diff options
| -rw-r--r-- | activerecord/lib/active_record/associations.rb | 19 |
1 files changed, 7 insertions, 12 deletions
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb index 1ca648d48d..82cb3fed59 100644 --- a/activerecord/lib/active_record/associations.rb +++ b/activerecord/lib/active_record/associations.rb @@ -955,20 +955,16 @@ module ActiveRecord # The +traps+ association on +Dungeon+ and the +dungeon+ association on +Trap+ are # the inverse of each other and the inverse of the +dungeon+ association on +EvilWizard+ # is the +evil_wizard+ association on +Dungeon+ (and vice-versa). By default, - # Active Record doesn't know anything about these inverse relationships and so no object - # loading optimization is possible. For example: + # Active Record can guess the inverse of the association based on the name + # of the class. The result is the following: # # d = Dungeon.first # t = d.traps.first - # d.level == t.dungeon.level # => true - # d.level = 10 - # d.level == t.dungeon.level # => false + # d.object_id == t.dungeon.object_id # => true # # The +Dungeon+ instances +d+ and <tt>t.dungeon</tt> in the above example refer to - # the same object data from the database, but are actually different in-memory copies - # of that data. Specifying the <tt>:inverse_of</tt> option on associations lets you tell - # Active Record about inverse relationships and it will optimise object loading. For - # example, if we changed our model definitions to: + # the same in-memory instance since the association matches the name of the class. + # The result would be the same if we added +:inverse_of+ to our model definitions: # # class Dungeon < ActiveRecord::Base # has_many :traps, inverse_of: :dungeon @@ -983,15 +979,14 @@ module ActiveRecord # belongs_to :dungeon, inverse_of: :evil_wizard # end # - # Then, from our code snippet above, +d+ and <tt>t.dungeon</tt> are actually the same - # in-memory instance and our final <tt>d.level == t.dungeon.level</tt> will return +true+. - # # There are limitations to <tt>:inverse_of</tt> support: # # * does not work with <tt>:through</tt> associations. # * does not work with <tt>:polymorphic</tt> associations. # * for +belongs_to+ associations +has_many+ inverse associations are ignored. # + # For more information, see the documentation for the +:inverse_of+ option. + # # == Deleting from associations # # === Dependent associations |