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Merge pull request #9522 from wangjohn/automatic_search_for_associati…

…on_inverses

Finding inverse associations automatically
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2 parents a0f9041 + 26d19b4 commit d156b4724f79d51bb924ccb5055f3602bb7fcc65 @jeremy jeremy committed May 8, 2013
@@ -5,7 +5,7 @@ def macro
end
def valid_options
- super + [:primary_key, :dependent, :as, :through, :source, :source_type, :inverse_of, :counter_cache]
+ super + [:primary_key, :dependent, :as, :through, :source, :source_type, :inverse_of, :automatic_inverse_of, :counter_cache]
end
def valid_dependent_options
@@ -1,7 +1,7 @@
module ActiveRecord::Associations::Builder
class SingularAssociation < Association #:nodoc:
def valid_options
- super + [:remote, :dependent, :counter_cache, :primary_key, :inverse_of]
+ super + [:remote, :dependent, :counter_cache, :primary_key, :inverse_of, :automatic_inverse_of]
end
def constructable?
@@ -305,6 +305,11 @@ def accepts_nested_attributes_for(*attr_names)
reflection.options[:autosave] = true
add_autosave_association_callbacks(reflection)
+ # Clear cached values of any inverse associations found in the
+ # reflection and prevent the reflection from finding inverses
+ # automatically in the future.
+ reflection.remove_automatic_inverse_of!
+
nested_attributes_options = self.nested_attributes_options.dup
nested_attributes_options[association_name.to_sym] = options
self.nested_attributes_options = nested_attributes_options
@@ -181,6 +181,7 @@ def klass
def initialize(*args)
super
@collection = [:has_many, :has_and_belongs_to_many].include?(macro)
+ @automatic_inverse_of = nil
end
# Returns a new, unsaved instance of the associated class. +attributes+ will
@@ -289,15 +290,32 @@ def scope_chain
alias :source_macro :macro
def has_inverse?
- @options[:inverse_of]
+ @options[:inverse_of] || find_inverse_of_automatically
end
def inverse_of
- if has_inverse?
- @inverse_of ||= klass.reflect_on_association(options[:inverse_of])
+ @inverse_of ||= if options[:inverse_of]
+ klass.reflect_on_association(options[:inverse_of])
+ else
+ find_inverse_of_automatically
end
end
+ # Clears the cached value of +@inverse_of+ on this object. This will
+ # not remove the :inverse_of option however, so future calls on the
+ # +inverse_of+ will have to recompute the inverse.
+ def clear_inverse_of_cache!
+ @inverse_of = nil
+ end
+
+ # Removes the cached inverse association that was found automatically
+ # and prevents this object from finding the inverse association
+ # automatically in the future.
+ def remove_automatic_inverse_of!
+ @automatic_inverse_of = nil
+ options[:automatic_inverse_of] = false
+ end
+
def polymorphic_inverse_of(associated_class)
if has_inverse?
if inverse_relationship = associated_class.reflect_on_association(options[:inverse_of])
@@ -366,7 +384,84 @@ def polymorphic?
options.key? :polymorphic
end
+ VALID_AUTOMATIC_INVERSE_MACROS = [:has_many, :has_one, :belongs_to]
+ INVALID_AUTOMATIC_INVERSE_OPTIONS = [:conditions, :through, :polymorphic, :foreign_key]
+
private
+ # Attempts to find the inverse association automatically.
+ # If it cannot find a suitable inverse association, it returns
+ # nil.
+ def find_inverse_of_automatically
+ if @automatic_inverse_of == false
+ nil
+ elsif @automatic_inverse_of.nil?
+ set_automatic_inverse_of
+ else
+ klass.reflect_on_association(@automatic_inverse_of)
+ end
+ end
+
+ # Sets the +@automatic_inverse_of+ instance variable, and returns
+ # either nil or the inverse association that it finds.
+ #
+ # This method caches the inverse association that is found so that
+ # future calls to +find_inverse_of_automatically+ have much less
+ # overhead.
+ def set_automatic_inverse_of
+ if can_find_inverse_of_automatically?(self)
+ inverse_name = active_record.name.downcase.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)
+ @automatic_inverse_of = inverse_name
+ reflection
+ else
+ @automatic_inverse_of = false
+ nil
+ end
+ else
+ @automatic_inverse_of = false
+ nil
+ end
+ end
+
+ # Checks if the inverse reflection that is returned from the
+ # +set_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.try(:name) &&
+ klass.primary_key == reflection.active_record_primary_key &&
+ 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
+ # +automatic_inverse_of+ option cannot be set to false. Second, we must
+ # have :has_many, :has_one, :belongs_to associations. Third, we must
+ # not have options such as :class_name or :polymorphic 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[:automatic_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.camelize
class_name = class_name.singularize if collection?
@@ -5,6 +5,88 @@
require 'models/zine'
require 'models/club'
require 'models/sponsor'
+require 'models/rating'
+require 'models/comment'
+require 'models/car'
+require 'models/bulb'
+
+class AutomaticInverseFindingTests < ActiveRecord::TestCase
+ fixtures :ratings, :comments, :cars
+
+ def test_has_one_and_belongs_to_should_find_inverse_automatically
+ car_reflection = Car.reflect_on_association(:bulb)
+ bulb_reflection = Bulb.reflect_on_association(:car)
+
+ assert_respond_to car_reflection, :has_inverse?
+ assert car_reflection.has_inverse?, "The Car reflection should have an inverse"
+ assert_equal bulb_reflection, car_reflection.inverse_of, "The Car reflection's inverse should be the Bulb reflection"
+
+ assert_respond_to bulb_reflection, :has_inverse?
+ assert bulb_reflection.has_inverse?, "The Bulb reflection should have an inverse"
+ assert_equal car_reflection, bulb_reflection.inverse_of, "The Bulb reflection's inverse should be the Car reflection"
+ end
+
+ def test_has_many_and_belongs_to_should_find_inverse_automatically
+ comment_reflection = Comment.reflect_on_association(:ratings)
+ rating_reflection = Rating.reflect_on_association(:comment)
+
+ assert_respond_to comment_reflection, :has_inverse?
+ assert comment_reflection.has_inverse?, "The Comment reflection should have an inverse"
+ assert_equal rating_reflection, comment_reflection.inverse_of, "The Comment reflection's inverse should be the Rating reflection"
+ end
+
+ def test_has_one_and_belongs_to_automatic_inverse_shares_objects
+ car = Car.first
+ bulb = Bulb.create!(car: car)
+
+ assert_equal car.bulb, bulb, "The Car's bulb should be the original bulb"
+
+ car.bulb.color = "Blue"
+ assert_equal car.bulb.color, bulb.color, "Changing the bulb's color on the car association should change the bulb's color"
+
+ bulb.color = "Red"
+ assert_equal bulb.color, car.bulb.color, "Changing the bulb's color should change the bulb's color on the car association"
+ end
+
+ def test_has_many_and_belongs_to_automatic_inverse_shares_objects_on_rating
+ comment = Comment.first
+ rating = Rating.create!(comment: comment)
+
+ assert_equal rating.comment, comment, "The Rating's comment should be the original Comment"
+
+ rating.comment.body = "Brogramming is the act of programming, like a bro."
+ assert_equal rating.comment.body, comment.body, "Changing the Comment's body on the association should change the original Comment's body"
+
+ comment.body = "Broseiden is the king of the sea of bros."
+ assert_equal comment.body, rating.comment.body, "Changing the original Comment's body should change the Comment's body on the association"
+ end
+
+ def test_has_many_and_belongs_to_automatic_inverse_shares_objects_on_comment
+ rating = Rating.create!
+ comment = Comment.first
+ rating.comment = comment
+
+ assert_equal rating.comment, comment, "The Rating's comment should be the original Comment"
+
+ rating.comment.body = "Brogramming is the act of programming, like a bro."
+ assert_equal rating.comment.body, comment.body, "Changing the Comment's body on the association should change the original Comment's body"
+
+ comment.body = "Broseiden is the king of the sea of bros."
+ assert_equal comment.body, rating.comment.body, "Changing the original Comment's body should change the Comment's body on the association"
+ end
+
+ def test_polymorphic_and_has_many_through_relationships_should_not_have_inverses
+ sponsor_reflection = Sponsor.reflect_on_association(:sponsorable)
+
+ assert_respond_to sponsor_reflection, :has_inverse?
+ assert !sponsor_reflection.has_inverse?, "A polymorphic association should not find an inverse automatically"
+
+ club_reflection = Club.reflect_on_association(:members)
+
+ assert_respond_to club_reflection, :has_inverse?
+ assert !club_reflection.has_inverse?, "A has_many_through association should not find an inverse automatically"
+ end
+end
class InverseAssociationTests < ActiveRecord::TestCase
def test_should_allow_for_inverse_of_options_in_associations
@@ -800,7 +800,9 @@ def test_validate_presence_of_parent_works_with_inverse_of
def test_validate_presence_of_parent_fails_without_inverse_of
Man.accepts_nested_attributes_for(:interests)
Man.reflect_on_association(:interests).options.delete(:inverse_of)
+ Man.reflect_on_association(:interests).clear_inverse_of_cache!
Interest.reflect_on_association(:man).options.delete(:inverse_of)
+ Interest.reflect_on_association(:man).clear_inverse_of_cache!
repair_validations(Interest) do
Interest.validates_presence_of(:man)
@@ -1,6 +1,6 @@
class Club < ActiveRecord::Base
has_one :membership
- has_many :memberships
+ has_many :memberships, :automatic_inverse_of => false
has_many :members, :through => :memberships
has_many :current_memberships
has_one :sponsor
@@ -1,5 +1,5 @@
class Interest < ActiveRecord::Base
- belongs_to :man, :inverse_of => :interests
+ belongs_to :man, :inverse_of => :interests, :automatic_inverse_of => false
belongs_to :polymorphic_man, :polymorphic => true, :inverse_of => :polymorphic_interests
belongs_to :zine, :inverse_of => :interests
end
@@ -1,7 +1,7 @@
class Man < ActiveRecord::Base
has_one :face, :inverse_of => :man
has_one :polymorphic_face, :class_name => 'Face', :as => :polymorphic_man, :inverse_of => :polymorphic_man
- has_many :interests, :inverse_of => :man
+ has_many :interests, :inverse_of => :man, :automatic_inverse_of => false
has_many :polymorphic_interests, :class_name => 'Interest', :as => :polymorphic_man, :inverse_of => :polymorphic_man
# These are "broken" inverse_of associations for the purposes of testing
has_one :dirty_face, :class_name => 'Face', :inverse_of => :dirty_man
@@ -9,7 +9,7 @@ class Member < ActiveRecord::Base
has_one :hairy_club, -> { where :clubs => {:name => "Moustache and Eyebrow Fancier Club"} }, :through => :membership, :source => :club
has_one :sponsor, :as => :sponsorable
has_one :sponsor_club, :through => :sponsor
- has_one :member_detail
+ has_one :member_detail, :automatic_inverse_of => false
has_one :organization, :through => :member_detail
belongs_to :member_type
@@ -1,5 +1,5 @@
class MemberDetail < ActiveRecord::Base
- belongs_to :member
+ belongs_to :member, :automatic_inverse_of => false
belongs_to :organization
has_one :member_type, :through => :member

5 comments on commit d156b47

Owner

rafaelfranca replied May 11, 2013

@wangjohn was the documentation updated?

Contributor

wangjohn replied May 11, 2013

@rafaelfranca No it hasn't. I'll work on documenting it.

Owner

rafaelfranca replied May 11, 2013

Thank you

If I understand this commit correctly, we only need to supply inverse_of if association name can not be inferred directly?

Owner

rafaelfranca replied Jun 14, 2013

Yes

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