How do you handle exceptions differently in a filter depending on whether the request is HTTP, WebSocket, or RPC?

Q: How do you handle exceptions differently in a filter depending on whether the request is HTTP, WebSocket, or RPC?

@Catch() export class UniversalExceptionFilter implements ExceptionFilter { catch(exception: unknown, host: ArgumentsHost): void { const type = host.getType (); if (type === 'http') { const ctx = host.switchToHttp(); const res = ctx.getResponse (); const status = exception instanceof HttpException ? exception.getStatus() : 500; res.status(status).json({ message: this.getMessage(exception) }); } else if (type === 'ws') { const client = host.switchToWs().getClient(); client.emit('exception', { status: 'error', message: this.getMessage(exception), }); } else if (type === 'rpc') { return throwError(() => this.getMessage(exception)) as any; } } private getMessage(ex: unknown): string { if (ex instanceof HttpException) return ex.message; if (ex instanceof Error) return 'Internal error'; return 'Unknown error'; } } HTTP — use host.switchToHttp().getResponse().status().json() for standard REST error responses. WebSocket — use host.switchToWs().getClient().emit('exception', ...) to send the error to the socket. RPC — return a throwError() observable; the microservice framework handles serialization. WsException from @nestjs/websockets should be thrown in WebSocket context for proper formatting. A single filter registered globally can handle all transports by branching on host.getType().

Difficulty: 5/10

Exception Filters, Transport Detection, NestJS

Use host.getType() to detect the transport and branch accordingly. Each transport has its own error format: HTTP uses res.status().json(), WebSocket emits an error event to the socket client, and RPC returns a throwError observable. Throw the transport-appropriate exception in each branch.

Universal exception filter across transports

Transport-specific error handling:

1
HTTP — use host.switchToHttp().getResponse().status().json() for standard REST error responses.
2

How do you handle exceptions differently in a filter depending on whether the request is HTTP, WebSocket, or RPC?

Difficulty: 5/10

Exception Filters, Transport Detection, NestJS

Use host.getType() to detect the transport and branch accordingly. Each transport has its own error format: HTTP uses res.status().json(), WebSocket emits an error event to the socket client, and RPC returns a throwError observable. Throw the transport-appropriate exception in each branch.

Universal exception filter across transports

Transport-specific error handling:

1
HTTP — use host.switchToHttp().getResponse().status().json() for standard REST error responses.
2

How do you handle exceptions differently in a filter depending on whether the request is HTTP, WebSocket, or RPC?

Use host.getType() to detect the transport and branch accordingly. Each transport has its own error format: HTTP uses res.status().json(), WebSocket emits an error event to the socket client, and RPC returns a throwError observable. Throw the transport-appropriate exception in each branch.

How do you handle exceptions differently in a filter depending on whether the request is HTTP, WebSocket, or RPC?

Use host.getType() to detect the transport and branch accordingly. Each transport has its own error format: HTTP uses res.status().json(), WebSocket emits an error event to the socket client, and RPC returns a throwError observable. Throw the transport-appropriate exception in each branch.

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