fetch_related_records.php

//app/controllers/UserController.php
{
    $user = User::findFirst(7);
     
    print_r($user->getPosts()); //user posts
    print_r($user->getPosts()[0]->getPostTags()); //tags related to particular post
}

get_record.php

//app/controllers/UserController.php
{
    //By its integer primary key
    $user = User::findFirst(7)
 
    //By other primary key
    $user = User::findFirst("code=7");
}

{
    $this->db->query('SELECT * FROM users WHERE id=?', array(7));  
}

pretty_urls.php

//app/routes.php
$router = new \Phalcon\Mvc\Router();
     
$router->add("/people", "Users::index");
$router->add("/guy/{email}", "Users::view");

$router->handle();

save_related.php

//app/controllers/PostController.php

use Phalcon\Mvc\Model\Transaction\Failed as TransactionFailed;

class PostController extends Phalcon\Mvc\Controller
{

    public function addAction()
    {
        if ($this->request->isPost()) {

            try {

                $transaction = $this->transactionManager->get();

                $post = new Post;
                $post->setTransaction($transaction);
                $post->name = $this->request->getPost('name', 'striptags');
                $post->user_id = $this->request->getPost('user_id', 'int');
                $post->content = $this->request->getPost('content');
                if ($post->save() === false){
                    $transaction->rollback("Error saving a record, sorry");
                }

                foreach($this->request->getPost('tag_id') as $tagId){
                    $tag = new PostTags;
                    $tag->setTransaction($transaction);
                    $tag->post_id = $post->id;
                    $tag->tag_id = $tagId;
                    if (false == $tag->save()){
                        $transaction->rollback('Cannot save tag #' . $tag_id);
                    }
                }
            }
         
            $transaction->commit();

            } catch(TransactionFailed $e){
                echo $e->getMessage();
            }
        }
         
        $this->view->setVar('tags', Tag::find());
        $this->view->setVar('users', User::find());
    }

}

to_show_sql_log.php

$eventsManager  = new \Phalcon\Events\Manager();

$di->set('db', function() use ($config, $eventsManager){

	$eventManager->attach('db', function($event, $connection) {
		if ($event->getType() == 'afterQuery') {
			echo $connection->getSQLStatement();
		}
	});

	$connection = new \Phalcon\Db\Adapter\Pdo\Mysql(array(
		"host" => $config->database->host,
		"username" => $config->database->username,
		"password" => $config->database->password,
		"dbname" => $config->database->name
	));

	$connection->setEventsManager($eventsManager);
	
	return $connection;
});

validate_model.php

use Phalcon\Mvc\Model\Validator\Uniqueness;
use Phalcon\Mvc\Model\Validator\Email as EmailValidator;

class Users extends Phalcon\Mvc\Model
{
	public function validation()
	{
		$this->validate(new Uniqueness(array(
			"field" => "email",
			"message" => "This email is already used."
                )));

		$this->validate(new EmailValidator(array(
			'field' => 'email',
			"message" => "Enter a valid email."
		)));

		return $this->validationHasFailed() != true;
	}
}