added comments to books

server/models/Comment.js

@@ -0,0 +1,83 @@
+const { Model, DataTypes } = require('sequelize')
+
+class Comment extends Model {
+  static init(sequelize) {
+    return super.init(
+      {
+        id: {
+          type: DataTypes.UUID,
+          defaultValue: DataTypes.UUIDV4,
+          primaryKey: true
+        },
+        text: {
+          type: DataTypes.TEXT,
+          allowNull: false
+        },
+        libraryItemId: {
+          type: DataTypes.UUID,
+          allowNull: false,
+          references: {
+            model: 'libraryItems',
+            key: 'id'
+          },
+          onDelete: 'CASCADE',
+          onUpdate: 'CASCADE'
+        },
+        userId: {
+          type: DataTypes.UUID,
+          allowNull: false,
+          references: {
+            model: 'users',
+            key: 'id'
+          },
+          onDelete: 'CASCADE',
+          onUpdate: 'CASCADE'
+        },
+        createdAt: {
+          type: DataTypes.DATE,
+          allowNull: false,
+          defaultValue: DataTypes.NOW
+        },
+        updatedAt: {
+          type: DataTypes.DATE,
+          allowNull: false,
+          defaultValue: DataTypes.NOW
+        }
+      },
+      {
+        sequelize,
+        modelName: 'comment',
+        tableName: 'comments',
+        timestamps: true
+      }
+    )
+  }
+
+  static associate(models) {
+    Comment.belongsTo(models.user, {
+      foreignKey: 'userId',
+      as: 'user'
+    })
+    Comment.belongsTo(models.libraryItem, {
+      foreignKey: 'libraryItemId',
+      as: 'libraryItem'
+    })
+  }
+
+  toJSON() {
+    return {
+      id: this.id,
+      text: this.text,
+      userId: this.userId,
+      libraryItemId: this.libraryItemId,
+      createdAt: this.createdAt,
+      updatedAt: this.updatedAt,
+      user: this.user ? {
+        id: this.user.id,
+        username: this.user.username
+      } : null
+    }
+  }
+}
+
+module.exports = Comment