Allow primary_key to be an attribute when the model is a new record

activerecord/lib/active_record/persistence.rb

@@ -282,7 +282,7 @@ def create
     # that instances loaded from the database would.
     def attributes_from_column_definition
       Hash[self.class.columns.map do |column|
-        [column.name, column.default] unless column.name == self.class.primary_key
+        [column.name, column.default]
       end]
     end
   end

activerecord/lib/active_record/transactions.rb

@@ -301,8 +301,8 @@ def with_transaction_returning_status
     # Save the new record state and id of a record so it can be restored later if a transaction fails.
     def remember_transaction_record_state #:nodoc
       @_start_transaction_state ||= {}
+      @_start_transaction_state[:id] = id if has_attribute?(self.class.primary_key)
       unless @_start_transaction_state.include?(:new_record)
-        @_start_transaction_state[:id] = id if has_attribute?(self.class.primary_key)
         @_start_transaction_state[:new_record] = @new_record
       end
       unless @_start_transaction_state.include?(:destroyed)
@@ -329,7 +329,7 @@ def restore_transaction_record_state(force = false) #:nodoc
             @attributes = @attributes.dup if @attributes.frozen?
             @new_record = restore_state[:new_record]
             @destroyed  = restore_state[:destroyed]
-            if restore_state[:id]
+            if restore_state.has_key?(:id)
               self.id = restore_state[:id]
             else
               @attributes.delete(self.class.primary_key)

activerecord/test/cases/attribute_methods_test.rb

@@ -105,7 +105,7 @@ def test_array_content
 
   def test_read_attributes_before_type_cast
     category = Category.new({:name=>"Test categoty", :type => nil})
-    category_attrs = {"name"=>"Test categoty", "type" => nil, "categorizations_count" => nil}
+    category_attrs = {"name"=>"Test categoty", "id" => nil, "type" => nil, "categorizations_count" => nil}
     assert_equal category_attrs , category.attributes_before_type_cast
   end