Add favorite property for items and associated filters.

server/models/UserFavorite.js

@@ -0,0 +1,66 @@
+const { DataTypes, Model } = require('sequelize')
+
+class UserFavorite extends Model {
+  constructor(values, options) {
+    super(values, options)
+
+    /** @type {UUIDV4} */
+    this.id
+    /** @type {UUIDV4} */
+    this.libraryItemId
+    /** @type {UUIDV4} */
+    this.userId
+  }
+
+  static init(sequelize) {
+    super.init(
+      {
+        id: {
+          type: DataTypes.UUID,
+          defaultValue: DataTypes.UUIDV4,
+          primaryKey: true
+        },
+        libraryItemId: DataTypes.UUID,
+        userId: DataTypes.UUID
+      },
+      {
+        sequelize,
+        modelName: 'userFavorite',
+        indexes: [
+          {
+            fields: ['userId']
+          },
+          {
+            fields: ['libraryItemId']
+          },
+          {
+            unique: true,
+            fields: ['libraryItemId', 'userId'],
+          }
+        ]
+      }
+    )
+
+    const { libraryItem, user } = sequelize.models
+
+    libraryItem.hasMany(UserFavorite, {
+      foreignKey: 'libraryItemId',
+      onDelete: 'CASCADE'
+    })
+    UserFavorite.belongsTo(libraryItem, { foreignKey: 'libraryItemId' })
+
+    user.hasMany(UserFavorite, {
+      foreignKey: 'userId',
+      onDelete: 'CASCADE'
+    })
+    user.belongsToMany(libraryItem, {
+      through: UserFavorite,
+      foreignKey: 'userId',
+      otherKey: 'libraryItemId',
+      as: 'favorites'
+    })
+    UserFavorite.belongsTo(user, { foreignKey: 'userId' })
+  }
+}
+
+module.exports = UserFavorite