Persistence (trait)

Overview:

Persistence provides a persistence layer for Model via SQL.

Use the Persistence trait to give models SQL-backed load/save behavior with configurable table and primary-key conventions.

Key behavior:

• Default table name is the pluralized class name.
• Default primary key is id unless _PRIMARY_KEY_ is defined.

Public API:

• ::persistOn($table, array $options = []) sets table and options.
• ::onSave(callable $callback) overrides save logic.
• ::onLoad(callable $callback) overrides load logic.
• ::load($pk) loads instance by primary key.
• ->save() persists instance (insert or update).

Example:

class User extends Model { public $id, $name; }
User::persistOn('users', ['key' => 'id']);

The Persistence module allow you to augment a class with a database persistence layer.

Standard persistence

---

class User {
  // Add persistence feat
  use Persistence;

  public $id, $email, $name;

}

// Enable persistence defining the target database table
User::persistOn('users',[
  'key' => 'id'  // The primary key, 'id' is the default.
]);

$me = new User();
$me->id = 1000;
$me->email = 'john@email.com';
$me->name = 'John Appleseed';

// Save data on database
$me->save();

// Retrieve an user by it's primary key
$current_user = User::load(1000);
echo $current_user->email;

john@email.com

Override Save/Load callbacks

---

You can override the save/load callback with custom methods.

// Persist on files instead of Database

User::onLoad(function($id, $table, $options){
  $keyname = $options['key'];
  $path = '/data/' . $table . '/' . Hash::md5($id) . '.php';
  $obj = null;
  if (file_exists($path)) $obj = unserialize(file_get_contents($path));
  return $obj;
});

User::onSave(function($table, $options){
  // The current object is binded on $this variable
  $keyname = $options['key'];
  $path = '/data/' . $table . '/' . Hash::md5( $this->$keyname ) . '.php';
  return file_put_contents(serialize($this)) > 0;
});