poll.resolvers.js

// ... imports

export default {
  // ... queries

  mutations: {
    // ... createPoll

    async voteOnPoll(parent, args) {
      const poll = await pollService.voteOnPoll(args.optionId).catch();

      pubsub.publish(OPTION_VOTED, {
        [OPTION_VOTED]: poll.options.find((option) => {
          return option._id.toString() === args.optionId
        })
      })

      return poll
    }
  },

  subscriptions: {
    // ... poll create subscription

    [OPTION_VOTED]: {
      subscribe: () => pubsub.asyncIterator(OPTION_VOTED),
    }
  },
}