Try It Yourself - SyntaxStudy Editor

HTML / CSS / JS

const mongoose = require('mongoose')

// Schema with a reference
const postSchema = new mongoose.Schema({
  title:    { type: String, required: true },
  body:     String,
  author:   { type: mongoose.Schema.Types.ObjectId, ref: 'User' },
  tags:     [String],
  published: { type: Boolean, default: false }
}, { timestamps: true })

const Post = mongoose.model('Post', postSchema)

// --- Querying ---

// Find with populate — resolves authorId to full User document
const posts = await Post.find({ published: true })
  .populate('author', 'name email -_id')  // only name and email
  .sort({ createdAt: -1 })
  .limit(10)
  .lean()   // returns plain objects (faster)

// findById
const post = await Post.findById('64a1f2b3c4d5e6f7a8b9c0d1').populate('author')

// findOne with conditions
const latest = await Post.findOne({ tags: 'mongodb' }).sort({ createdAt: -1 })

// Update and return new document
const updated = await Post.findByIdAndUpdate(
  id,
  { $set: { published: true } },
  { new: true, runValidators: true }
)

// Delete
await Post.findByIdAndDelete(id)