Flask MVC Template

A template for flask applications structured in the Model View Controller pattern Demo

Dependencies

• Python3/pip3
• Packages listed in requirements.txt

Installing Dependencies

$ pip install -r requirements.txt

Configuration Management

Configuration information such as the database url/port, credentials, API keys etc are to be supplied to the application. However, it is bad practice to stage production information in publicly visible repositories. Instead, all config is provided by a config file or via environment variables.

In Development

When running the project in a development environment (such as gitpod) the app is configured via config.py file in the App folder. By default, the config for development uses a sqlite database.

config.py

SQLALCHEMY_DATABASE_URI = "sqlite:///temp-database.db"
SECRET_KEY = "secret key"
JWT_EXPIRATION_DELTA = 7
ENV = "DEVELOPMENT"

In Production

When deploying your application to production/staging you must pass in configuration information via environment variables. For heroku, you need to navigate to your application's setting page (url should look like https://dashboard.heroku.com/apps/[app-name]/settings) and scroll down to config vars. Then provide your configuration by defining the same values given in config.py

When deploying to production the "ENV" variable should be set to "PRODUCTION".

Note heroku provides a default variable "DATABASE_URL" for heorku postgres. If you want the app to use this database you must copy the value to the variable "SQLALCHEMY_DATABASE_URL" and change the protocol to "postgresql://" for sqlalchemmy.

Flask Commands

wsgi.py is a utility script for performing various tasks related to the project. You can use it to import and test any code in the project. You just need create a manager command function, for example:

# inside wsgi.py


@app.cli.command("create-user")
@click.argument("username")
@click.argument("password")
def create_user_command(username, password):
    create_user(username, password)
    print(f'{username} created!')
    

Then execute the command invoking with flask cli with command name and the relevant parameters

$ flask create-user bob bobpass

Running the Project

For development run the serve command (what you execute):

$ flask run

For production using gunicorn (what heroku executes):

$ gunicorn App.main:app

Deploying

You can deploy your version of this app to heroku by clicking on the "Deploy to heroku" link above.

Initializing the Database

When connecting the project to a fresh empty database ensure the appropriate configuration is set then file then run the following command. This must aslo be executed once when running the app on heroku by opening the heroku console, executing bash and running the command in the dyno.

$ flask init

Database Migrations

If changes to the models are made, the database must be'migrated' so that it can be synced with the new models. Then execute following commands using manage.py. More info here

$ flask db init
$ flask db migrate
$ flask db upgrade
$ flask db --help