What is the purpose of the Data Transfer Object (DTO) pattern in software architecture?

The DTO (Data Transfer Object) pattern is used for transferring data between layers of an application or between different systems. Its main goal is to encapsulate data in a simple object without business logic to facilitate transfer and serialization.

Applying DTO helps to:

• Isolate internal data models from external interfaces.
• Reduce the amount of data transferred by including only necessary fields.
• Simplify serialization and deserialization of data (e.g., in JSON).
• Improve code readability and maintainability by separating data from logic.

In PHP, DTOs are often implemented as simple classes with public properties or getters/setters, without methods other than the constructor.

Example of a DTO in PHP:

class UserDTO {
    public string $name;
    public int $age;

    public function __construct(string $name, int $age) {
        $this->name = $name;
        $this->age = $age;
    }
}

Such an object can be passed between layers, for example, from a controller to a service, without revealing internal model details.