dcumcTest/models/Notification.js

const Errors = require('../lib/errors')

module.exports = (sequelize, DataTypes) => {
	let Notification = sequelize.define('Notification', {
		interacted: {
			type: DataTypes.BOOLEAN,
			defaultValue: false
		},
		read: {
			type: DataTypes.BOOLEAN,
			defaultValue: false
		},
		type: DataTypes.ENUM('mention', 'thread update', 'reply') 
	}, {
		classMethods: {
			associate (models) {
				Notification.hasOne(models.PostNotification)
				Notification.belongsTo(models.User)
			},
			filterMentions (mentions) {
				//If mentions is not an array of strings
				if(!Array.isArray(mentions) || mentions.filter(m => typeof m !== 'string').length) {
					throw Errors.sequelizeValidation(sequelize, {
						error: 'mentions must be an array of strings',
						value: mentions
					})
				}

				return mentions.filter((mention, pos, self) => {
					return self.indexOf(mention) === pos
				})
			},
			//Props fields: userFrom, usernameTo, post, type
			async createPostNotification (props) {
				let { PostNotification, User, Post } = sequelize.models

				let userTo = await User.findOne({ where: { username: props.usernameTo } })
				if(!userTo) return null
				
				let notification = await Notification.create({ type: props.type })
				let postNotification = await PostNotification.create()

				await postNotification.setUser(props.userFrom)
				await postNotification.setPost(props.post)

				await notification.setPostNotification(postNotification)
				await notification.setUser(userTo)

				let reloadedNotification = await notification.reload({
					include: [{
						model: PostNotification,
						include: [Post, { model: User, attributes: ['createdAt', 'username', 'color'] }]
					}]
				})

				return reloadedNotification
			}
		},
		instanceMethods: {
			async emitNotificationMessage (ioUsers, io) {
				let User = sequelize.models.User
				let user = await User.findById(this.UserId)
				
				if(ioUsers[user.username]) {
					console.log(ioUsers)
					io.to(ioUsers[user.username])
					  .emit('notification', this.toJSON())
				}
			}
		}
	})

	return Notification
}