MongoDB Repository Library

A lightweight, type-safe wrapper for the MongoDB Node.js driver using the Repository pattern.

Overview

This library consists of two main components:

1. MongoBackend: Manages the database connection and serves as a factory for repositories.
2. BaseRepository: An abstract class providing standard CRUD operations, automatic timestamping, and versioning.

1. MongoBackend

Configuration & Connection

import { MongoClient } from 'mongodb';
import { MongoBackend } from '@knymbus/mongobackend';

const client = new MongoClient('mongodb://localhost:27017');

const backend = new MongoBackend({
    mongo: client,
    app: 'my_application_db'
});

// Explicitly connect and ping the server
await backend.connect();

// Check status
const isActive = await backend.isConnected(); 

Repository Factory

// Automatically injects the DB instance into your repository class
const userRepo = backend.getRepo(UserRepository);

2. BaseRepository

To create a repository, extend the BaseRepository class and provide your document type.

Implementation

import { BaseRepository } from '@knymbus/mongobackend';
import { Db, ClientSession, ObjectId } from 'mongodb';

interface User {
    _id?: ObjectId;
    name: string;
    email: string;
    createdAt?: Date;
    updatedAt?: Date;
    version?: number;
}

export class UserRepository extends BaseRepository<User> {
    constructor(db: Db, session?: ClientSession) {
        // Pass the database and the collection name
        super(db, 'users', session);
    }
}

Core Methods

Create

Automatically adds createdAt, updatedAt, and version: 1.

const user = await userRepo.create({ name: 'Alice', email: '[email protected]' });

Read

// Find by ID (String or ObjectId)
const user = await userRepo.findById('65f1...89a');

// Find One by filter
const user = await userRepo.findOne({ email: '[email protected]' });

// Find All
const activeUsers = await userRepo.findAll({ status: 'active' });

// Count
const total = await userRepo.count({ role: 'admin' });

Update

// Update by ID
const updated = await userRepo.updateById(userId, { $set: { name: 'Alice Smith' } });

// Find and Update with filter
const result = await userRepo.update({ email: '[email protected]' }, { $set: { email: '[email protected]' } });

Delete

await userRepo.deleteById(userId);
await userRepo.deleteAll({ status: 'inactive' });

Advanced Operations

Bulk Write

await userRepo.bulkWrite([
    { insertOne: { document: { name: 'Bob' } } },
    { updateOne: { filter: { name: 'Alice' }, update: { $set: { status: 'active' } } } }
]);

Aggregation

const cursor = userRepo.aggregate([
    { $match: { score: { (gt: 80 } } },     {\)sort: { score: -1 } }
]);
const topStudents = await cursor.toArray();

Dynamic Collection Switching

Create a new instance of the same repository class targeting a different collection:

const logRepo = userRepo.forCollection('users_archive');

Testing with Jest

To run the included test suite, ensure you have jest, ts-jest, and @types/jest installed.

# Run tests
npm test

The tests use a mocked mongodb driver to ensure logic (like timestamp injection and ID conversion) works correctly without requiring a live database.