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

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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}/

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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}/

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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

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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;
}

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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

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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