This is an example of how to build a RESTful API that performs CRUD operations on a Postgres database using Flask and the extension, Flask-RESTful. The particular application is creating a to-do list.

todo.py - Defines the flask app, and the Flask RESTful api endpoints defined on top of it
models.py - Defines the data model, implemented with the Flask SQLAlchemy ORM
tests.py - Testing of API endpoints using Python unittest module

To access the api from the command line:

GET request (for task with id 1):

curl http://localhost:5000/todo/1

POST request:

curl http://localhost:5000/todo/ -X POST -H "Content-Type:application/json" -d '{"name":"Clean apartment","description":"Sweep, Mop, Tidy"}'

Designing a RESTful API using Flask-RESTful
This is Part 3 of a 3-part blog post by @miguelgrinberg on designing RESTful API's with Flask. This particular post was useful for explaining how the Flask-RESTful extension differs from using base Flask and demonstrating the additional functionality it brings. There are github links in the article to an API built with both Flask and Flask-RESTful. https://blog.miguelgrinberg.com/post/designing-a-restful-api-using-flask-restful

Test Driven Development of a Flask API
This is a great blog post that uses Flask-RESTful, sqlalchemy, postgres, and the nose testing framework to demonstrate how to write and test a simple API that performs CRUD operations. This was a really helpful example, though in my implementation I used the python unittest module over nose, and made use of field and marshal functionality in Flask-RESTful. http://mkelsey.com/2013/05/15/test-driven-development-of-a-flask-api/

Flask-RESTful documentation
Definitely read through the docs before building your own API. Start with the quickstart API and then move on to using argument parsing and field marshaling. Be aware that the API reference page is currently empty, and that there are other typos in the docs. Also, the reqparse functionality is being deprecated in favor of the external marshmallow package. I found that there weren't enough examples in the docs to figure out how to fit all of the components together in one app, but the docs were useful to refer to after looking at other examples. https://flask-restful.readthedocs.io/en/0.3.5/quickstart.html#full-example