Return a null column from `column_for_attribute` when no column exists.

This reverts commit ae96f229f6501d8635811d6b22d75d43cdb880a4.

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/lib/active_record/attribute_methods.rb

1 files changed, 6 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/column.rb b/activerecord/lib/active_record/connection_adapters/column.rb
index 65d8b1a8ab..d7f999c3c6 100644
--- a/activerecord/lib/active_record/connection_adapters/column.rb
+++ b/activerecord/lib/active_record/connection_adapters/column.rb
@@ -77,6 +77,12 @@ module ActiveRecord
         [self.class, name, default, cast_type, sql_type, null, default_function]
       end
     end
+
+    class NullColumn < Column
+      def initialize(name)
+        super name, nil, Type::Value.new
+      end
+    end
   end
   # :startdoc:
 end