What happens to REQUEST-scoped providers during WebSocket connections or microservice message handling in NestJS?

Q: What happens to REQUEST-scoped providers during WebSocket connections or microservice message handling in NestJS?

// HTTP context — REQUEST resolves to Express/Fastify Request object @Injectable({ scope: Scope.REQUEST }) export class HttpAuditService { constructor(@Inject(REQUEST) private req: Request) {} getIp() { return this.req.ip; } } // Microservice context — REQUEST resolves to the message payload @Injectable({ scope: Scope.REQUEST }) export class MessageAuditService { constructor(@Inject(REQUEST) private msg: Record ) {} getCorrelationId() { return this.msg.correlationId; } } // WebSocket context — REQUEST resolves to the Socket instance @Injectable({ scope: Scope.REQUEST }) export class WsSessionService { constructor(@Inject(REQUEST) private socket: Socket) {} getRoomId() { return this.socket.data.roomId; } } HTTP (Express/Fastify) — resolves to the native Request object with headers, body, ip, user, etc. WebSockets — resolves to the Socket.IO Socket client instance. Microservices (TCP, Redis, Kafka) — resolves to the incoming message/event payload object. GraphQL — use the CONTEXT token from @nestjs/graphql instead of REQUEST for the GraphQL execution context. If a REQUEST-scoped service is shared across transports, add runtime type checks on the injected object.

Difficulty: 6/10

request scope, WebSocket gateway, microservice messages

REQUEST scope is not limited to HTTP. For WebSockets the REQUEST token resolves to the Socket client object. For microservices it resolves to the incoming message payload. The shape of the injected object differs per transport so code using @Inject(REQUEST) must be written defensively if shared across multiple transports.

REQUEST token in microservice context

Transport-specific REQUEST token shapes:

1
HTTP (Express/Fastify) — resolves to the native Request object with headers, body, ip, user, etc.
2
WebSockets — resolves to the Socket.IO Socket client instance.
3
Microservices (TCP, Redis, Kafka) — resolves to the incoming message/event payload object.
4
GraphQL — use the CONTEXT token from @nestjs/graphql instead of REQUEST for the GraphQL execution context.
5
If a REQUEST-scoped service is shared across transports, add runtime type checks on the injected object.

Scenario Questions

0-2 years experience

2-5 years experience

1During a recent sprint, a microservice started throwing memory‑leak errors after handling many messages. The team suspects a request‑scoped provider. Walk me through how you would investigate and fix it.

What happens to REQUEST-scoped providers during WebSocket connections or microservice message handling in NestJS?

Scenario Questions

Follow-up Questions