Entity manager

Instantiation

The entity manager is represented by the Opis\ORM\EntityManager class, and its main function is to provide methods for creating, fetching, updating, and deleting entities.

The constructor of the entity manager takes as an argument an instance of the Opis\Database\Connection class, that will be further used to establish a connection to the database.

use Opis\ORM\EntityManager;
use Opis\Database\Connection;

$connection = new Connection("mysql:dbname=test", "root", "secret");
$orm = new EntityManager($connection);

Creating entities

Entities are created with the help of the create method. This method takes as an argument the class name of the entity.

use My\Blog\User;

/**
 * Create a new entity
 * @var $user \My\Blog\User
 */
$user = $orm->create(User::class);

Persisting entities

The newly created entity is not persisted into the database until the save method is called. This method takes as an argument an instance of an entity and returns true if the entity was successfully persisted, or false otherwise.

if ($orm->save($user)) {
    echo "Entity was saved";
} else {
    die("Something went wrong");
}

The same method can be used to persist an existing entity after it was modified.

use My\Blog\User;

$user = $orm->create(User::class);
$user->setName('Foo');

if (!$orm->save($user)) {
    die("Something went wrong");
}

// Modify entity
$user->setName('Bar');
// Update entity
$orm->save($user);

Fetching entities

Fetching existing records is done with the help of the query method. The method returns an instance of a query builder that provides various methods that can be used to filter records.

// Get a User entiy by ID
$user = $orm->query(User::class)->find(1);

You can achieve the same thing as above by directly invoking the entity manager.

// Get a User entiy by ID
$user = $orm(User::class)->find(1);

Deleting entities

Deleting an existing entity is done with the help of the delete method. The method takes as an argument an entity instance and returns true if the entity is successfully deleted, or false otherwise.

if (!$orm->delete($user)) {
    die('Could not delete user');
}