audiobookshelf/server/models/PlaylistMediaItem.js

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

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

    /** @type {UUIDV4} */
    this.id
    /** @type {UUIDV4} */
    this.mediaItemId
    /** @type {string} */
    this.mediaItemType
    /** @type {number} */
    this.order
    /** @type {UUIDV4} */
    this.playlistId
    /** @type {Date} */
    this.createdAt
  }

  static removeByIds(playlistId, mediaItemId) {
    return this.destroy({
      where: {
        playlistId,
        mediaItemId
      }
    })
  }

  getMediaItem(options) {
    if (!this.mediaItemType) return Promise.resolve(null)
    const mixinMethodName = `get${this.sequelize.uppercaseFirst(this.mediaItemType)}`
    return this[mixinMethodName](options)
  }

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

    const { book, podcastEpisode, playlist } = sequelize.models

    book.hasMany(PlaylistMediaItem, {
      foreignKey: 'mediaItemId',
      constraints: false,
      scope: {
        mediaItemType: 'book'
      }
    })
    PlaylistMediaItem.belongsTo(book, { foreignKey: 'mediaItemId', constraints: false })

    podcastEpisode.hasOne(PlaylistMediaItem, {
      foreignKey: 'mediaItemId',
      constraints: false,
      scope: {
        mediaItemType: 'podcastEpisode'
      }
    })
    PlaylistMediaItem.belongsTo(podcastEpisode, { foreignKey: 'mediaItemId', constraints: false })

    PlaylistMediaItem.addHook('afterFind', findResult => {
      if (!findResult) return

      if (!Array.isArray(findResult)) findResult = [findResult]

      for (const instance of findResult) {
        if (instance.mediaItemType === 'book' && instance.book !== undefined) {
          instance.mediaItem = instance.book
          instance.dataValues.mediaItem = instance.dataValues.book
        } else if (instance.mediaItemType === 'podcastEpisode' && instance.podcastEpisode !== undefined) {
          instance.mediaItem = instance.podcastEpisode
          instance.dataValues.mediaItem = instance.dataValues.podcastEpisode
        }
        // To prevent mistakes:
        delete instance.book
        delete instance.dataValues.book
        delete instance.podcastEpisode
        delete instance.dataValues.podcastEpisode
      }
    })

    playlist.hasMany(PlaylistMediaItem, {
      onDelete: 'CASCADE'
    })
    PlaylistMediaItem.belongsTo(playlist)
  }
}

module.exports = PlaylistMediaItem