I'm working on a project where most of the queries are done through the QueryBuilder, what I find quite awful as the team is not quite used to the model relations and find the "find()" method way too basic for what we do. I'm trying to change this mind but it's getting quite hard. Here follows an example of what I'm trying to do, and I'm lost on what's going wrong:

//models/Things.php
class Things extends \Phalcon\Mvc\Model {

    public function initialize() {
        parent::initialize();
        $this->belongsTo('thing_type_id', ThingTypes::class, 'id', ['alias' => 'ThingTypes']);
        $this->belongsTo('thing_group_id', ThingGroups::class, 'id', ['alias' => 'ThingGroups']);
    }

}

//inside ThingEntity.php
$entries = Things::find([
    'conditions' =>
        'invoice_id IS NULL AND '.
        //'ThingGroups.User.UserTypes.name = :type: AND '. //<= extra-cool if this worked
        'ThingGroups.created_on <= :cut:',
    'bind' => [
        //'type' => $type,
        'cut'  => $cutDate
    ]
]);

That code throws me this:

Unknown model or alias 'ThingGroups' (11), when preparing: SELECT [PhalconRest\Models\Things].* FROM [PhalconRest\Models\Things] WHERE invoice_id IS NULL AND ThingGroups.created_on <= :cut: LIMIT :APL0: OFFSET :APL1:

The models are namespaced, that's why there's an alias with the same classname... But I've also tried using ThingGroups::class."created_on" to no avail.

Bonus

I wanted to know if nested relations could work, as in the commented line in the find() call. Is that possible, to make up for nested JOINs?