mongodb-frameworks

MongoDB Framework Patterns

Mongoose (Node.js)

Schema Best Practices

• Always define collection option explicitly
• Use timestamps: true for automatic createdAt/updatedAt
• Define indexes on schema, not in separate calls
• Use schema-level validation alongside MongoDB server validation
• Use lean() for read-only queries (returns plain objects, not Mongoose documents)

Middleware Order

1. validate → save → remove (document middleware)
2. find → findOne → findOneAndUpdate (query middleware)
3. aggregate (aggregate middleware)

Discriminators (Polymorphism)

const paymentSchema = new Schema({ amount: Number, currency: String });
const Payment = mongoose.model('Payment', paymentSchema);

const CreditCardPayment = Payment.discriminator('CreditCard',
  new Schema({ cardNumber: String, expiry: String }));
const BankTransfer = Payment.discriminator('BankTransfer',
  new Schema({ accountNumber: String, routingNumber: String }));

Motor (Python Async)

Best Practices

• Use to_list(length=N) with bounded length — never to_list(length=None) on large collections
• Use motor.motor_asyncio.AsyncIOMotorClient for async operations
• Configure connection pool: maxPoolSize, minPoolSize, maxIdleTimeMS
• Use codec_options for automatic type conversion

MongoDB .NET Driver

Repository Pattern

public class OrderRepository
{
    private readonly IMongoCollection<Order> _collection;

    public OrderRepository(IMongoDatabase database)
    {
        _collection = database.GetCollection<Order>("orders");
    }

    public async Task<Order?> GetByIdAsync(string id)
    {
        return await _collection.Find(o => o.Id == id).FirstOrDefaultAsync();
    }

    public async Task CreateAsync(Order order)
    {
        await _collection.InsertOneAsync(order);
    }
}

LINQ Queries

var results = await _collection.AsQueryable()
    .Where(o => o.Status == OrderStatus.Pending)
    .OrderByDescending(o => o.CreatedAt)
    .Take(20)
    .ToListAsync();

migrate-mongo

Best Practices

• One migration per logical change
• Always implement both up and down
• Use db.collection() not model imports (framework-agnostic)
• Test migrations against a copy of production data
• Name files descriptively: add-customer-status-index, backfill-email-verified