Replacing Associative Arrays with Objects

Legacy code passes associative arrays everywhere ($user['email']), so typos and missing keys only fail at runtime. Introduce small DTOs/value objects with typed properties (7.4) or getters, created once from the array at the boundary. Document remaining array shapes with PHPStan's array{id:int, email:string} until they're converted.

<?php
final class CustomerDto
{
    public int $id;
    public string $email;
    public ?string $company;

    public static function fromRow(array $row): self
    {
        $dto = new self();
        $dto->id = (int) $row['id'];
        $dto->email = (string) $row['email'];
        $dto->company = $row['company'] !== '' ? $row['company'] : null;
        return $dto;
    }
}
// PHP 8 version later: constructor promotion + readonly.

Common pitfalls

• Converting everything at once instead of at the boundaries you touch.
• DTOs with public mutable properties used as domain objects with rules.
• Keeping both arrays and objects in parallel indefinitely.

Key points

• Typed objects catch errors earlier
• Convert at the boundary
• Document remaining arrays with shapes

Further reading: PHPStan: array shapes