Added destruction of dependent objects in has_one associations when a new assignment happens #742 [mindel]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@843 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

5 files changed, 29 insertions, 4 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index d17ff99f54..63daed1433 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,19 @@
 *SVN*
 
+* Added destruction of dependent objects in has_one associations when a new assignment happens #742 [mindel]. Example:
+
+    class Account < ActiveRecord::Base
+      has_one :credit_card, :dependent => true
+    end
+    class CreditCard < ActiveRecord::Base
+      belongs_to :account
+    end
+
+    account.credit_card # => returns existing credit card, lets say id = 12
+    account.credit_card = CreditCard.create("number" => "123")
+    account.save # => CC with id = 12 is destroyed
+
+
 * Added validates_numericality_of #716 [skanthak/c.r.mcgrath]. Docuemntation:
 
     Validates whether the value of the specified attribute is numeric by trying to convert it to
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 381f3e4931..229cfb5cfa 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -270,7 +270,8 @@ module ActiveRecord
       #   sql fragment, such as "rank = 5".
       # * <tt>:order</tt>       - specify the order from which the associated object will be picked at the top. Specified as
       #    an "ORDER BY" sql fragment, such as "last_name, first_name DESC"
-      # * <tt>:dependent</tt>   - if set to true the associated object is destroyed alongside this object
+      # * <tt>:dependent</tt>   - if set to true, the associated object is destroyed when this object is. It's also destroyed if another
+      #   association is assigned.
       # * <tt>:foreign_key</tt> - specify the foreign key used for the association. By default this is guessed to be the name
       #   of this class in lower-case and "_id" suffixed. So a +Person+ class that makes a has_one association will use "person_id"
       #   as the default foreign_key.
diff --git a/activerecord/lib/active_record/associations/association_proxy.rb b/activerecord/lib/active_record/associations/association_proxy.rb
index 009e2ec4c2..91da7dec4d 100644
--- a/activerecord/lib/active_record/associations/association_proxy.rb
+++ b/activerecord/lib/active_record/associations/association_proxy.rb
@@ -34,6 +34,10 @@ module ActiveRecord
       end
 
       protected
+        def dependent?
+          @options[:dependent] || false
+        end
+        
         def quoted_record_ids(records)
           records.map { |record| record.quoted_id }.join(',')
         end
diff --git a/activerecord/lib/active_record/associations/has_one_association.rb b/activerecord/lib/active_record/associations/has_one_association.rb
index 30704b6f7e..e566089013 100644
--- a/activerecord/lib/active_record/associations/has_one_association.rb
+++ b/activerecord/lib/active_record/associations/has_one_association.rb
@@ -10,8 +10,13 @@ module ActiveRecord
       def replace(obj, dont_save = false)
         load_target
         unless @target.nil?
-          @target[@association_class_primary_key_name] = nil
-          @target.save unless @owner.new_record?
+          if dependent? && !dont_save     
+            @target.destroy unless @target.new_record?
+            @owner.clear_association_cache
+          else
+            @target[@association_class_primary_key_name] = nil
+            @target.save unless @owner.new_record?
+          end
         end
 
         if obj.nil?
diff --git a/activerecord/test/associations_test.rb b/activerecord/test/associations_test.rb
index 4a2779227d..b35aadf4ff 100755
--- a/activerecord/test/associations_test.rb
+++ b/activerecord/test/associations_test.rb
@@ -94,7 +94,8 @@ class HasOneAssociationsTest < Test::Unit::TestCase
     @signals37.account = nil
     @signals37.save
     assert_nil @signals37.account
-    assert_nil Account.find(old_account_id).firm_id
+    # account is dependent, therefore is destroyed when reference to owner is lost
+    assert_raises(ActiveRecord::RecordNotFound) { Account.find(old_account_id) } 
   end
 
   def test_dependence