? PHP OOP __isset() Magic Method

? Quick Overview

The __isset() magic method in PHP is automatically triggered when isset() or empty() is used on inaccessible or non-existent object properties. It allows developers to define custom behavior for property existence checks.

? Key Concepts

• Triggered by isset() and empty().
• Works with inaccessible or undefined properties.
• Receives the property name as a parameter.
• Returns a boolean value.
• Often paired with __get() and __set().

? Syntax & Theory

The __isset() method enables controlled property checking, useful for dynamic properties, lazy loading, and encapsulation of private or protected data.

? Code Example

// Demonstrates usage of __isset() with dynamic properties
data[$name] = $value;
}

public function __get($name) {
return $this->data[$name] ?? null;
}

public function __isset($name) {
return isset($this->data[$name]);
}
}

$user = new User();
$user->name = "Meghraj";

if (isset($user->name)) {
echo "Property 'name' is set";
}

if (empty($user->email)) {
echo "Property 'email' is not set";
}
?>

? Live Output / Explanation

The first condition confirms that name exists and is set. The second condition detects that email does not exist, triggering __isset() and returning false.

? Interactive Concept

You can experiment by adding more dynamic properties and testing them with isset() and empty() to observe how __isset() controls the behavior.

?️ Use Cases

• Dynamic property handling
• Lazy-loading object properties
• Encapsulation of internal data arrays
• Preventing undefined property errors