Avoiding Circular Imports in Flask Projects

For avoiding the circular import in flask projects, we do the import at the bottom of our code.
For example, in the routes.py file I have two imports app and db like so:
from app import app, db

• If you import routes at the top of app.py, Python will try to load routes.py before app and db are fully defined.
  - That creates a circular dependency:

• app.py imports routes

• routes.py imports app

• Neither file finishes loading → error or undefined objects.

• By placing import routes at the bottom, you ensure:

• app, db, jwt, and migrate are initialized first.

• Then routes.py can safely attach endpoints to app.

in the app.py file:

`from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_jwt_extended import JWTManager
from flask_migrate import Migrate

Create the Flask application instance

app = Flask(name)

Load configuration settings (e.g., DB URI, JWT secret key) from config.py

app.config.from_object("config.Config")

Initialize SQLAlchemy ORM with the app

db = SQLAlchemy(app)

Initialize JWT manager for authentication

jwt = JWTManager(app)

Initialize Flask-Migrate for database migrations

migrate = Migrate(app, db)

Custom CLI command: create all database tables

@app.cli.command("db_create")
def db_create():
db.create_all()
print("db created!.")

Custom CLI command: drop all database tables

@app.cli.command("db_drop")
def db_drop():
db.drop_all()
print("db dropped!.")

Import routes AFTER app, db, jwt, migrate are defined

This avoids circular imports (routes.py needs app and db)

import routes`

in the routes.py file:

`from flask import jsonify, request
from flask_jwt_extended import jwt_required, get_jwt_identity
from app import db
from app.models import Post

def register_routes(app):
@app.route("/v1/post", methods=["POST"])
@jwt_required()
def add_post():
user_id = int(get_jwt_identity())
data = request.get_json()
post = Post(title=data["title"], body=data["body"], author_id=user_id)
db.session.add(post)
db.session.commit()
return jsonify(message="Post created successfully"), 201`