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-rw-r--r--activerecord/lib/active_record/associations.rb21
-rw-r--r--activerecord/lib/active_record/reflection.rb2
2 files changed, 22 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 5e5995f566..b71200cd2a 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -568,6 +568,8 @@ module ActiveRecord
# @group.avatars << Avatar.new # this would work if User belonged_to Avatar rather than the other way around
# @group.avatars.delete(@group.avatars.last) # so would this
#
+ # == Setting Inverses
+ #
# If you are using a +belongs_to+ on the join model, it is a good idea to set the
# <tt>:inverse_of</tt> option on the +belongs_to+, which will mean that the following example
# works correctly (where <tt>tags</tt> is a +has_many+ <tt>:through</tt> association):
@@ -584,6 +586,25 @@ module ActiveRecord
# belongs_to :tag, inverse_of: :taggings
# end
#
+ # If you do not set the +:inverse_of+ record, the association will do its
+ # best to match itself up with the correct inverse. Automatic +:inverse_of+
+ # detection only works on :has_many, :has_one, and :belongs_to associations.
+ #
+ # Extra options on the associations, as defined in the
+ # +AssociationReflection::INVALID_AUTOMATIC_INVERSE_OPTIONS+ constant, will
+ # also prevent the association's inverse from being found automatically.
+ #
+ # The automatic guessing of the inverse association uses a heuristic based
+ # on the name of the class, so it may not work for all associations,
+ # especially the ones with non-standard names.
+ #
+ # You can turn off the automatic detection of inverse associations by setting
+ # the +:automatic_inverse_of+ option to +false+ like so:
+ #
+ # class Taggable < ActiveRecord::Base
+ # belongs_to :tag, automatic_inverse_of: false
+ # end
+ #
# == Nested Associations
#
# You can actually specify *any* association with the <tt>:through</tt> option, including an
diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb
index 0ba860a186..d922e23e39 100644
--- a/activerecord/lib/active_record/reflection.rb
+++ b/activerecord/lib/active_record/reflection.rb
@@ -450,7 +450,7 @@ module ActiveRecord
# 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
+ # not have options such as :polymorphic or :foreign_key which prevent us
# from correctly guessing the inverse association.
#
# Anything with a scope can additionally ruin our attempt at finding an