Developing with MongoDB

Quick Start

// Schema with Mongoose
import mongoose, { Schema, Document } from 'mongoose';

interface IUser extends Document {
  email: string;
  profile: { firstName: string; lastName: string };
  createdAt: Date;
}

const userSchema = new Schema<IUser>({
  email: { type: String, required: true, unique: true, lowercase: true },
  profile: {
    firstName: { type: String, required: true },
    lastName: { type: String, required: true },
  },
}, { timestamps: true });

userSchema.index({ email: 1 });
export const User = mongoose.model<IUser>('User', userSchema);

Features

Feature	Description	Guide
Document Schema	Type-safe schema design with Mongoose	Embed related data, use references for large collections
CRUD Operations	Create, read, update, delete with type safety	Use `findById`, `findOne`, `updateOne`, `deleteOne`
Aggregation Pipelines	Complex data transformations and analytics	Chain `$match`, `$group`, `$lookup`, `$project` stages
Indexing	Query optimization with proper indexes	Create compound indexes matching query patterns
Transactions	Multi-document ACID operations	Use sessions for operations requiring atomicity
Change Streams	Real-time data change notifications	Watch collections for inserts, updates, deletes

Common Patterns

Repository Pattern with Pagination

async findPaginated(filter: FilterQuery<IUser>, page = 1, limit = 20) {
  const [data, total] = await Promise.all([
    User.find(filter).sort({ createdAt: -1 }).skip((page - 1) * limit).limit(limit),
    User.countDocuments(filter),
  ]);
  return { data, pagination: { page, limit, total, totalPages: Math.ceil(total / limit) } };
}

Aggregation Pipeline

const stats = await Order.aggregate([
  { $match: { status: 'completed', createdAt: { $gte: startDate } } },
  { $group: { _id: '$userId', total: { $sum: '$amount' }, count: { $sum: 1 } } },
  { $sort: { total: -1 } },
  { $limit: 10 },
]);

Transaction for Order Creation

const session = await mongoose.startSession();
try {
  session.startTransaction();
  await Product.updateOne({ _id: productId }, { $inc: { stock: -quantity } }, { session });
  const order = await Order.create([{ userId, items, total }], { session });
  await session.commitTransaction();
  return order[0];
} catch (error) {
  await session.abortTransaction();
  throw error;
} finally {
  session.endSession();
}

Best Practices

Do	Avoid
Design schemas based on query patterns	Embedding large arrays in documents
Create indexes for frequently queried fields	Using `$where` or mapReduce in production
Use `lean()` for read-only queries	Skipping validation on writes
Implement pagination for large datasets	Storing large files directly (use GridFS)
Set connection pool size appropriately	Hardcoding connection strings
Use transactions for multi-document ops	Ignoring index usage in explain plans
Add TTL indexes for expiring data	Creating too many indexes (write overhead)