Request & Reply Objects

request and reply

request contains the incoming HTTP request details (URL, headers, body, params, query). reply is an object with methods to send the response—it's pooled for performance.

Reading request data

Access path params, query strings, headers, and body from the request object.

fastify.get('/users/:id', async (request, reply) => {
  const { id } = request.params;
  const { filter } = request.query;
  const token = request.headers.authorization;
  
  return { userId: id, filter, hasToken: !!token };
});

Sending replies

Return an object (auto-serialized to JSON) or use reply methods for custom status codes and headers.

fastify.post('/items', async (request, reply) => {
  // Auto-JSON serialization
  return { id: 1, status: 'created' };
});

fastify.delete('/items/:id', async (request, reply) => {
  // Custom status and location header
  return reply.status(204).send();
});