atk4\data\Model::loaded PHP Method

    public function loaded()
    {
        return $this->id !== null;
    }

 public function testDoubleJoin()
 {
     $a = ['user' => [10 => ['id' => 10, 'name' => 'John 2', 'contact_id' => 100], 20 => ['id' => 20, 'name' => 'Peter', 'contact_id' => 100], 30 => ['id' => 30, 'name' => 'XX', 'contact_id' => 200], 40 => ['id' => 40, 'name' => 'YYY', 'contact_id' => 300]], 'contact' => [100 => ['id' => 100, 'contact_phone' => '+555', 'country_id' => 1], 200 => ['id' => 200, 'contact_phone' => '+999', 'country_id' => 2], 300 => ['id' => 300, 'contact_phone' => '+777', 'country_id' => 5]], 'country' => [1 => ['id' => 1, 'name' => 'UK'], 2 => ['id' => 2, 'name' => 'US'], 3 => ['id' => 3, 'name' => 'India']]];
     $this->setDB($a);
     $db = new Persistence_SQL($this->db->connection);
     $m_u = new Model($db, 'user');
     $m_u->addField('contact_id');
     $m_u->addField('name');
     $j_contact = $m_u->join('contact');
     $j_contact->addField('contact_phone');
     $j_country = $j_contact->join('country');
     $j_country->addField('country_name', ['actual' => 'name']);
     $m_u->load(10);
     $m_u->delete();
     $m_u->loadBy('country_name', 'US');
     $this->assertEquals(30, $m_u->id);
     $m_u['country_name'] = 'USA';
     $m_u->save();
     $m_u->tryLoad(40);
     $this->assertEquals(false, $m_u->loaded());
     $this->assertSame($m_u->getElement('country_id')->join, $m_u->getElement('contact_phone')->join);
     $m_u->unload();
     $m_u->save(['name' => 'new', 'contact_phone' => '+000', 'country_name' => 'LV']);
     $this->assertEquals(['user' => [20 => ['id' => 20, 'name' => 'Peter', 'contact_id' => 100], 30 => ['id' => 30, 'name' => 'XX', 'contact_id' => 200], 40 => ['id' => 40, 'name' => 'YYY', 'contact_id' => 300], 41 => ['id' => 41, 'name' => 'new', 'contact_id' => 301]], 'contact' => [200 => ['id' => 200, 'contact_phone' => '+999', 'country_id' => 2], 300 => ['id' => 300, 'contact_phone' => '+777', 'country_id' => 5], 301 => ['id' => 301, 'contact_phone' => '+000', 'country_id' => 4]], 'country' => [2 => ['id' => 2, 'name' => 'USA'], 3 => ['id' => 3, 'name' => 'India'], 4 => ['id' => 4, 'name' => 'LV']]], $this->getDB());
 }