Set field encoding to client_encoding for mysql adapter.

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -469,7 +469,8 @@ def columns(table_name)#:nodoc:
         sql = "SHOW FULL FIELDS FROM #{quote_table_name(table_name)}"
         execute_and_free(sql, 'SCHEMA') do |result|
           each_hash(result).map do |field|
-            new_column(field[:Field], field[:Default], field[:Type], field[:Null] == "YES", field[:Collation], field[:Extra])
+            field_name = set_field_encoding(field[:Field])
+            new_column(field_name, field[:Default], field[:Type], field[:Null] == "YES", field[:Collation], field[:Extra])
           end
         end
       end

activerecord/lib/active_record/connection_adapters/mysql2_adapter.rb

@@ -269,6 +269,10 @@ def configure_connection
       def version
         @version ||= @connection.info[:version].scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
       end
+
+      def set_field_encoding field_name
+        field_name
+      end
     end
   end
 end

activerecord/lib/active_record/connection_adapters/mysql_adapter.rb

@@ -559,6 +559,14 @@ def select(sql, name = nil, binds = [])
       def version
         @version ||= @connection.server_info.scan(/^(\d+)\.(\d+)\.(\d+)/).flatten.map { |v| v.to_i }
       end
+
+      def set_field_encoding field_name
+        field_name.force_encoding(client_encoding)
+        if internal_enc = Encoding.default_internal
+          field_name = field_name.encoding(internal_enc)
+        end
+        field_name
+      end
     end
   end
 end

activerecord/test/cases/base_test.rb

@@ -585,8 +585,6 @@ def test_readonly_attributes
   end
 
   def test_unicode_column_name
-    skip "not on mysql" if current_adapter?(:MysqlAdapter)
-    columns = Weird.columns_hash.keys
     weird = Weird.create(:なまえ => 'たこ焼き仮面')
     assert_equal 'たこ焼き仮面', weird.なまえ
   end