1 files changed, 32 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/attribute_methods/deprecated_underscore_read.rb b/activerecord/lib/active_record/attribute_methods/deprecated_underscore_read.rb
new file mode 100644
index 0000000000..0eb0db65b1
--- /dev/null
+++ b/activerecord/lib/active_record/attribute_methods/deprecated_underscore_read.rb
@@ -0,0 +1,32 @@
+require 'active_support/concern'
+require 'active_support/deprecation'
+
+module ActiveRecord
+  module AttributeMethods
+    module DeprecatedUnderscoreRead
+      extend ActiveSupport::Concern
+
+      included do
+        attribute_method_prefix "_"
+      end
+
+      module ClassMethods
+        protected
+
+        def define_method__attribute(attr_name)
+          # Do nothing, let it hit method missing instead.
+        end
+      end
+
+      protected
+
+      def _attribute(attr_name)
+        ActiveSupport::Deprecation.warn(
+          "You have called '_#{attr_name}'. This is deprecated. Please use " \
+          "either '#{attr_name}' or read_attribute('#{attr_name}')."
+        )
+        read_attribute(attr_name)
+      end
+    end
+  end
+end