dm-sql-finders

https://github.com/d11wtq/dm-sql-finders

dm-sql-finders add #by_sql to your DataMapper models and provides a clean mechanism for using the names of the properties in your model, instead of the actual fields in the database. Any SQL is supported and actual DataMapper Query objects wrap the SQL, thus delaying its execution until a kicker method materializes the records for the query. \ You can also chain standard DataMapper query methods onto the #by_sql call to refine the query.