Connecting to a Database

npm install mongoose

// db.js
const mongoose = require("mongoose");

async function connectDB() {
  await mongoose.connect(process.env.MONGODB_URI);
  console.log("Connected to MongoDB");
}

module.exports = connectDB;

// models/Course.js
const mongoose = require("mongoose");

const courseSchema = new mongoose.Schema({
  title:       { type: String, required: true, trim: true },
  slug:        { type: String, required: true, unique: true },
  description: { type: String },
  level:       { type: String, enum: ["beginner", "intermediate", "advanced"] },
  chapters:    { type: Number, default: 0 },
  isLive:      { type: Boolean, default: false },
  createdAt:   { type: Date, default: Date.now },
});

module.exports = mongoose.model("Course", courseSchema);

const Course = require("./models/Course");

// Create
const course = await Course.create({
  title: "JavaScript Basics",
  slug: "javascript-basics",
  level: "beginner",
});

// Read
const all      = await Course.find({ isLive: true });
const one      = await Course.findById(id);
const bySlug   = await Course.findOne({ slug: "nextjs" });

// Read with filters, sort, limit
const courses = await Course
  .find({ level: "beginner" })
  .sort({ createdAt: -1 })
  .limit(10)
  .select("title slug level");  // only return these fields

// Update
await Course.findByIdAndUpdate(id, { chapters: 14 }, { new: true });

// Delete
await Course.findByIdAndDelete(id);