database.py

from fastapi import Depends
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.declarative import declarative_base

from typing import Annotated

SQLALCHEMY_DATABASE_URL = "sqlite:///./my_todos.db"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
)

# check same thread will check if the thread is same or not
# if not then it will create a new thread
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()


def get_db():
    try:
        db = SessionLocal()
        yield db
    finally:
        db.close()


db_dependency = Annotated[SessionLocal, Depends(get_db)]