audiobookshelf/server/models/BookAuthor.js

const { DataTypes, Model } = require('sequelize')

class BookAuthor extends Model {
  constructor(values, options) {
    super(values, options)

    /** @type {UUIDV4} */
    this.id
    /** @type {UUIDV4} */
    this.bookId
    /** @type {UUIDV4} */
    this.authorId
    /** @type {Date} */
    this.createdAt
  }

  static removeByIds(authorId = null, bookId = null) {
    const where = {}
    if (authorId) where.authorId = authorId
    if (bookId) where.bookId = bookId
    return this.destroy({
      where
    })
  }

  /**
   * Initialize model
   * @param {import('../Database').sequelize} sequelize 
   */
  static init(sequelize) {
    super.init({
      id: {
        type: DataTypes.UUID,
        defaultValue: DataTypes.UUIDV4,
        primaryKey: true
      }
    }, {
      sequelize,
      modelName: 'bookAuthor',
      timestamps: true,
      updatedAt: false
    })

    // Super Many-to-Many
    // ref: https://sequelize.org/docs/v6/advanced-association-concepts/advanced-many-to-many/#the-best-of-both-worlds-the-super-many-to-many-relationship
    const { book, author } = sequelize.models
    book.belongsToMany(author, { through: BookAuthor })
    author.belongsToMany(book, { through: BookAuthor })

    book.hasMany(BookAuthor, {
      onDelete: 'CASCADE'
    })
    BookAuthor.belongsTo(book)

    author.hasMany(BookAuthor, {
      onDelete: 'CASCADE'
    })
    BookAuthor.belongsTo(author)
  }
}
module.exports = BookAuthor