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