1 files changed, 57 insertions, 33 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index 36d7f4ad11..a7785f8786 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -5,16 +5,48 @@ module ActiveRecord
 
       # Returns this record's primary key value wrapped in an Array if one is available
       def to_key
-        key = send(self.class.primary_key)
+        key = self.id
         [key] if key
       end
 
+      # Returns the primary key value
+      def id
+        read_attribute(self.class.primary_key)
+      end
+
+      # Sets the primary key value
+      def id=(value)
+        write_attribute(self.class.primary_key, value)
+      end
+
+      # Queries the primary key value
+      def id?
+        query_attribute(self.class.primary_key)
+      end
+
       module ClassMethods
+        def define_method_attribute(attr_name)
+          super
+
+          if attr_name == primary_key && attr_name != 'id'
+            generated_attribute_methods.send(:alias_method, :id, primary_key)
+            generated_external_attribute_methods.module_eval <<-CODE, __FILE__, __LINE__
+              def id(v, attributes, attributes_cache, attr_name)
+                attr_name = '#{primary_key}'
+                send(attr_name, attributes[attr_name], attributes, attributes_cache, attr_name)
+              end
+            CODE
+          end
+        end
+
+        def dangerous_attribute_method?(method_name)
+          super && !['id', 'id=', 'id?'].include?(method_name)
+        end
+
         # Defines the primary key field -- can be overridden in subclasses. Overwriting will negate any effect of the
         # primary_key_prefix_type setting, though.
         def primary_key
-          @primary_key ||= reset_primary_key
-          raise ActiveRecord::UnknownPrimaryKey.new(self) unless @primary_key
+          @primary_key = reset_primary_key unless defined? @primary_key
           @primary_key
         end
 
@@ -24,16 +56,11 @@ module ActiveRecord
         end
 
         def reset_primary_key #:nodoc:
-          key = self == base_class ? get_primary_key(base_class.name) :
-            base_class.primary_key
-
-          set_primary_key(key)
-          key
-        end
-
-        def primary_key? #:nodoc:
-          @primary_key ||= reset_primary_key
-          !@primary_key.nil?
+          if self == base_class
+            self.primary_key = get_primary_key(base_class.name)
+          else
+            self.primary_key = base_class.primary_key
+          end
         end
 
         def get_primary_key(base_name) #:nodoc:
@@ -45,35 +72,32 @@ module ActiveRecord
           when :table_name_with_underscore
             base_name.foreign_key
           else
-            if ActiveRecord::Base != self && connection.table_exists?(table_name)
-              connection.primary_key(table_name)
+            if ActiveRecord::Base != self && table_exists?
+              connection.schema_cache.primary_keys[table_name]
             else
               'id'
             end
           end
         end
 
-        attr_accessor :original_primary_key
-
-        # Attribute writer for the primary key column
-        def primary_key=(value)
-          @quoted_primary_key = nil
-          @primary_key = value
-        end
-
-        # Sets the name of the primary key column to use to the given value,
-        # or (if the value is nil or false) to the value returned by the given
-        # block.
+        # Sets the name of the primary key column.
+        #
+        #   class Project < ActiveRecord::Base
+        #     self.primary_key = "sysid"
+        #   end
+        #
+        # You can also define the primary_key method yourself:
         #
         #   class Project < ActiveRecord::Base
-        #     set_primary_key "sysid"
+        #     def self.primary_key
+        #       "foo_" + super
+        #     end
         #   end
-        def set_primary_key(value = nil, &block)
-          @quoted_primary_key = nil
-          @primary_key ||= ''
-          self.original_primary_key = @primary_key
-          value &&= value.to_s
-          self.primary_key = block_given? ? instance_eval(&block) : value
+        #   Project.primary_key # => "foo_id"
+        def primary_key=(value)
+          @original_primary_key = @primary_key if defined?(@primary_key)
+          @primary_key          = value && value.to_s
+          @quoted_primary_key   = nil
         end
       end
     end