1 files changed, 51 insertions, 26 deletions

diff --git a/activerecord/lib/active_record/attribute_methods/primary_key.rb b/activerecord/lib/active_record/attribute_methods/primary_key.rb
index 8bd898d126..6eff716703 100644
--- a/activerecord/lib/active_record/attribute_methods/primary_key.rb
+++ b/activerecord/lib/active_record/attribute_methods/primary_key.rb
@@ -3,18 +3,38 @@ module ActiveRecord
     module PrimaryKey
       extend ActiveSupport::Concern
 
-      # Returns this record's primary key value wrapped in an Array or nil if
-      # the record is not persisted? or has just been destroyed.
+      # Returns this record's primary key value wrapped in an Array if one is available
       def to_key
-        key = send(self.class.primary_key)
-        persisted? && key ? [key] : nil
+        key = self.id
+        [key] if key
+      end
+
+      # Returns the primary key value
+      def id
+        read_attribute(self.class.primary_key)
+      end
+      alias _id id
+
+      # 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 dangerous_attribute_method?(method_name)
+          super && !['id', '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
+          @primary_key = reset_primary_key unless defined? @primary_key
+          @primary_key
         end
 
         # Returns a quoted version of the primary key name, used to construct SQL statements.
@@ -23,11 +43,11 @@ 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
+          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:
@@ -47,28 +67,33 @@ module ActiveRecord
           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
+        def original_primary_key #:nodoc:
+          deprecated_original_property_getter :primary_key
         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)
+        #   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
+
+        def set_primary_key(value = nil, &block) #:nodoc:
+          deprecated_property_setter :primary_key, value, block
           @quoted_primary_key = nil
-          @primary_key ||= ''
-          self.original_primary_key = @primary_key
-          value &&= value.to_s
-          connection_pool.primary_keys[table_name] = value
-          self.primary_key = block_given? ? instance_eval(&block) : value
         end
       end
     end