MontyDB

2.5.6 verified Fri May 01 auth: no python

Monty, Mongo tinified. MongoDB implemented in Python. Current version 2.5.6, supports Python >=3.7. Released irregularly.

pip install montydb

Common errors

error ModuleNotFoundError: No module named 'monty' ↓

cause Incorrect import; users attempt 'import monty' instead of 'montydb'.

fix

Run 'pip install montydb' and use 'from montydb import MontyClient'.

error pymongo.errors.ServerSelectionTimeoutError: No primary server found ↓

cause Using pymongo's MongoClient with MontyDB's connection string. MontyDB does not start a real MongoDB server.

fix

Use MontyClient from montydb, not pymongo's MongoClient.

error NotImplementedError: The 'collStats' command is not supported ↓

cause Attempt to use aggregation pipeline operators not implemented by MontyDB (e.g., $collStats).

fix

Replace unsupported operators with equivalent Python code or use simpler queries.

Warnings

gotcha MontyDB's 'import montydb' is correct, but users often mistakenly import 'monty' or 'montydb.client'. ↓

fix Use 'from montydb import MontyClient' or 'from montydb import connect'.

gotcha MontyDB is not fully compatible with all MongoDB features; aggregation pipelines with unsupported operators may raise NotImplementedError. ↓

fix Check the documentation for supported operators; use native Python logic if needed.

breaking Version 2.5.0 introduced support for mongoengine but changed internal storage engine; existing databases may need migration. ↓

fix Back up your montydb data directory before upgrading, or use in-memory mode temporarily.

gotcha In-memory databases are per-process; they do not persist after restart. Users expecting persistence must specify a storage path. ↓

fix Use MontyClient(repository='path/to/data') for persistent file-based storage.

Imports

MontyClient
wrong
```
from monty import MontyClient
```
correct
```
from montydb import MontyClient
```
'monty' is not a valid module; must use 'montydb'.
connect
wrong
```
from pymongo import MongoClient
```
correct
```
from montydb import connect
```
MontyDB mimics pymongo but is a separate library; using pymongo will connect to a real MongoDB instead.

Quickstart

Create an in-memory database and perform basic CRUD.

from montydb import MontyClient, connect

# Using MontyClient with in-memory storage
client = MontyClient()
db = client.test_db
collection = db.test_collection
collection.insert_one({'name': 'Alice', 'age': 30})
print(collection.find_one({'name': 'Alice'}))