Adds :nullify option to :depends. Closes #2015 (Robby Russell)

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@2595 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activerecord/CHANGELOG

@@ -1,4 +1,7 @@
-*SVN*
+*SVN*                                                                                                                   
+=======
+
+* :dependent now accepts :nullify option. Sets the foreign key of the related objects to NULL instead of deleting them. #2015 [Robby Russell <robby@planetargon.com>] 
 
 * Introduce read-only records.  If you call object.readonly! then it will mark the object as read-only and raise ReadOnlyRecord if you call object.save.  object.readonly? reports whether the object is read-only.  Passing :readonly => true to any finder method will mark returned records as read-only.  The :joins option now implies :readonly, so if you use this option, saving the same record will now fail.  Use find_by_sql to work around.
 

activerecord/lib/active_record/associations.rb

@@ -265,7 +265,9 @@ module ActiveRecord
       # * <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_many association will use "person_id"
       #   as the default foreign_key.
-      # * <tt>:dependent</tt>   - if set to true all the associated object are destroyed alongside this object.
+      # * <tt>:dependent</tt>   - if set to :destroy (or true) all the associated objects are destroyed
+      #   alongside this object. Also accepts :nullify which will set the associated objects foriegn key
+      #   field to NULL.
       #   May not be set if :exclusively_dependent is also set.
       # * <tt>:exclusively_dependent</tt>   - if set to true all the associated object are deleted in one SQL statement without having their
       #   before_destroy callback run. This should only be used on associations that depend solely on this class and don't need to do any
@@ -297,13 +299,22 @@ module ActiveRecord
  
         require_association_class(association_class_name)
 
-        if options[:dependent] and options[:exclusively_dependent]
-          raise ArgumentError, ':dependent and :exclusively_dependent are mutually exclusive options.  You may specify one or the other.' # ' ruby-mode
+        raise ArgumentError, ':dependent and :exclusively_dependent are mutually exclusive options.  You may specify one or the other.' if options[:dependent] and options[:exclusively_dependent]
+          
         # See HasManyAssociation#delete_records.  Dependent associations
         # delete children, otherwise foreign key is set to NULL.
-        elsif options[:dependent]
-          module_eval "before_destroy '#{association_name}.each { |o| o.destroy }'"
-        elsif options[:exclusively_dependent]
+        case options[:dependent]
+          when :destroy, true  
+            module_eval "before_destroy '#{association_name}.each { |o| o.destroy }'"
+          when :nullify
+            module_eval "before_destroy { |record| #{association_class_name}.update_all(%(#{association_class_primary_key_name} = NULL),  %(#{association_class_primary_key_name} = \#{record.quoted_id})) }"
+          when nil, false
+            # pass
+          else
+            raise ArgumentError, 'The :dependent option expects either true, :destroy or :nullify' 
+        end   
+        
+        if options[:exclusively_dependent]
           module_eval "before_destroy { |record| #{association_class_name}.delete_all(%(#{association_class_primary_key_name} = \#{record.quoted_id})) }"
         end
 
@@ -353,7 +364,7 @@ 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 when this object is. It's also destroyed if another
+      # * <tt>:dependent</tt>   - if set to :destroy (or true) all the associated object is destroyed when this object is. Also
       #   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"
@@ -386,7 +397,16 @@ module ActiveRecord
         association_constructor_method(:build, association_name, association_class_name, association_class_primary_key_name, options, HasOneAssociation)
         association_constructor_method(:create, association_name, association_class_name, association_class_primary_key_name, options, HasOneAssociation)
         
-        module_eval "before_destroy '#{association_name}.destroy unless #{association_name}.nil?'" if options[:dependent]
+        case options[:dependent]
+          when :destroy, true
+            module_eval "before_destroy '#{association_name}.destroy unless #{association_name}.nil?'"
+          when :nullify
+            module_eval "before_destroy '#{association_name}.update_attribute(\"#{association_class_primary_key_name}\", nil)'"
+          when nil, false
+            # pass
+          else
+            raise ArgumentError, "The :dependent option expects either :destroy or :nullify."
+        end
 
         # deprecated api
         deprecated_has_association_method(association_name)

activerecord/test/associations_test.rb

@@ -132,10 +132,11 @@ class HasOneAssociationsTest < Test::Unit::TestCase
   end
 
   def test_dependence
+    num_accounts = Account.count
     firm = Firm.find(1)
     assert !firm.account.nil?
-    firm.destroy
-    assert_equal 1, Account.count
+    firm.destroy                
+    assert_equal num_accounts - 1, Account.count
   end
 
   def test_succesful_build_association
@@ -563,7 +564,7 @@ class HasManyAssociationsTest < Test::Unit::TestCase
 
     # Should be destroyed since the association is exclusively dependent.
     assert Client.find_by_id(client_id).nil?
-  end
+  end                                                    
 
   def test_deleting_a_item_which_is_not_in_the_collection
     force_signal37_to_load_all_clients_of_firm
@@ -634,9 +635,26 @@ class HasManyAssociationsTest < Test::Unit::TestCase
   end
 
   def test_dependence_on_account
-    assert_equal 2, Account.count
+    num_accounts = Account.count
     companies(:first_firm).destroy
-    assert_equal 1, Account.count
+    assert_equal num_accounts - 1, Account.count
+  end
+
+
+  def test_depends_and_nullify
+    num_accounts = Account.count
+    num_companies = Company.count
+    
+    core = companies(:rails_core)
+    assert_equal accounts(:rails_core_account), core.account
+    assert_equal [companies(:leetsoft), companies(:jadedpixel)], core.companies
+    core.destroy                                         
+    assert_nil accounts(:rails_core_account).reload.firm_id
+    assert_nil companies(:leetsoft).reload.client_of
+    assert_nil companies(:jadedpixel).reload.client_of
+    
+    
+    assert_equal num_accounts, Account.count
   end
 
   def test_included_in_collection
@@ -658,7 +676,8 @@ class HasManyAssociationsTest < Test::Unit::TestCase
     assert firm.save, "Could not save firm"
     firm.reload
     assert_equal 1, firm.clients.length
-  end
+  end 
+  
   
   def test_replace_with_new
     firm = Firm.find(:first)

activerecord/test/deprecated_associations_test.rb

@@ -79,10 +79,11 @@ class DeprecatedAssociationsTest < Test::Unit::TestCase
   end
 
   def test_has_one_dependence
+    num_accounts = Account.count
     firm = Firm.find(1)
     assert firm.has_account?
-    firm.destroy
-    assert_equal 1, Account.find_all.length
+    firm.destroy            
+    assert_equal num_accounts - 1, Account.count
   end
 
   def test_has_one_dependence_with_missing_association
@@ -124,10 +125,10 @@ class DeprecatedAssociationsTest < Test::Unit::TestCase
     assert !Account.find(2).firm?(companies(:first_firm)), "Unknown isn't linked"
   end
 
-  def test_has_many_dependence_on_account
-    assert_equal 2, Account.find_all.length
+  def test_has_many_dependence_on_account    
+    num_accounts = Account.count
     companies(:first_firm).destroy
-    assert_equal 1, Account.find_all.length
+    assert_equal num_accounts - 1, Account.count
   end
 
   def test_find_in

activerecord/test/fixtures/accounts.yml

@@ -6,3 +6,8 @@ signals37:
 unknown:
   id: 2
   credit_limit: 50
+
+rails_core_account:
+  id: 3
+  firm_id: 6
+  credit_limit: 50

activerecord/test/fixtures/companies.yml

@@ -33,3 +33,15 @@ another_client:
   client_of: 4
   name: Ex Nihilo
   ruby_type: Client
+
+rails_core:
+  id: 6
+  type: DependentFirm
+  
+leetsoft:
+  id: 7
+  client_of: 6
+  
+jadedpixel:
+  id: 8
+  client_of: 6

activerecord/test/fixtures/company.rb

@@ -27,6 +27,12 @@ class Firm < Company
   has_one :account, :foreign_key => "firm_id", :dependent => true
 end
 
+class DependentFirm < Company
+  has_one :account, :foreign_key => "firm_id", :dependent => :nullify
+  has_many :companies, :foreign_key => 'client_of', :order => "id", :dependent => :nullify
+end
+
+
 class Client < Company
   belongs_to :firm, :foreign_key => "client_of"
   belongs_to :firm_with_basic_id, :class_name => "Firm", :foreign_key => "firm_id"
@@ -62,4 +68,4 @@ class Account < ActiveRecord::Base
     def validate
       errors.add_on_empty "credit_limit"
     end
-end
+end

activerecord/test/inheritance_test.rb

@@ -57,7 +57,7 @@ class InheritanceTest < Test::Unit::TestCase
   end
 
   def test_inheritance_condition
-    assert_equal 5, Company.count
+    assert_equal 8, Company.count
     assert_equal 2, Firm.count
     assert_equal 3, Client.count
   end