.demodulize + [active_record_name, ActiveSupport::Inflector.pluralize(active_record_name)] + end + + inverse_name_candidates.map! do |candidate| + ActiveSupport::Inflector.underscore(candidate).to_sym + end + + inverse_name_candidates.detect do |inverse_name| + 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 + + valid_inverse_reflection?(reflection) + end + 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. + def valid_inverse_reflection?(reflection) + reflection && + klass <= reflection.active_record && + 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>: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 + end + + class HasManyReflection < AssociationReflection # :nodoc: + def macro; :has_many; end + + def collection?; true; end + + def association_class + if options[:through] + Associations::HasManyThroughAssociation + else + Associations::HasManyAssociation + end + end + + def association_primary_key(klass = nil) + primary_key(klass || self.klass) + end + end + + class HasOneReflection < AssociationReflection # :nodoc: + def macro; :has_one; end + + def has_one?; true; end + + def association_class + if options[:through] + Associations::HasOneThroughAssociation + else + Associations::HasOneAssociation + end + end + + private + + def calculate_constructable(macro, options) + !options[:through] + end + end + + class BelongsToReflection < AssociationReflection # :nodoc: + def macro; :belongs_to; end + + def belongs_to?; true; end + + def association_class + if polymorphic? + Associations::BelongsToPolymorphicAssociation + else + Associations::BelongsToAssociation + end + end + + def join_primary_key(klass = nil) + polymorphic? ? association_primary_key(klass) : association_primary_key + end + + def join_foreign_key + foreign_key + end + + private + def can_find_inverse_of_automatically?(_) + !polymorphic? && super + end + + def calculate_constructable(macro, options) + !polymorphic? + end + end + + class HasAndBelongsToManyReflection < AssociationReflection # :nodoc: + def macro; :has_and_belongs_to_many; end + + def collection? + true + end + end + + # Holds all the metadata about a :through association as it was specified + # in the Active Record class. + class ThroughReflection < AbstractReflection #:nodoc: + delegate :foreign_key, :foreign_type, :association_foreign_key, :join_id_for, + :active_record_primary_key, :type, :get_join_keys, 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 through_reflection? + true + 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 collect_join_chain + collect_join_reflections [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: + delegate_reflection.clear_association_scope_cache + source_reflection.clear_association_scope_cache + through_reflection.clear_association_scope_cache + end + + def scopes + source_reflection.scopes + super + end + + def join_scopes(table, predicate_builder) # :nodoc: + source_reflection.join_scopes(table, predicate_builder) + super + end + + def has_scope? + scope || options[:source_type] || + source_reflection.has_scope? || + through_reflection.has_scope? + end + + # A through association is nested if there would be more than one join table + def nested? + source_reflection.through_reflection? || through_reflection.through_reflection? + 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 + raise AmbiguousSourceReflectionForThroughAssociation.new( + active_record.name, + macro, + name, + options, + source_reflection_names + ) + 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? + 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 + + if parent_reflection.nil? + reflections = active_record.reflections.keys.map(&:to_sym) + + if reflections.index(through_reflection.name) > reflections.index(name) + raise HasManyThroughOrderError.new(active_record.name, self, through_reflection) + end + end + + check_validity_of_inverse! + end + + def constraints + scope_chain = source_reflection.constraints + scope_chain << scope if scope + scope_chain + end + + def add_as_source(seed) + collect_join_reflections seed + end + + def add_as_polymorphic_through(reflection, seed) + collect_join_reflections(seed + [PolymorphicReflection.new(self, reflection)]) + end + + def add_as_through(seed) + collect_join_reflections(seed + [self]) + end + + protected + def actual_source_reflection # FIXME: this is a horrible name + source_reflection.actual_source_reflection + end + + private + attr_reader :delegate_reflection + + def collect_join_reflections(seed) + a = source_reflection.add_as_source seed + if options[:source_type] + through_reflection.add_as_polymorphic_through self, a + else + through_reflection.add_as_through a + end + end + + def inverse_name; delegate_reflection.send(:inverse_name); end + + 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 < AbstractReflection # :nodoc: + delegate :klass, :scope, :plural_name, :type, :get_join_keys, :scope_for, to: :@reflection + + def initialize(reflection, previous_reflection) + @reflection = reflection + @previous_reflection = previous_reflection + end + + def join_scopes(table, predicate_builder) # :nodoc: + scopes = @previous_reflection.join_scopes(table, predicate_builder) + super + scopes << build_scope(table, predicate_builder).instance_exec(nil, &source_type_scope) + end + + def constraints + @reflection.constraints + [source_type_scope] + end + + private + def source_type_scope + type = @previous_reflection.foreign_type + source_type = @previous_reflection.options[:source_type] + lambda { |object| where(type => source_type) } + end + end + + class RuntimeReflection < AbstractReflection # :nodoc: + delegate :scope, :type, :constraints, :get_join_keys, to: :@reflection + + def initialize(reflection, association) + @reflection = reflection + @association = association + end + + def klass + @association.klass + end + + def aliased_table + @aliased_table ||= Arel::Table.new(table_name, type_caster: klass.type_caster) + end + + def all_includes; yield; end + end + end +end |