DTO Generator

Generate DTOs for transferring data between layers, API boundaries, and external systems.

DTO Characteristics

• Immutable: Read-only after creation
• No Behavior: Pure data container, no business logic
• Serializable: JSON/array conversion support
• Typed: Strictly typed properties
• Validated: Input validation at creation (for requests)
• Layer-Specific: Different DTOs for different purposes

DTO Types

| Type | Purpose | Location | |------|---------|----------| | Request DTO | API input validation | Presentation layer | | Response DTO | API output formatting | Presentation layer | | Command DTO | Use case input | Application layer | | Query Result DTO | Read model output | Application layer | | Integration DTO | External API data | Infrastructure layer |

---

Generation Process

Step 1: Identify DTO Type

Determine the purpose and layer for the DTO.

Step 2: Generate DTO Class

Path based on type:

• Request: src/Presentation/Api/{Context}/Request/
• Response: src/Presentation/Api/{Context}/Response/
• Application: src/Application/{Context}/DTO/
• Integration: src/Infrastructure/ExternalApi/{Service}/DTO/

Step 3: Add Conversion Methods

1. fromArray() — Create from raw data
2. fromEntity() — Create from domain entity (Response DTOs)
3. toArray() / jsonSerialize() — Serialize for output

Step 4: Generate Tests

Path: tests/Unit/{Layer}/{Context}/{Type}/

---

File Placement

| Type | Path | |------|------| | Request DTO | src/Presentation/Api/{Context}/Request/ | | Response DTO | src/Presentation/Api/{Context}/Response/ | | Application DTO | src/Application/{Context}/DTO/ | | Integration DTO | src/Infrastructure/ExternalApi/{Service}/DTO/ | | Unit Tests | tests/Unit/{Layer}/{Context}/{Type}/ |

---

Naming Conventions

| Type | Pattern | Example | |------|---------|---------| | Request | {Action}{Entity}Request | CreateOrderRequest, UpdateUserRequest | | Response | {Entity}Response | OrderResponse, UserResponse | | Collection | {Entity}CollectionResponse | OrderCollectionResponse | | Application | {Entity}DTO | UserDTO, OrderDTO | | Integration | {Service}{Action}Response | PaymentGatewayResponse |

---

Quick Template Reference

Request DTO

final readonly class {Name}Request
{
    public function __construct(
        #[Assert\NotBlank]
        public string $field,
        #[Assert\Valid]
        public ?NestedRequest $nested = null
    ) {}

    public static function fromArray(array $data): self;
}

Response DTO

final readonly class {Name}Response implements \JsonSerializable
{
    public function __construct(
        public string $id,
        public string $name,
        /** @var array<ItemResponse> */
        public array $items = []
    ) {}

    public static function fromEntity({Entity} $entity): self;
    public function jsonSerialize(): array;
}

Application DTO

final readonly class {Name}DTO
{
    public function __construct(
        public string $id,
        public string $field
    ) {}

    public static function fromRequest({Name}Request $request): self;
    public function toArray(): array;
}

---

Anti-patterns to Avoid

| Anti-pattern | Problem | Solution | |--------------|---------|----------| | Business Logic | DTO with calculations | Keep DTOs data-only | | Mutable DTO | setters, state changes | Use readonly, immutable | | Domain Objects | Returning entities from API | Map to Response DTO | | Anemic Validation | No input validation | Use Assert attributes | | Deep Nesting | Complex nested DTOs | Flatten or split | | Missing Serialization | No JSON support | Implement JsonSerializable |

---

References

For complete PHP templates and examples, see:

• references/templates.md — Request, Response, Application, Collection, Integration DTO templates
• references/examples.md — Order, User, Payment examples and tests