PHP Mapper pattern for link tables

Question

I'm finally getting my head around using the Mapper design pattern to structure an object oriented system I'm building in PHP.

I have classes like User, and Project, each with corresponding MySQL tables (and Mapper classes eg ProjectMapper, UserMapper)

What I want to know, is how to approach link tables while using this pattern. I have another class Invitation which invites a User to work on a Project. (It's just a standard link table, with a project_id and a user_id).

Say I want to get a Collection of all the users assigned to a particular project, firstly, where should this function go? ProjectMapper class, InvitationMapper class?

And secondly. how can I make this neat and sensible?

Thanks in advance.

Answer 1

Just take a look at this very interesting article - it helped me a lot when I was working on my own model, which should be efficient and easy to use:

http://www.survivethedeepend.com/zendframeworkbook/en/1.0/implementing.the.domain.model.entries.and.authors

The author explains how to build a reliable model in Zend Framework, but you can use his ideas also in other frameworks or just building your own model without any framework.

I recommend you also (if you are working with Zend) to skip the testing parts - the topic itself is very complex and the testing can be done, when you are done with your model.

Building my own model, I modified a few things, so if you will have further questions - you know - don't hesitate to ask them ;)