atk4\data\tests\smbo\Document::init PHP Method

    public function init()
    {
        parent::init();
        // Documest is sent from one Contact to Another
        $this->hasOne('contact_from_id', new Contact());
        $this->hasOne('contact_to_id', new Contact());
        $this->addField('doc_type', ['enum' => ['invoice', 'payment']]);
        $this->addField('amount', ['type' => 'money']);
    }