Data Mapper Pattern

Additionally, sometimes people split the Data Mapper part into the mapping part ("this attribute maps to this column") and a separate service part ("here's how to insert data"), which further separates the concerns.

John Feminella - http://stackoverflow.com/questions/1977120/data-mapper-an-domain-object-should-never-call-its-data-mapper

In the DataMapper pattern you have one domain object that holds all the business logic, for exmaple user.getLinkToProfile() (or something similar) but knows nothing about the database in question, in addition to this you have a mapper-object that is responsible for saving, updating, selecting, etc. user objects from the database which would have UserMapper::find(1), UserMapper.save(user)

thr - http://stackoverflow.com/questions/93773/how-does-the-activerecord-pattern-differ-from-the-domain-object-or-data-mapper-p

 http://blog.steveklabnik.com/posts/2012-05-07-mixins--a-refactoring-anti-pattern discusses use of DataMapper to reduce surface area of ActiveRecord classes. Essentially an ActiveRecord should not have any public methods; properties are set by DataMapper or Repository through its constructor.