What I am looking for is a tool or better a PHP class, which lets me do something like this - only for rapid prototyping ideas to get fast results:

All I have is an class diagramm UML conform.

An I want to declare these classes in a way like:

class Task extends RadidPrototypingORM {

var task_id = array(
is_key => true,
);

public function user() {
return belongsTo();
}

public function sub_tasks() {
return hasManyAggregate();
}

}

etc. pp.

This is a bit like the Eloquent ORM from Laravel, but the model descriptions should contain everything to build the database automagically.