[SOLVED] How to pass database session to Ariadne in Fastapi

How to pass database session to Ariadne in Fastapi

I'm new to python, trying to learn and use Fastapi, Ariadne and SQLAlchemy. I'm following the docs and I'm stuck.

I have my dependency injection get_db() for normal REST requests, which provides a Session object, which I pass through few different modules from the request start until I actually do the db work, and honestly I don't get this design. But I left it there.

Then, another problem come up. How can I pass db to Ariadne GraphQL? Should I use context_value or are there any other options?

Solution

You need to create a session of SQLAlchemy from ariadne resolvers. And don't forget to close the connection after resolvers finished.

Let's say your database file like following,

import os

from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker

SQLALCHEMY_DATABASE_URL = os.getenv("DB_CONN_STRING")

engine = create_engine(SQLALCHEMY_DATABASE_URL)
LocalSession = sessionmaker(autocommit=False, autoflush=False, bind=engine)

def get_db():
    db = None
    try:
        db = LocalSession()
        yield db
    finally:
        if db:
            db.close()

You can do like following on the resolvers

# Import the local session from local database file
from app.database import LocalSession

db = LocalSession()
# Do whatever you need to do
db.close()