resolvers.js

const { AuthenticationError, PubSub } = require('apollo-server');
const Pin = require('./models/Pin');

const pubsub = new PubSub();
const PIN_ADDED = "PIN_ADDED";
const PIN_UPDATED = "PIN_UPDATED";
const PIN_DELETED = "PIN_DELETED";
const CREATE_COMMENT = "CREATE_COMMENT";

const authenticated = (next) => (root, args, ctx, info) => {
  if (!ctx.currentUser) {
    throw new AuthenticationError('You must be logged in');
  }

  return next(root, args, ctx, info);
};

module.exports = {
  Query: {
    me: authenticated((root, args, ctx) => ctx.currentUser),
    getPins: async (root, args, ctx) => {
      const pins = await Pin.find({}).populate('author')
      .populate('comments.author');
      return pins;
    }
  },
  Mutation: {
    createPin: authenticated(async (root, args, ctx) => {
      const newPin = await new Pin({ ...args.input, author: ctx.currentUser._id }).save();
      const pinAdded = await Pin.populate(newPin, 'author');
      pubsub.publish(PIN_ADDED, { pinAdded });
      return pinAdded;
    }),
    deletePin: authenticated(async (root, args, ctx) => {
      const pinDeleted = await Pin.findOneAndDelete(
        { _id: args.pinId }).exec();
      pubsub.publish(PIN_DELETED, { pinDeleted });
      return pinDeleted;
    }),
    createComment: authenticated(async (root, args, ctx) => {
      const newComment = { text: args.text, author: ctx.currentUser._id};
      const pinUpdated = await Pin.findOneAndUpdate(
        {_id: args.pinId}, 
        { $push: { comments: newComment } }, 
        { new: true }
      ).populate('author')
      .populate('comments.author');
      pubsub.publish(PIN_UPDATED, { pinUpdated });
      return pinUpdated;
    }),
  },
  Subscription: {
    pinAdded: {
      subscribe: () => pubsub.asyncIterator(PIN_ADDED)
    },
    pinUpdated: {
      subscribe: () => pubsub.asyncIterator(PIN_UPDATED)
    },
    pinDeleted: {
      subscribe: () => pubsub.asyncIterator(PIN_DELETED)
    }
  }
};