From 16b129a68ca1770815107a3edb54090282349ba7 Mon Sep 17 00:00:00 2001
From: Jeremy Kemper <jeremy@bitsweat.net>
Date: Sat, 19 Jan 2008 05:30:42 +0000
Subject: belongs_to supports :dependent => :destroy and :delete. Closes
 #10592.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8675 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
---
 activerecord/lib/active_record/associations.rb | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

(limited to 'activerecord/lib')

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 4743d3be8f..3692be3aeb 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -792,6 +792,10 @@ module ActiveRecord
       # * <tt>:foreign_key</tt> - specify the foreign key used for the association. By default this is guessed to be the name
       #   of the association with an +_id+ suffix. So a class that defines a +belongs_to :person+ association will use +person_id+ as the default +foreign_key+.
       #   Similarly, +belongs_to :favorite_person, :class_name => "Person"+ will use a foreign key of +favorite_person_id+.
+      # * <tt>:dependent</tt>   - if set to <tt>:destroy</tt>, the associated object is destroyed when this object is. If set to
+      #   <tt>:delete</tt>, the associated object is deleted *without* calling its destroy method. This option should not be specified when
+      #   <tt>belongs_to</tt> is used in conjunction with a <tt>has_many</tt> relationship on another class because of the potential to leave
+      #   orphaned records behind.
       # * <tt>:counter_cache</tt> - caches the number of belonging objects on the associate class through the use of +increment_counter+
       #   and +decrement_counter+. The counter cache is incremented when an object of this class is created and decremented when it's
       #   destroyed. This requires that a column named <tt>#{table_name}_count</tt> (such as +comments_count+ for a belonging +Comment+ class)
@@ -876,6 +880,8 @@ module ActiveRecord
             "#{reflection.class_name}.send(:attr_readonly,\"#{cache_column}\".intern) if defined?(#{reflection.class_name}) && #{reflection.class_name}.respond_to?(:attr_readonly)"
           )
         end
+
+        configure_dependency_for_belongs_to(reflection)
       end
 
       # Associates two classes via an intermediate join table.  Unless the join table is explicitly specified as
@@ -1202,6 +1208,19 @@ module ActiveRecord
           end
         end
 
+        def configure_dependency_for_belongs_to(reflection)
+          if reflection.options.include?(:dependent)
+            case reflection.options[:dependent]
+              when :destroy
+                module_eval "before_destroy '#{reflection.name}.destroy unless #{reflection.name}.nil?'"
+              when :delete
+                module_eval "before_destroy '#{reflection.class_name}.delete(#{reflection.name}.id) unless #{reflection.name}.nil?'"
+              else
+                raise ArgumentError, "The :dependent option expects either :destroy or :delete (#{reflection.options[:dependent].inspect})"
+            end
+          end
+        end
+
         def create_has_many_reflection(association_id, options, &extension)
           options.assert_valid_keys(
             :class_name, :table_name, :foreign_key,
-- 
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