RESTful API with Flask, Connextion, Marshmallow and Celery

Overview

This is an implementation of RESTful API with Python 3, Flask, Connexion and Marshmallow. Swagger page provides a list of implemented API calls with an ability to test them. Celery runs 2 async tasks.

Data model consists of two entities: a User and a ContactDetail. User has one-to-many relationship with ContactDetails.

SQLite is used as a backend database, it is represented by a single file and does not require any specific configuration.

RESTful API

Connexion framework automagically handles HTTP requests based on OpenAPI Specification (formerly known as Swagger Spec). Connexion allowed to define an OpenAPI specification of this API in api.yml file and then map the endpoints to API Python functions.

Marshmallow is an ORM library that converts complex datatypes, such as objects, to and from native Python datatypes. Unlike Flask-RESTful, which uses dictionaries to define output schemas, marshmallow uses classes defined in models.py. In this case marshmallow helped to produce output data in JSON format.

How to run the app

• Recreate the database if required:

cd {work_folder}/Flask_REST
python create_database.py

• Run unit tests:

cd {work_folder}/Flask_REST
python -m unittest utests.test_api

• Start up Flask server:

cd {work_folder}/Flask_REST
python app.py

• Open your web browser and navigate to:

http://0.0.0.0:5000/api/ui

• Use this Swagger page to browser API methods and test them.
• You can stop the Flask app as Celery calls API functions directly without creating HTTP requests.
• Start Redis:

docker run -d -p 6379:6379 redis

• Start scheduler for Celery tasks:

cd {work_folder}/Flask_REST
celery -A celery_tasks beat --loglevel=info

• Open new terminal and start Celery worker:

cd {work_folder}/Flask_REST
celery -A celery_tasks worker --loglevel=info

• Open users.db file with SQLite browser and observe tables user and contact_detail being updated every 15 seconds.