Question

I have an application that requires:

user owns many projects.
project has one owner.

user works on many projects.
projects have many users.

so I have 3 tables, users, projects_users, projects.
The relationships are:

one user (owner) — many projects (created_by)

many users (id) —- via projects_users (user_id, project_id) —- many projects (id).

In Codeigniter I’ve set up the following relationships in the datamapper models:

Class Project extends DataMapper {

var $has_one = array(
    'created_by' => array(
        'class' => 'user',
        'other_field' => 'owns'
    )
);
var $has_many = array('user' => array(
        'class' => 'user',
        'other_field' => 'project',
        'join_table' => 'projects_users'));

and…

    class User extends DataMapper {

var $has_many = array(
    'project' => array(
        'class' => 'project',
        'other_field' => 'user',
        'join_table' => 'projects_users'
    ),
    'owns' => array(
        'class' => 'project',
        'other_field' => 'created_by'
    )
);

This doesn’t seem to work however and I get a recursive error.
What is the correct way to represent this relationship in datamapper?

Answer 1

Take a look at Multiple Relationships to the Same Model on the doc page: http://datamapper.wanwizard.eu/pages/advancedrelations.html

I’m guessing something like this:

class Project extends DataMapper {
    $has_one = array(
        'owner' => array(
            'class' => 'user',
            'other_field' => 'owned_project'
        )
    );
    $has_many = array(
        'user' => array(
            'class' => 'user',
            'other_field' => 'user_project'
        )
    );
}

class User extends DataMapper {
    $has_many = array(
        'owned_project' => array(
            'class' => 'project',
            'other_field' => 'owner'
        ),
        'user_project' => array(
            'class' => 'project',
            'other_field' => 'user'
        )
    );
}

and you would access like this:

$project = new Project(1); // where "1" is the ID of the project
$owner = $project->owner->get();
$project_users = $project->user->get();

// -------------------------------

$me = new User(1); // where "1" is the ID of the user
$my_projects = $me->owned_project->get();

UPDATE

You will need to update your projects_users join table to this:

projects_users
--------------
user_id
owner_id
owned_project_id
user_project_id

Note that these all match the “keys” that you declared in your $has_one and $has_many arrays. You will not need to update the users or projects tables (the only requirement is that each of them have a primary key field named “id”).