1 files changed, 13 insertions, 25 deletions
diff --git a/activerecord/lib/active_record/attribute_methods.rb b/activerecord/lib/active_record/attribute_methods.rb
index cbdd4950a6..e902eb7531 100644
--- a/activerecord/lib/active_record/attribute_methods.rb
+++ b/activerecord/lib/active_record/attribute_methods.rb
@@ -1,7 +1,7 @@
 require 'active_support/core_ext/enumerable'
 require 'active_support/core_ext/string/filters'
 require 'mutex_m'
-require 'concurrent'
+require 'concurrent/map'
 
 module ActiveRecord
   # = Active Record Attribute Methods
@@ -34,30 +34,6 @@ module ActiveRecord
 
     BLACKLISTED_CLASS_METHODS = %w(private public protected allocate new name parent superclass)
 
-    class AttributeMethodCache
-      def initialize
-        @module = Module.new
-        @method_cache = Concurrent::Map.new
-      end
-
-      def [](name)
-        @method_cache.compute_if_absent(name) do
-          safe_name = name.unpack('h*'.freeze).first
-          temp_method = "__temp__#{safe_name}"
-          ActiveRecord::AttributeMethods::AttrNames.set_name_cache safe_name, name
-          @module.module_eval method_body(temp_method, safe_name), __FILE__, __LINE__
-          @module.instance_method temp_method
-        end
-      end
-
-      private
-
-      # Override this method in the subclasses for method body.
-      def method_body(method_name, const_name)
-        raise NotImplementedError, "Subclasses must implement a method_body(method_name, const_name) method."
-      end
-    end
-
     class GeneratedAttributeMethods < Module; end # :nodoc:
 
     module ClassMethods
@@ -191,6 +167,18 @@ module ActiveRecord
           end
       end
 
+      # Returns true if the given attribute exists, otherwise false.
+      #
+      #   class Person < ActiveRecord::Base
+      #   end
+      #
+      #   Person.has_attribute?('name')   # => true
+      #   Person.has_attribute?(:age)     # => true
+      #   Person.has_attribute?(:nothing) # => false
+      def has_attribute?(attr_name)
+        attribute_types.key?(attr_name.to_s)
+      end
+
       # Returns the column object for the named attribute.
       # Returns a +ActiveRecord::ConnectionAdapters::NullColumn+ if the
       # named attribute does not exist.