From d4f21c75e65ecef6c08034c22e5c0a6451a9a030 Mon Sep 17 00:00:00 2001
From: Hongli Lai (Phusion) <hongli@phusion.nl>
Date: Sun, 21 Sep 2008 23:51:02 +0200
Subject: [PATCH] Add an 'extra_conditions' parameter to configure_dependency_for_has_many for
 supporting certain plugins, and make the generated callbacks open a
 transaction.

---
 activerecord/lib/active_record/associations.rb |   31 +++++++++++++++++++++--
 1 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 3cad914..6442803 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1428,17 +1428,28 @@ module ActiveRecord
           []
         end
 
+        # Creates before_destroy callback methods that nullify, delete or destroy
+        # has_many associated objects, according to the defined :dependent rule.
+        #
         # See HasManyAssociation#delete_records.  Dependent associations
         # delete children, otherwise foreign key is set to NULL.
-        def configure_dependency_for_has_many(reflection)
+        #
+        # The +extra_conditions+ parameter, which is not used within the main
+        # Active Record codebase, is meant to allow plugins to define extra
+        # finder conditions.
+        def configure_dependency_for_has_many(reflection, extra_conditions = nil)
           if reflection.options.include?(:dependent)
             # Add polymorphic type if the :as option is present
             dependent_conditions = []
             dependent_conditions << "#{reflection.primary_key_name} = \#{record.quoted_id}"
             dependent_conditions << "#{reflection.options[:as]}_type = '#{base_class.name}'" if reflection.options[:as]
             dependent_conditions << sanitize_sql(reflection.options[:conditions]) if reflection.options[:conditions]
+            dependent_conditions << extra_conditions if extra_conditions
             dependent_conditions = dependent_conditions.collect {|where| "(#{where})" }.join(" AND ")
 
+            # Note: the use of transactions in the generated callback methods
+            # are intentional: it allows plugins to hook into the behavior.
+            
             case reflection.options[:dependent]
               when :destroy
                 method_name = "has_many_dependent_destroy_for_#{reflection.name}".to_sym
@@ -1447,9 +1458,23 @@ module ActiveRecord
                 end
                 before_destroy method_name
               when :delete_all
-                module_eval "before_destroy { |record| #{reflection.class_name}.delete_all(%(#{dependent_conditions})) }"
+                module_eval %Q{
+                  before_destroy do |record|
+                    record.#{reflection.name}.transaction do
+                      #{reflection.class_name}.delete_all("#{dependent_conditions}")
+                    end
+                  end
+                }
               when :nullify
-                module_eval "before_destroy { |record| #{reflection.class_name}.update_all(%(#{reflection.primary_key_name} = NULL),  %(#{dependent_conditions})) }"
+                module_eval %Q{
+                  before_destroy do |record|
+                    record.#{reflection.name}.transaction do
+                      #{reflection.class_name}.update_all(
+                          "#{reflection.primary_key_name} = NULL",
+                          "#{dependent_conditions}")
+                    end
+                  end
+                }
               else
                 raise ArgumentError, "The :dependent option expects either :destroy, :delete_all, or :nullify (#{reflection.options[:dependent].inspect})"
             end
-- 
1.6.0.2