const mongoose = require('mongoose'); const CommentSchema = new mongoose.Schema( { body: String, author: { type: mongoose.Schema.Types.ObjectId, ref: 'User' }, track: { type: mongoose.Schema.Types.ObjectId, ref: 'Track' }, }, { timestamps: true }, ); // Requires population of author CommentSchema.methods.toJSONFor = function (user) { return { id: this._id, body: this.body, createdAt: this.createdAt, author: this.author.toProfileJSONFor(user), }; }; mongoose.model('Comment', CommentSchema);