DMZ 1.7.1 (DataMapper OverZealous Edition)

[eluser]OverZealous[/eluser]
@BRK Network

Your relationships look something like this:

Code:

User
  fields: firstname, lastname, etc
  has_one
     city
     group
  has_many
     district
     userlesson

UserLesson
  fields: priority, price, etc
  has_one
    lesson
    experience_year

Lesson
  fields: name, etc
  has_many
    userlesson

(Group, city, etc, will need has_many relationships back to user, etc.)

Tables:

Code:

users
   id, firstname, lastname, city_id, group_id

userlessons
   id, lesson_id, experienceyear_id

userlessons_users // note alphabetical order, it's important!
   id, userlesson_id, user_id

lessons
   id, name

group
   name

etc.

Basically what I've done is created a new object, UserLesson, which ties users to lessons. It allows you to do all kinds of cool queries, like this:

Code:

$user = new User($login_id);
// get all of a user's lessons
$user->userlesson
    ->include_related('lesson', '*', TRUE, TRUE)
    ->include_related('experienceyear', '*', TRUE, TRUE)
    ->get_iterated();

// get all of a user's Math lessons
$user->userlesson
    ->include_related('lesson', '*', TRUE, TRUE)
    ->include_related('experienceyear', '*', TRUE, TRUE)
    ->where_related('lesson', 'name', 'Math')
    ->get_iterated();

// get all math or biology lessons, and the users associated with them
$userlessons = new UserLesson();
$userlessons
    ->include_related('user', array('firstname','lastname'))
    ->include_related('lesson', 'name')
    ->where_in_related('lesson', 'name', array('Math', 'Biology'))
    ->order_by_related('lesson', 'name')
    ->get_paged_iterated($page, 20);

foreach($userlessons as $userlesson) {
    echo($userlesson->lesson_name .
           ' is taught by ' . $userlesson->user_firstname . ' ' . $userlesson->user_lastname .
           '<br/>');
}

Hopefully that will give you some starting points.