app.py

import os
from flask_jwt_extended.jwt_manager import JWTManager
from flask import Flask, jsonify
from flask_smorest import Api
from resources.item import blue_print as item_blueprint
from resources.store import blue_print as store_blueprint
from resources.tag import blue_print as tag_blueprint
from resources.user import blue_print as user_blueprint
from db import db
from blocklist import expired_tokens
from flask_migrate import Migrate


def create_app(db_url=None):
    app = Flask(__name__)

    app.config['PROPAGATE_EXCEPTIONS'] = True
    app.config['API_TITLE'] = 'Stores REST API'
    app.config['API_VERSION'] = 'v1'
    app.config['OPENAPI_VERSION'] = '3.0.3'
    app.config['OPENAPI_URL_PREFIX'] = '/'
    app.config['OPENAPI_SWAGGER_UI_PATH'] = '/swagger-ui'
    app.config['OPENAPI_SWAGGER_UI_URL'] = 'https://cdn.jsdelivr.net/npm/swagger-ui-dist/'
    app.config['SQLALCHEMY_DATABASE_URI'] = db_url or os.getenv('DATABASE_URL', 'sqlite:///data.db')
    app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
    # Connect flask app to SQLAlchemy
    db.init_app(app)
    migrate = Migrate(app, db)
    api = Api(app)

    # JWT uses secret key to verify that a jwt has been generated by our api
    app.config['JWT_SECRET_KEY'] = os.getenv('jwt_secret_key', 'DummySecretKey')
    jwt = JWTManager(app)

    @jwt.token_in_blocklist_loader
    def check_if_token_in_blocklist(jwt_header, jwt_payload):
        return jwt_payload['jti'] in expired_tokens

    # Customizing JWT frequent error messages for the user
    @jwt.expired_token_loader
    def expired_token_callback(jwt_header, jwt_payload):
        return jsonify({
            "Message": "The token has expired.",
            "error": "token_expired"
        }), 401

    @jwt.invalid_token_loader
    def invalid_token_callback(error):
        return jsonify({"Message": "Signature verification failed.", "error": "Invalid Token"}), 401

    @jwt.unauthorized_loader
    def missing_token_callback(error):
        return jsonify({"description": "Request does not contain an access token",
                        "error": "authorization_required"}), 401

    @jwt.revoked_token_loader
    def revoked_token_callback(jwt_header, jwt_payload):
        return jsonify({"description": "The token has been revoked", "error": " token_revoked"}), 401

    @jwt.needs_fresh_token_loader
    def token_not_fresh_callback(jwt_header, jwt_payload):
        return jsonify({"description": "The token is not fresh.", "error": "fresh_token_required"}), 401

    # Create all models
    with app.app_context():
        db.create_all()

    # register all our APIs
    api.register_blueprint(item_blueprint)
    api.register_blueprint(store_blueprint)
    api.register_blueprint(tag_blueprint)
    api.register_blueprint(user_blueprint)

    return app