Flask app boilerplate with SQLAlchemy and Alembic

Overview

This project includes the basic boilerplate required to integrate SQLAlchemy with Flask. Alembic database upgrading is included. Flask-SQLAlchemy extension is not used: Among other things, a custom base class for SQLAlchemy declarative models that creates a dependency on Flask is therefore not required.

Installation

These instructions may be Ubuntu linux-specific in some places. Python 3.6+ and pipenv are required.

• create env.sh file and add the following environment variables (substitute ~/dev/flask_sqlalchemy_starter , username, userpassword, server, and dbname accordingly):

export PYTHONPATH=~/dev/flask_sqlalchemy_starter 
export SQLALCHEMY_USERNAME=username
export SQLALCHEMY_PASSWORD=userpassword
export SQLALCHEMY_SERVER=server
export SQLALCHEMY_DBNAME=dbname
export SQLALCHEMY_URL="postgresql://$SQLALCHEMY_USERNAME:$SQLALCHEMY_PASSWORD@$SQLALCHEMY_SERVER/$SQLALCHEMY_DBNAME"

You don't have to use postgresql as the db of course.

• If you wish to use slite in memory, set SQLALCHEMY_URL to "sqlite://" (see env_test.sh)
• If you want to use postgresql and it's not installed on your system yet, I've included instructions for postgresql installation on Ubuntu linux at the end of this file.

• start python virtual environment: $ pipenv shell
• install: $ pipenv install
• install with dev dependencies (unit testing): $ pipenv install --dev
• run: $ source env.sh && FLASK_ENV=development flask run
  • http://localhost:5000/ should show json greeting
  • http://localhost:5000/messages should show json list of messages
• run tests: $ source env_test.sh followed by $ pytest -v

Database setup and migration

• $ source env.sh
• $ ./create_db.sh
• cd flask_sqlalchemy_starter && alembic upgrade head && cd ..
• $ psql -a -f populate_db.sql (pre-populates db with a few rows of data)

Install postgresql on Ubuntu

• $ echo "deb http://apt.postgresql.org/pub/repos/apt/ bionic-pgdg main" | sudo tee /etc/apt/sources.list.d/pgdg.list

'bionic' in the above command refers to the codename for ubuntu linux 18.04. Update as required for appropriate linux version

• $ wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -
• $ sudo apt-get install postgresql-10 pgadmin4

You can omit pgadmin4 if you don't want to use it.

Create a db user corresponding to your linux username and give that user a db password (not the same as your linux password):

• $ sudo -u postgres createuser -s "$SQLALCHEMY_USERNAME"
• $ psql -a -f update_user_password.sql