rest-controller-conventions

REST Controller Conventions (Symfony, no API Platform)

Controller shape

• One final class per resource, #[Route] prefix on the class.
• Constructor injection of services only (no repositories — see layered-architecture).
• Map the request body with #[MapRequestPayload] and query params with #[MapQueryString] into DTOs.
• Return JsonResponse via $this->json(...) with explicit status codes.

#[Route('/api/orders')]
final class OrderController extends AbstractController
{
    public function __construct(private readonly OrderService $orders) {}

    #[Route('', methods: ['GET'])]
    public function list(#[MapQueryString] OrderListQuery $query): JsonResponse
    {
        $page = $this->orders->list($query);

        return $this->json($page, context: ['groups' => ['order:read']]);
    }

    #[Route('/{id}', methods: ['GET'])]
    public function show(Uuid $id): JsonResponse
    {
        return $this->json(
            $this->orders->get($id),
            context: ['groups' => ['order:read', 'order:detail']],
        );
    }

    #[Route('', methods: ['POST'])]
    public function create(#[MapRequestPayload] CreateOrderRequest $request): JsonResponse
    {
        $order = $this->orders->createOrder($request);

        return $this->json(
            OrderResponse::fromEntity($order),
            Response::HTTP_CREATED,
            ['Location' => $this->generateUrl('order_show', ['id' => $order->getId()])],
            ['groups' => ['order:read']],
        );
    }

    #[Route('/{id}', methods: ['DELETE'])]
    public function delete(Uuid $id): JsonResponse
    {
        $this->orders->cancel($id);

        return new JsonResponse(null, Response::HTTP_NO_CONTENT);
    }
}

HTTP status codes

Situation	Status
Successful GET	200 OK
Resource created	201 Created + Location header
Accepted, processed async	202 Accepted
Successful DELETE / no body	204 No Content
Validation failed	422 Unprocessable Entity
Malformed JSON	400 Bad Request
Unauthenticated	401 Unauthorized
Authenticated but forbidden	403 Forbidden
Not found	404 Not Found
Conflict (duplicate, version)	409 Conflict

Don't return 200 for everything. Map domain exceptions to status codes in an exception listener (see problem-details-rfc9457).

Serialization groups, not entity exposure

Never serialize a Doctrine entity straight to the client without scoping. Either map to a response DTO or apply #[Groups] and pass the group in the serialization context.

// On the entity / DTO
#[Groups(['order:read'])]
private string $customerEmail;

#[Groups(['order:detail'])]   // only on the detail endpoint
private array $internalNotes;

Request mapping & validation

#[MapRequestPayload] deserializes and validates the DTO (via the Validator). On constraint failure it throws automatically → your exception listener turns it into a 422.

public function create(#[MapRequestPayload] CreateOrderRequest $request): JsonResponse

Validate query params the same way with #[MapQueryString]. See dto-and-validation.

Pagination

Return a stable envelope, never a bare array, so you can add metadata without a breaking change:

{
  "data": [ ... ],
  "page": 1,
  "perPage": 20,
  "total": 137
}

return $this->json(new PaginatedResponse($items, $page, $perPage, $total), context: ['groups' => ['order:read']]);

Cap perPage server-side. For deep pages, prefer keyset pagination (see doctrine-query-optimization).

Routing conventions

• Plural nouns: /orders, /orders/{id}, /orders/{id}/lines.
• No verbs in paths (/orders POST, not /createOrder).
• Use HTTP methods for actions; reserve sub-resources for relationships.
• Constrain params: #[Route('/{id}', requirements: ['id' => Requirement::UUID])].

Gotchas

• Agent returns $this->json($entity) without groups — scope with #[Groups] or map to a DTO; otherwise lazy associations serialize and leak fields.
• Agent returns 200 for created/deleted resources — use 201 (+ Location) and 204.
• Agent decodes JSON by hand (json_decode($request->getContent())) — use #[MapRequestPayload] + DTO.
• Agent puts verbs in routes (/getOrders, /createOrder) — use nouns + HTTP methods.
• Agent returns a bare JSON array for collections — use a paginated envelope.
• Agent catches NotFoundException in the controller — let the exception listener map it to 404.
• Agent skips param requirements — constrain {id} to UUID to avoid route collisions.