Adding more models

server/models/MediaProgress.js

@@ -0,0 +1,75 @@
+const { DataTypes, Model } = require('sequelize')
+
+const uppercaseFirst = str => `${str[0].toUpperCase()}${str.substr(1)}`
+
+/*
+ * Polymorphic association: https://sequelize.org/docs/v6/advanced-association-concepts/polymorphic-associations/
+ * Book has many MediaProgress. PodcastEpisode has many MediaProgress.
+ */
+module.exports = (sequelize) => {
+  class MediaProgress extends Model {
+    getMediaItem(options) {
+      if (!this.mediaItemType) return Promise.resolve(null)
+      const mixinMethodName = `get${uppercaseFirst(this.mediaItemType)}`
+      return this[mixinMethodName](options)
+    }
+  }
+
+  MediaProgress.init({
+    id: {
+      type: DataTypes.UUID,
+      defaultValue: DataTypes.UUIDV4,
+      primaryKey: true
+    },
+    mediaItemId: DataTypes.UUIDV4,
+    mediaItemType: DataTypes.STRING,
+    duration: DataTypes.INTEGER,
+    currentTime: DataTypes.INTEGER,
+    isFinished: DataTypes.BOOLEAN,
+    hideFromContinueListening: DataTypes.BOOLEAN,
+    finishedAt: DataTypes.DATE
+  }, {
+    sequelize,
+    modelName: 'MediaProgress'
+  })
+
+  const { Book, PodcastEpisode, User } = sequelize.models
+  Book.hasMany(MediaProgress, {
+    foreignKey: 'mediaItemId',
+    constraints: false,
+    scope: {
+      mediaItemType: 'book'
+    }
+  })
+  MediaProgress.belongsTo(Book, { foreignKey: 'mediaItemId', constraints: false })
+
+  PodcastEpisode.hasMany(MediaProgress, {
+    foreignKey: 'mediaItemId',
+    constraints: false,
+    scope: {
+      mediaItemType: 'podcastEpisode'
+    }
+  })
+  MediaProgress.belongsTo(PodcastEpisode, { foreignKey: 'mediaItemId', constraints: false })
+
+  MediaProgress.addHook('afterFind', findResult => {
+    if (!Array.isArray(findResult)) findResult = [findResult]
+    for (const instance of findResult) {
+      if (instance.mediaItemType === 'book' && instance.book !== undefined) {
+        instance.mediaItem = instance.book
+      } else if (instance.mediaItemType === 'podcastEpisode' && instance.podcastEpisode !== undefined) {
+        instance.mediaItem = instance.podcastEpisode
+      }
+      // To prevent mistakes:
+      delete instance.book
+      delete instance.dataValues.book
+      delete instance.podcastEpisode
+      delete instance.dataValues.podcastEpisode
+    }
+  })
+
+  User.hasMany(MediaProgress)
+  MediaProgress.belongsTo(User)
+
+  return MediaProgress
+}