Model Events

Events and Events Manager

Models allow you to implement events that will be thrown while performing an insert/update/delete which can be used to define business rules. The following are the events supported by Phalcon\Mvc\Model and their order of execution:

Implementing Events in the Model’s class

The easier way to make a model react to events is to implement a method with the same name of the event in the model’s class:

<?php
namespace Store\Toys;
use Phalcon\Mvc\Model;
class Robots extends Model
{
    public function beforeValidationOnCreate()
    {
        echo 'This is executed before creating a Robot!';
    }
}

Events can be used to assign values before performing an operation, for example:

<?php
use Phalcon\Mvc\Model;
class Products extends Model
{
    public function beforeCreate()
    {
        // Set the creation date
        $this->created_at = date('Y-m-d H:i:s');
    }
    public function beforeUpdate()
    {
        // Set the modification date
        $this->modified_in = date('Y-m-d H:i:s');
    }
}

Using a custom Events Manager

Additionally, this component is integrated with Phalcon\Events\Manager, this means we can create listeners that run when an event is triggered.

<?php
namespace Store\Toys;
use Phalcon\Mvc\Model;
use Phalcon\Events\Event;
use Phalcon\Events\Manager as EventsManager;
class Robots extends Model
{
    public function initialize()
    {
        $eventsManager = new EventsManager();
        // Attach an anonymous function as a listener for 'model' events
        $eventsManager->attach(
            'model:beforeSave',
            function (Event $event, $robot) {
                if ($robot->name === 'Scooby Doo') {
                    echo "Scooby Doo isn't a robot!";
                    return false;
                }
                return true;
            }
        );
        // Attach the events manager to the event
        $this->setEventsManager($eventsManager);
    }
}

In the example given above, the Events Manager only acts as a bridge between an object and a listener (the anonymous function). Events will be fired to the listener when robots are saved:

<?php
use Store\Toys\Robots;
$robot = new Robots();
$robot->name = 'Scooby Doo';
$robot->year = 1969;
$robot->save();

If we want all objects created in our application use the same EventsManager, then we need to assign it to the Models Manager:

<?php
use Phalcon\Events\Event;
use Phalcon\Events\Manager as EventsManager;
// Registering the modelsManager service
$di->setShared(
    'modelsManager',
    function () {
        $eventsManager = new EventsManager();
        // Attach an anonymous function as a listener for 'model' events
        $eventsManager->attach(
            'model:beforeSave',
            function (Event $event, $model) {
                // Catch events produced by the Robots model
                if (get_class($model) === 'Store\Toys\Robots') {
                    if ($model->name === 'Scooby Doo') {
                        echo "Scooby Doo isn't a robot!";
                        return false;
                    }
                }
                return true;
            }
        );
        // Setting a default EventsManager
        $modelsManager = new ModelsManager();
        $modelsManager->setEventsManager($eventsManager);
        return $modelsManager;
    }
);

If a listener returns false that will stop the operation that is executing currently.

Logging Low-Level SQL Statements

When using high-level abstraction components such as Phalcon\Mvc\Model to access a database, it is difficult to understand which statements are finally sent to the database system. Phalcon\Mvc\Model is supported internally by Phalcon\Db. Phalcon\Logger interacts with Phalcon\Db, providing logging capabilities on the database abstraction layer, thus allowing us to log SQL statements as they happen.

<?php
use Phalcon\Logger;
use Phalcon\Events\Manager;
use Phalcon\Logger\Adapter\File as FileLogger;
use Phalcon\Db\Adapter\Pdo\Mysql as Connection;
$di->set(
    'db',
    function () {
        $eventsManager = new EventsManager();
        $logger = new FileLogger('app/logs/debug.log');
        // Listen all the database events
        $eventsManager->attach(
            'db:beforeQuery',
            function ($event, $connection) use ($logger) {
                $logger->log(
                    $connection->getSQLStatement(),
                    Logger::INFO
                );
            }
        );
        $connection = new Connection(
            [
                'host'     => 'localhost',
                'username' => 'root',
                'password' => 'secret',
                'dbname'   => 'invo',
            ]
        );
        // Assign the eventsManager to the db adapter instance
        $connection->setEventsManager($eventsManager);
        return $connection;
    }
);

As models access the default database connection, all SQL statements that are sent to the database system will be logged in the file:

<?php
use Store\Toys\Robots;
$robot = new Robots();
$robot->name       = 'Robby the Robot';
$robot->created_at = '1956-07-21';
if ($robot->save() === false) {
    echo 'Cannot save robot';
}

As above, the file app/logs/db.log will contain something like this:

[Mon, 30 Apr 12 13:47:18 -0500][DEBUG][Resource Id #77] INSERT INTO robots(name, created_at) VALUES ('Robby the Robot', '1956-07-21')

Profiling SQL Statements

Thanks to Phalcon\Db, the underlying component of Phalcon\Mvc\Model, it’s possible to profile the SQL statements generated by the ORM in order to analyze the performance of database operations. With this you can diagnose performance problems and to discover bottlenecks.

<?php
use Phalcon\Db\Profiler as ProfilerDb;
use Phalcon\Events\Manager as EventsManager;
use Phalcon\Db\Adapter\Pdo\Mysql as MysqlPdo;
$di->set(
    'profiler',
    function () {
        return new ProfilerDb();
    },
    true
);
$di->set(
    'db',
    function () use ($di) {
        $eventsManager = new EventsManager();
        // Get a shared instance of the DbProfiler
        $profiler = $di->getProfiler();
        // Listen all the database events
        $eventsManager->attach(
            'db',
            function ($event, $connection) use ($profiler) {
                if ($event->getType() === 'beforeQuery') {
                    $profiler->startProfile(
                        $connection->getSQLStatement()
                    );
                }
                if ($event->getType() === 'afterQuery') {
                    $profiler->stopProfile();
                }
            }
        );
        $connection = new MysqlPdo(
            [
                'host'     => 'localhost',
                'username' => 'root',
                'password' => 'secret',
                'dbname'   => 'invo',
            ]
        );
        // Assign the eventsManager to the db adapter instance
        $connection->setEventsManager($eventsManager);
        return $connection;
    }
);

Profiling some queries:

<?php
use Store\Toys\Robots;
// Send some SQL statements to the database
Robots::find();
Robots::find(
    [
        'order' => 'name',
    ]
);
Robots::find(
    [
        'limit' => 30,
    ]
);
// Get the generated profiles from the profiler
$profiles = $di->get('profiler')->getProfiles();
foreach ($profiles as $profile) {
   echo 'SQL Statement: ', $profile->getSQLStatement(), '\n';
   echo 'Start Time: ', $profile->getInitialTime(), '\n';
   echo 'Final Time: ', $profile->getFinalTime(), '\n';
   echo 'Total Elapsed Time: ', $profile->getTotalElapsedSeconds(), '\n';
}

Each generated profile contains the duration in milliseconds that each instruction takes to complete as well as the generated SQL statement.