module ActiveRecord #:nodoc:
module Associations #:nodoc:
=begin rdoc
Class methods added to ActiveRecord::Base for setting up polymorphic associations.
== Notes
STI association targets must enumerated and named. For example, if Dog and Cat both inherit from Animal, you still need to say [:dogs, :cats], and not [:animals].
Namespaced models follow the Rails underscore convention. ZooAnimal::Lion becomes :'zoo_animal/lion'.
You do not need to set up any other associations other than for either the regular method or the double. The join associations and all individual and reverse associations are generated for you. However, a join model and table are required.
There is a tentative report that you can make the parent model be its own join model, but this is untested.
=end
module PolymorphicClassMethods
RESERVED_DOUBLES_KEYS = [:conditions, :order, :limit, :offset, :extend, :skip_duplicates,
:join_extend, :dependent, :rename_individual_collections,
:namespace] #:nodoc:
=begin rdoc
This method creates a doubled-sided polymorphic relationship. It must be called on the join model:
class Devouring < ActiveRecord::Base
belongs_to :eater, :polymorphic => true
belongs_to :eaten, :polymorphic => true
acts_as_double_polymorphic_join(
:eaters => [:dogs, :cats],
:eatens => [:cats, :birds]
)
end
The method works by defining one or more special has_many_polymorphs association on every model in the target lists, depending on which side of the association it is on. Double self-references will work.
The two association names and their value arrays are the only required parameters.
== Available options
These options are passed through to targets on both sides of the association. If you want to affect only one side, prepend the key with the name of that side. For example, :eaters_extend.
:dependent:: Accepts :destroy, :nullify, or :delete_all. Controls how the join record gets treated on any association delete (whether from the polymorph or from an individual collection); defaults to :destroy.
:skip_duplicates:: If true, will check to avoid pushing already associated records (but also triggering a database load). Defaults to true.
:rename_individual_collections:: If true, all individual collections are prepended with the polymorph name, and the children's parent collection is appended with "\_of_#{association_name}".
:extend:: One or an array of mixed modules and procs, which are applied to the polymorphic association (usually to define custom methods).
:join_extend:: One or an array of mixed modules and procs, which are applied to the join association.
:conditions:: An array or string of conditions for the SQL WHERE clause.
:order:: A string for the SQL ORDER BY clause.
:limit:: An integer. Affects the polymorphic and individual associations.
:offset:: An integer. Only affects the polymorphic association.
:namespace:: A symbol. Prepended to all the models in the :from and :through keys. This is especially useful for Camping, which namespaces models by default.
=end
def acts_as_double_polymorphic_join options={}, &extension
collections, options = extract_double_collections(options)
# handle the block
options[:extend] = (if options[:extend]
Array(options[:extend]) + [extension]
else
extension
end) if extension
collection_option_keys = make_general_option_keys_specific!(options, collections)
join_name = self.name.tableize.to_sym
collections.each do |association_id, children|
parent_hash_key = (collections.keys - [association_id]).first # parents are the entries in the _other_ children array
begin
parent_foreign_key = self.reflect_on_association(parent_hash_key._singularize).primary_key_name
rescue NoMethodError
raise PolymorphicError, "Couldn't find 'belongs_to' association for :#{parent_hash_key._singularize} in #{self.name}." unless parent_foreign_key
end
parents = collections[parent_hash_key]
conflicts = (children & parents) # set intersection
parents.each do |plural_parent_name|
parent_class = plural_parent_name._as_class
singular_reverse_association_id = parent_hash_key._singularize
internal_options = {
:is_double => true,
:from => children,
:as => singular_reverse_association_id,
:through => join_name.to_sym,
:foreign_key => parent_foreign_key,
:foreign_type_key => parent_foreign_key.to_s.sub(/_id$/, '_type'),
:singular_reverse_association_id => singular_reverse_association_id,
:conflicts => conflicts
}
general_options = Hash[*options._select do |key, value|
collection_option_keys[association_id].include? key and !value.nil?
end.map do |key, value|
[key.to_s[association_id.to_s.length+1..-1].to_sym, value]
end._flatten_once] # rename side-specific options to general names
general_options.each do |key, value|
# avoid clobbering keys that appear in both option sets
if internal_options[key]
general_options[key] = Array(value) + Array(internal_options[key])
end
end
parent_class.send(:has_many_polymorphs, association_id, internal_options.merge(general_options))
if conflicts.include? plural_parent_name
# unify the alternate sides of the conflicting children
(conflicts).each do |method_name|
unless parent_class.instance_methods.include?(method_name)
parent_class.send(:define_method, method_name) do
(self.send("#{singular_reverse_association_id}_#{method_name}") +
self.send("#{association_id._singularize}_#{method_name}")).freeze
end
end
end
# unify the join model... join model is always renamed for doubles, unlike child associations
unless parent_class.instance_methods.include?(join_name)
parent_class.send(:define_method, join_name) do
(self.send("#{join_name}_as_#{singular_reverse_association_id}") +
self.send("#{join_name}_as_#{association_id._singularize}")).freeze
end
end
else
unless parent_class.instance_methods.include?(join_name)
parent_class.send(:alias_method, join_name, "#{join_name}_as_#{singular_reverse_association_id}")
end
end
end
end
end
private
def extract_double_collections(options)
collections = options._select do |key, value|
value.is_a? Array and key.to_s !~ /(#{RESERVED_DOUBLES_KEYS.map(&:to_s).join('|')})$/
end
raise PolymorphicError, "Couldn't understand options in acts_as_double_polymorphic_join. Valid parameters are your two class collections, and then #{RESERVED_DOUBLES_KEYS.inspect[1..-2]}, with optionally your collection names prepended and joined with an underscore." unless collections.size == 2
options = options._select do |key, value|
!collections[key]
end
[collections, options]
end
def make_general_option_keys_specific!(options, collections)
collection_option_keys = Hash[*collections.keys.map do |key|
[key, RESERVED_DOUBLES_KEYS.map{|option| "#{key}_#{option}".to_sym}]
end._flatten_once]
collections.keys.each do |collection|
options.each do |key, value|
next if collection_option_keys.values.flatten.include? key
# shift the general options to the individual sides
collection_key = "#{collection}_#{key}".to_sym
collection_value = options[collection_key]
case key
when :conditions
collection_value, value = sanitize_sql(collection_value), sanitize_sql(value)
options[collection_key] = (collection_value ? "(#{collection_value}) AND (#{value})" : value)
when :order
options[collection_key] = (collection_value ? "#{collection_value}, #{value}" : value)
when :extend, :join_extend
options[collection_key] = Array(collection_value) + Array(value)
else
options[collection_key] ||= value
end
end
end
collection_option_keys
end
public
=begin rdoc
This method createds a single-sided polymorphic relationship.
class Petfood < ActiveRecord::Base
has_many_polymorphs :eaters, :from => [:dogs, :cats, :birds]
end
The only required parameter, aside from the association name, is :from.
The method generates a number of associations aside from the polymorphic one. In this example Petfood also gets dogs, cats, and birds, and Dog, Cat, and Bird get petfoods. (The reverse association to the parents is always plural.)
== Available options
:from:: An array of symbols representing the target models. Required.
:as:: A symbol for the parent's interface in the join--what the parent 'acts as'.
:through:: A symbol representing the class of the join model. Follows Rails defaults if not supplied (the parent and the association names, alphabetized, concatenated with an underscore, and singularized).
:dependent:: Accepts :destroy, :nullify, :delete_all. Controls how the join record gets treated on any associate delete (whether from the polymorph or from an individual collection); defaults to :destroy.
:skip_duplicates:: If true, will check to avoid pushing already associated records (but also triggering a database load). Defaults to true.
:rename_individual_collections:: If true, all individual collections are prepended with the polymorph name, and the children's parent collection is appended with "_of_#{association_name}". For example, zoos becomes zoos_of_animals. This is to help avoid method name collisions in crowded classes.
:extend:: One or an array of mixed modules and procs, which are applied to the polymorphic association (usually to define custom methods).
:join_extend:: One or an array of mixed modules and procs, which are applied to the join association.
:parent_extend:: One or an array of mixed modules and procs, which are applied to the target models' association to the parents.
:conditions:: An array or string of conditions for the SQL WHERE clause.
:parent_conditions:: An array or string of conditions which are applied to the target models' association to the parents.
:order:: A string for the SQL ORDER BY clause.
:parent_order:: A string for the SQL ORDER BY which is applied to the target models' association to the parents.
:group:: An array or string of conditions for the SQL GROUP BY clause. Affects the polymorphic and individual associations.
:limit:: An integer. Affects the polymorphic and individual associations.
:offset:: An integer. Only affects the polymorphic association.
:namespace:: A symbol. Prepended to all the models in the :from and :through keys. This is especially useful for Camping, which namespaces models by default.
:uniq:: If true, the records returned are passed through a pure-Ruby uniq before they are returned. Rarely needed.
:foreign_key:: The column name for the parent's id in the join.
:foreign_type_key:: The column name for the parent's class name in the join, if the parent itself is polymorphic. Rarely needed--if you're thinking about using this, you almost certainly want to use acts_as_double_polymorphic_join() instead.
:polymorphic_key:: The column name for the child's id in the join.
:polymorphic_type_key:: The column name for the child's class name in the join.
If you pass a block, it gets converted to a Proc and added to :extend.
== On condition nullification
When you request an individual association, non-applicable but fully-qualified fields in the polymorphic association's :conditions, :order, and :group options get changed to NULL. For example, if you set :conditions => "dogs.name != 'Spot'", when you request .cats, the conditions string is changed to NULL != 'Spot'.
Be aware, however, that NULL != 'Spot' returns false due to SQL's 3-value logic. Instead, you need to use the :conditions string "dogs.name IS NULL OR dogs.name != 'Spot'" to get the behavior you probably expect for negative matches.
=end
def has_many_polymorphs (association_id, options = {}, &extension)
_logger_debug "associating #{self}.#{association_id}"
reflection = create_has_many_polymorphs_reflection(association_id, options, &extension)
# puts "Created reflection #{reflection.inspect}"
# configure_dependency_for_has_many(reflection)
collection_reader_method(reflection, PolymorphicAssociation)
end
# Composed method that assigns option defaults, builds the reflection object, and sets up all the related associations on the parent, join, and targets.
def create_has_many_polymorphs_reflection(association_id, options, &extension) #:nodoc:
options.assert_valid_keys(
:from,
:as,
:through,
:foreign_key,
:foreign_type_key,
:polymorphic_key, # same as :association_foreign_key
:polymorphic_type_key,
:dependent, # default :destroy, only affects the join table
:skip_duplicates, # default true, only affects the polymorphic collection
:ignore_duplicates, # deprecated
:is_double,
:rename_individual_collections,
:reverse_association_id, # not used
:singular_reverse_association_id,
:conflicts,
:extend,
:join_class_name,
:join_extend,
:parent_extend,
:table_aliases,
:select, # applies to the polymorphic relationship
:conditions, # applies to the polymorphic relationship, the children, and the join
# :include,
:parent_conditions,
:parent_order,
:order, # applies to the polymorphic relationship, the children, and the join
:group, # only applies to the polymorphic relationship and the children
:limit, # only applies to the polymorphic relationship and the children
:offset, # only applies to the polymorphic relationship
:parent_order,
:parent_group,
:parent_limit,
:parent_offset,
# :source,
:namespace,
:uniq, # XXX untested, only applies to the polymorphic relationship
# :finder_sql,
# :counter_sql,
# :before_add,
# :after_add,
# :before_remove,
# :after_remove
:dummy)
# validate against the most frequent configuration mistakes
verify_pluralization_of(association_id)
raise PolymorphicError, ":from option must be an array" unless options[:from].is_a? Array
options[:from].each{|plural| verify_pluralization_of(plural)}
options[:as] ||= self.name.demodulize.underscore.to_sym
options[:conflicts] = Array(options[:conflicts])
options[:foreign_key] ||= "#{options[:as]}_id"
options[:association_foreign_key] =
options[:polymorphic_key] ||= "#{association_id._singularize}_id"
options[:polymorphic_type_key] ||= "#{association_id._singularize}_type"
if options.has_key? :ignore_duplicates
_logger_warn "DEPRECATION WARNING: please use :skip_duplicates instead of :ignore_duplicates"
options[:skip_duplicates] = options[:ignore_duplicates]
end
options[:skip_duplicates] = true unless options.has_key? :skip_duplicates
options[:dependent] = :destroy unless options.has_key? :dependent
options[:conditions] = sanitize_sql(options[:conditions])
# options[:finder_sql] ||= "(options[:polymorphic_key]
options[:through] ||= build_join_table_symbol(association_id, (options[:as]._pluralize or self.table_name))
# set up namespaces if we have a namespace key
# XXX needs test coverage
if options[:namespace]
namespace = options[:namespace].to_s.chomp("/") + "/"
options[:from].map! do |child|
"#{namespace}#{child}".to_sym
end
options[:through] = "#{namespace}#{options[:through]}".to_sym
end
options[:join_class_name] ||= options[:through]._classify
options[:table_aliases] ||= build_table_aliases([options[:through]] + options[:from])
options[:select] ||= build_select(association_id, options[:table_aliases])
options[:through] = "#{options[:through]}_as_#{options[:singular_reverse_association_id]}" if options[:singular_reverse_association_id]
options[:through] = demodulate(options[:through]).to_sym
options[:extend] = spiked_create_extension_module(association_id, Array(options[:extend]) + Array(extension))
options[:join_extend] = spiked_create_extension_module(association_id, Array(options[:join_extend]), "Join")
options[:parent_extend] = spiked_create_extension_module(association_id, Array(options[:parent_extend]), "Parent")
# create the reflection object
returning(create_reflection(:has_many_polymorphs, association_id, options, self)) do |reflection|
if defined? Dependencies and defined? RAILS_ENV and RAILS_ENV == "development"
inject_dependencies(association_id, reflection) if Dependencies.mechanism == :load
end
# set up the other related associations
create_join_association(association_id, reflection)
create_has_many_through_associations_for_parent_to_children(association_id, reflection)
create_has_many_through_associations_for_children_to_parent(association_id, reflection)
end
end
private
# table mapping for use at the instantiation point
def build_table_aliases(from)
# for the targets
returning({}) do |aliases|
from.map(&:to_s).sort.map(&:to_sym).each_with_index do |plural, t_index|
begin
table = plural._as_class.table_name
rescue NameError => e
raise PolymorphicError, "Could not find a valid class for #{plural.inspect}. If it's namespaced, be sure to specify it as :\"module/#{plural}\" instead."
end
plural._as_class.columns.map(&:name).each_with_index do |field, f_index|
aliases["#{table}.#{field}"] = "t#{t_index}_r#{f_index}"
end
end
end
end
def build_select(association_id, aliases)
# instantiate has to know which reflection the results are coming from
(["\'#{self.name}\' AS polymorphic_parent_class",
"\'#{association_id}\' AS polymorphic_association_id"] +
aliases.map do |table, _alias|
"#{table} AS #{_alias}"
end.sort).join(", ")
end
# model caching
def inject_dependencies(association_id, reflection)
_logger_debug "injecting dependencies"
requirements = [self, reflection.klass].map{|klass| [klass, klass.base_class]}.flatten.uniq
(all_classes_for(association_id, reflection) - requirements).each do |target_klass|
Dependencies.inject_dependency(target_klass, *requirements)
end
end
# method sub-builders
def create_join_association(association_id, reflection)
options = {
:foreign_key => reflection.options[:foreign_key],
:dependent => reflection.options[:dependent],
:class_name => reflection.klass.name,
:extend => reflection.options[:join_extend]
# :limit => reflection.options[:limit],
# :offset => reflection.options[:offset],
# :order => devolve(association_id, reflection, reflection.options[:order], reflection.klass, true),
# :conditions => devolve(association_id, reflection, reflection.options[:conditions], reflection.klass, true)
}
if reflection.options[:foreign_type_key]
type_check = "#{reflection.options[:foreign_type_key]} = #{quote_value(self.base_class.name)}"
conjunction = options[:conditions] ? " AND " : nil
options[:conditions] = "#{options[:conditions]}#{conjunction}#{type_check}"
options[:as] = reflection.options[:as]
end
has_many(reflection.options[:through], options)
inject_before_save_into_join_table(association_id, reflection)
end
def inject_before_save_into_join_table(association_id, reflection)
sti_hook = "sti_class_rewrite"
rewrite_procedure = %[self.send(:#{reflection.options[:polymorphic_type_key]}=, self.#{reflection.options[:polymorphic_type_key]}.constantize.base_class.name)]
# XXX should be abstracted?
reflection.klass.class_eval %[
unless instance_methods.include? "before_save_with_#{sti_hook}"
if instance_methods.include? "before_save"
alias_method :before_save_without_#{sti_hook}, :before_save
def before_save_with_#{sti_hook}
before_save_without_#{sti_hook}
#{rewrite_procedure}
end
else
def before_save_with_#{sti_hook}
#{rewrite_procedure}
end
end
alias_method :before_save, :before_save_with_#{sti_hook}
end
]
end
def create_has_many_through_associations_for_children_to_parent(association_id, reflection)
child_pluralization_map(association_id, reflection).each do |plural, singular|
if singular == reflection.options[:as]
raise PolymorphicError, if reflection.options[:is_double]
"You can't give either of the sides in a double-polymorphic join the same name as any of the individual target classes."
else
"You can't have a self-referential polymorphic has_many :through without renaming the non-polymorphic foreign key in the join model."
end
end
parent = self
plural._as_class.instance_eval do
# this shouldn't be called at all during doubles; there is no way to traverse to a double polymorphic parent (XXX is that right?)
unless reflection.options[:is_double] or reflection.options[:conflicts].include? self.name.tableize.to_sym
# the join table
through = "#{reflection.options[:through]}#{'_as_child' if parent == self}".to_sym
has_many(through,
:as => association_id._singularize,
# :source => association_id._singularize,
# :source_type => reflection.options[:polymorphic_type_key],
:class_name => reflection.klass.name,
:dependent => reflection.options[:dependent],
:extend => reflection.options[:join_extend],
# :limit => reflection.options[:limit],
# :offset => reflection.options[:offset],
:order => devolve(association_id, reflection, reflection.options[:parent_order], reflection.klass),
:conditions => devolve(association_id, reflection, reflection.options[:parent_conditions], reflection.klass)
)
# the association to the target's parents
association = "#{reflection.options[:as]._pluralize}#{"_of_#{association_id}" if reflection.options[:rename_individual_collections]}".to_sym
has_many(association,
:through => through,
:class_name => parent.name,
:source => reflection.options[:as],
:foreign_key => reflection.options[:foreign_key],
:extend => reflection.options[:parent_extend],
:conditions => reflection.options[:parent_conditions],
:order => reflection.options[:parent_order],
:offset => reflection.options[:parent_offset],
:limit => reflection.options[:parent_limit],
:group => reflection.options[:parent_group])
# debugger if association == :parents
#
# nil
end
end
end
end
def create_has_many_through_associations_for_parent_to_children(association_id, reflection)
child_pluralization_map(association_id, reflection).each do |plural, singular|
#puts ":source => #{child}"
current_association = demodulate(child_association_map(association_id, reflection)[plural])
source = demodulate(singular)
if reflection.options[:conflicts].include? plural
# XXX check this
current_association = "#{association_id._singularize}_#{current_association}" if reflection.options[:conflicts].include? self.name.tableize.to_sym
source = "#{source}_as_#{association_id._singularize}".to_sym
end
# make push/delete accessible from the individual collections but still operate via the general collection
extension_module = self.class_eval %[
module #{self.name + current_association._classify + "PolymorphicChildAssociationExtension"}
def push *args; proxy_owner.send(:#{association_id}).send(:push, *args); self; end
alias :<< :push
def delete *args; proxy_owner.send(:#{association_id}).send(:delete, *args); end
def clear; proxy_owner.send(:#{association_id}).send(:clear, #{singular._classify}); end
self
end]
has_many(current_association.to_sym,
:through => reflection.options[:through],
:source => association_id._singularize,
:source_type => plural._as_class.base_class.name,
:class_name => plural._as_class.name, # make STI not conflate subtypes
:extend => (Array(extension_module) + reflection.options[:extend]),
:limit => reflection.options[:limit],
# :offset => reflection.options[:offset],
:order => devolve(association_id, reflection, reflection.options[:order], plural._as_class),
:conditions => devolve(association_id, reflection, reflection.options[:conditions], plural._as_class),
:group => devolve(association_id, reflection, reflection.options[:group], plural._as_class)
)
end
end
# some support methods
def child_pluralization_map(association_id, reflection)
Hash[*reflection.options[:from].map do |plural|
[plural, plural._singularize]
end.flatten]
end
def child_association_map(association_id, reflection)
Hash[*reflection.options[:from].map do |plural|
[plural, "#{association_id._singularize.to_s + "_" if reflection.options[:rename_individual_collections]}#{plural}".to_sym]
end.flatten]
end
def demodulate(s)
s.to_s.gsub('/', '_').to_sym
end
def build_join_table_symbol(association_id, name)
[name.to_s, association_id.to_s].sort.join("_").to_sym
end
def all_classes_for(association_id, reflection)
klasses = [self, reflection.klass, *child_pluralization_map(association_id, reflection).keys.map(&:_as_class)]
klasses += klasses.map(&:base_class)
klasses.uniq
end
def devolve(association_id, reflection, string, klass, remove_inappropriate_clauses = false)
# XXX remove_inappropriate_clauses is not implemented; we'll wait until someone actually needs it
return unless string
string = string.dup
# _logger_debug "devolving #{string} for #{klass}"
inappropriate_classes = (all_classes_for(association_id, reflection) - # the join class must always be preserved
[klass, klass.base_class, reflection.klass, reflection.klass.base_class])
inappropriate_classes.map do |klass|
klass.columns.map do |column|
[klass.table_name, column.name]
end.map do |table, column|
["#{table}.#{column}", "`#{table}`.#{column}", "#{table}.`#{column}`", "`#{table}`.`#{column}`"]
end
end.flatten.sort_by(&:size).reverse.each do |quoted_reference|
# _logger_debug "devolved #{quoted_reference} to NULL"
# XXX clause removal would go here
string.gsub!(quoted_reference, "NULL")
end
# _logger_debug "altered to #{string}"
string
end
def verify_pluralization_of(sym)
sym = sym.to_s
singular = sym.singularize
plural = singular.pluralize
raise PolymorphicError, "Pluralization rules not set up correctly. You passed :#{sym}, which singularizes to :#{singular}, but that pluralizes to :#{plural}, which is different. Maybe you meant :#{plural} to begin with?" unless sym == plural
end
def spiked_create_extension_module(association_id, extensions, identifier = nil)
module_extensions = extensions.select{|e| e.is_a? Module}
proc_extensions = extensions.select{|e| e.is_a? Proc }
# support namespaced anonymous blocks as well as multiple procs
proc_extensions.each_with_index do |proc_extension, index|
module_name = "#{self.to_s}#{association_id._classify}Polymorphic#{identifier}AssociationExtension#{index}"
the_module = self.class_eval "module #{module_name}; self; end" # XXX hrm
the_module.class_eval &proc_extension
module_extensions << the_module
end
module_extensions
end
end
end
end