subdocument.js

const mongoose = require('mongoose');

const UserSchema = new mongoose.Schema({
  username: {
    type: String,
    required: true
  },
  fullName: {
    type: String,
    required: true
  },
  addresses: [{
    street: String,
    city: String,
    likes: { type: Number, default: 0 },
    state: {
      type: String,
      enum: ['AL', 'AK', 'AZ', 'AR', 'CA', 'CO', 'CT']
    },
    zip: Number
  }]
});

const User = mongoose.model('User', UserSchema);

mongoose.connect('mongodb://localhost:27017/demo-books', { useMongoClient: true })
  .then(() => {
    return mongoose.connection.db.dropDatabase();
  })

  // ***************************** 
  // Create a new User
  // *****************************   
  .then(() => {

    return User.create([
      {
        _id: 'aaaaaaaaaaaaaaaaaaaaaaaa', username: 'aalabaster', fullName: 'Alice Alabaster',
        addresses: [
          { street: '123 Main St.', city: 'Springfield', state: 'CO', zip: 12345 }]
      },
      { _id: 'bbbbbbbbbbbbbbbbbbbbbbbb', username: 'bbaker', fullName: 'Bob Baker', addresses: [{ street: '123 Front St.', city: 'Downtown', state: 'CA', zip: 12345 }] },
      { _id: 'cccccccccccccccccccccccc', username: 'cconway', fullName: 'Chuck Conway' }
    ]);

  }).then(results => {
    console.log('create new item: \n', results);
  })


  // ***************************** 
  // $push a new item onto an array
  // using .findByIdAndUpdate()
  // ***************************** 
  .then(() => {
    return User
      .findByIdAndUpdate(
        'aaaaaaaaaaaaaaaaaaaaaaaa',
        {
          '$push': {
            addresses: { street: '789 Cactus St.', city: 'Scottsdale', state: 'AZ', zip: 56789 }
          }
        },
        { new: true }
      );

  }).then(results => {
    console.log('$push results: \n', results);
  })



  // ***************************** 
  // Update a single item in the array using the $ placeholder
  // using findOneAndUpdate()
  // ***************************** 
  .then(() => {
    return User
      .findOneAndUpdate(
        { username: 'aalabaster', 'addresses.state': 'AZ' },
        { 'addresses.$.city': 'Phoenix' },
        { new: true }
      );
  }).then(results => {
    console.log('update', results);
  })

  // ***************************** 
  // $inc a property in an array
  // findOneAndUpdate()
  // *****************************   
  .then(() => {
    return User
      .findOneAndUpdate(
        { username: 'aalabaster', 'addresses.state': 'AZ' },
        { $inc: { 'addresses.$.likes': 1 } },
        { new: true }
      );
  }).then(results => {
    console.log('update', results);
  })

  // ***************************** 
  // $pull (remove) an item from an Array
  // findOneAndUpdate()
  // *****************************   
  .then(() => {
    return User
      .findByIdAndUpdate(
        'aaaaaaaaaaaaaaaaaaaaaaaa',
        { $pull: { addresses: { city: 'Springfield' } } },
        { new: true }
      );
  }).then(results => {
    console.log('remove', results);
  })

  .then(() => {

    return mongoose.disconnect();
  }).catch((err) => {
    console.error(err);
    return mongoose.disconnect();
  });