I'm trying to use PyMongo in a type safe(ish) way in VS Code. I've tried following the type hints section in the PyMongo documentation and arrived at the following (app is a Flask instance):
from typing import Any, TypedDict
from pymongo import MongoClient
from app import app
from pymongo.collection import Collection
class Movie(TypedDict):
title: str
genres: list[str]
def get_db():
conn_string = str(app.config['MONGO_URI'])
return MongoClient[dict[str, Any]](conn_string)
@app.route('/test')
def models():
client = get_db()
db = client['sample_mflix']
coll: Collection[Movie] = cast(Collection[Movie], db['movies'])
genres = list(coll.aggregate([
{"$unwind": "$genres"},
{"$group": {"_id": None, "genres": {"$addToSet": "$genres"}}}
]))[0]['genres']
return make_response(jsonify(genres), 200)
I realize that the error stems from the fact that I've typed db to be dict[str, Any], so the type of the collection is Collection[dict[str, Any]] requiring a cast to the type (Movie). I could get around this if typed the client as MongoClient[Movie], but presumably, I will want to interact with collections other than the movies collection.
Should I make a client per collection? Live with the cast? Some other pattern I'm missing?
