Boilerplate Flask Apps

Reference codebase used in all Flask Apps provided by the AppSeed platform

All Flask Apps generated by AppSeed share the same codebase structure and features

• Reference Codebase - Flask Apps Boilerplate

• SQLite database, Flask-SQLAlchemy ORM

• Session-Based auth flow (login, register)

• Deployment scripts: Docker, Gunicorn / Nginx, Heroku

✨ Environment

To use the starter, Python3 should be installed properly in the workstation. If you are not sure if Python is installed, please open a terminal and type python --version. Here is the full list with dependencies and tools required to build the app:

• Python3 - the programming language used to code the app

• GIT - used to clone the source code from the Github repository

• Basic development tools (g++ compiler, python development libraries ..etc) used by Python to compile the app dependencies in your environment.

• (Optional) Docker - a popular virtualization software

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✨ Start the app in Docker

👉 Step 1 - Download the code from the GH repository (using GIT)

$ # Get the code
$ git clone https://github.com/app-generator/boilerplate-code-flask.git
$ cd boilerplate-code-flask

👉 Step 2 - Start the APP in Docker

$ docker-compose up --build 

Visit http://localhost:5085 in your browser. The app should be up & running.

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✨ Manual Build

Download the code

$ # Get the code
$ git clone https://github.com/app-generator/boilerplate-code-flask.git
$ cd boilerplate-code-flask

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👉 Set Up for Unix, MacOS

Install modules via VENV

$ virtualenv env
$ source env/bin/activate
$ pip3 install -r requirements.txt

Set Up Flask Environment

$ export FLASK_APP=run.py
$ export FLASK_ENV=development

Start the app

$ flask run

At this point, the app runs at http://127.0.0.1:5000/.

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👉 Set Up for Windows

Install modules via VENV (windows)

$ virtualenv env
$ .\env\Scripts\activate
$ pip3 install -r requirements.txt

Set Up Flask Environment

$ # CMD 
$ set FLASK_APP=run.py
$ set FLASK_ENV=development
$
$ # Powershell
$ $env:FLASK_APP = ".\run.py"
$ $env:FLASK_ENV = "development"

Start the app

$ flask run

At this point, the app runs at http://127.0.0.1:5000/.

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✨ Manage App Users

By default, the starter is not provided with users.

👉 Create Users

By default, the app redirects guest users to authenticate. In order to access the private pages, follow this set up:

• Start the app via flask run

• Access the registration page and create a new user:

  • http://127.0.0.1:5000/register

• Access the sign in page and authenticate

  • http://127.0.0.1:5000/login\

✨ Codebase structure

The project is coded using a simple and intuitive structure presented below:

< PROJECT ROOT >
   |
   |-- apps/
   |    |
   |    |-- home/                           # A simple app that serve HTML files
   |    |    |-- routes.py                  # Define app routes
   |    |
   |    |-- authentication/                 # Handles auth routes (login and register)
   |    |    |-- routes.py                  # Define authentication routes  
   |    |    |-- models.py                  # Defines models  
   |    |    |-- forms.py                   # Define auth forms (login and register) 
   |    |
   |    |-- static/
   |    |    |-- <css, JS, images>          # CSS files, Javascripts files
   |    |
   |    |-- templates/                      # Templates used to render pages
   |    |    |-- includes/                  # HTML chunks and components
   |    |    |    |-- navigation.html       # Top menu component
   |    |    |    |-- footer.html           # App Footer
   |    |    |    |-- scripts.html          # Scripts common to all pages
   |    |    |
   |    |    |-- layouts/                   # Master pages
   |    |    |    |-- base-fullscreen.html  # Used by Authentication pages
   |    |    |    |-- base.html             # Used by common pages
   |    |    |
   |    |    |-- accounts/                  # Authentication pages
   |    |    |    |-- login.html            # Login page
   |    |    |    |-- register.html         # Register page
   |    |    |
   |    |    |-- home/                      # UI Kit Pages
   |    |         |-- index.html            # Index page
   |    |         |-- page-404.html         # 404 page
   |    |         |-- *.html                # All other pages
   |    |    
   |  config.py                             # Set up the app
   |    __init__.py                         # Initialize the app
   |
   |-- requirements.txt                     # App Dependencies
   |
   |-- .env                                 # Inject Configuration via Environment
   |-- run.py                               # Start the app - WSGI gateway
   |
   |-- ************************************************************************

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✨ Application Bootstrap Flow

The entry point of the project is the run.py file where the project configuration is bundled. The most important files that make the project functional are listed below:

• run.py is the application entry point

  • read the Debug flag from .env

  • import the db object from apps package

  • import the create_app helper from apps

• Flask application is built by create_app

  • If Debug=True - SQLite is used (development mode)

  • If Debug=False - SQLite is used (production mode)

• Configuration

  • is defined in apps/config.py

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✨ How the Flask App object is constructed

The file that constructs the core features of our application is apps/__init__.py. The most important steps are listed below:

• Invokes SQLAlchemy to build the db object.

  • Using SQLAlchemy we can manage the database information with ease

• Invokes LoginManager to build the login_manager object.

  • login_manager manage the authentication layer (login, logout, register)

• Defines create_app helper that does the following:

  • create the Flask app object

  • injects db and login_manager objects

  • loads the configuration

  • register default blueprints:

    • authentication - handles the authentication routes

    • home - serve all the pages saved in the apps/templates/home folder

  • initialize the database

    • db.create_all() - create all tables

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✨ Application Blueprints

The codebase is built using a modular design that uses blueprints. By default, the project comes with a two blueprints

👉 Authentication Blueprint

Definition: apps/authentication. The core files:

• __init__.py - defines the Blueprint object

• models.py - defines the Users model

• forms.py - defines the Login and Registration forms

• utils.py - helpers used to hass and verify the password

• routes - manages the authentication routes:

  • login

  • register

  • logout

👉 Home Blueprint

This module returns all pages saved in the templates/home directory to authenticated users. In case a page is not found, a generic page is returned using a 404 HTTP error status.

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✨ UI Assets and Templates

The project comes with a modern UI fully migrated and usable with Django Template Engine.

👉 Page Templates

All pages and components are saved inside the apps/templates directory. Here are the standard directories:

• templates/layouts: UI masterpages

• templates/includes: UI components (used across multiple pages)

• templates/accounts: login & registration page

• templates/home: all other pages served via a generic routing by apps/home app

< PROJECT ROOT >
   |
   |-- apps/
   |    |
   |    |-- home/                      # A simple app that serve HTML files
   |    |-- authentication/            # Handles auth routes (login and register)
   |    |
   |    |-- static/
   |    |    |-- <css, JS, images>     # CSS files, Javascripts files
   |    |
   |    |-- templates/                 # Templates used to render pages
   |         |-- includes/             # HTML chunks and components
   |         |    |-- navigation.html  # Top menu component
   |         |    |-- footer.html      # App Footer
   |         |    |-- scripts.html     # Scripts common to all pages
   |         |
   |         |-- layouts/              # Master pages
   |         |    |-- base.html        # Used by common pages
   |         |
   |         |-- accounts/             # Authentication pages
   |         |    |-- login.html       # Login page
   |         |    |-- register.html    # Register page
   |         |
   |         |-- home/                 # UI Kit Pages
   |              |-- index.html       # Index page
   |              |-- page-404.html    # 404 page
   |              |-- *.html           # All other pages
   |
   |-- ************************************************************************

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👉 Static Assets

The static assets used by the project (JS, CSS, images) are saved inside the apps/static/assets folder. This path can be customized with ease via ASSETS_ROOT variable saved in the .env file.

How it works

• .env defines the ASSETS_ROOT variable

• apps/config.py read the value of ASSETS_ROOT and defaults to /static/assets if not found:

# content of apps/config.py (truncated content)

ASSETS_ROOT = os.getenv('ASSETS_ROOT', '/static/assets') 

• All pages and components use the config.ASSETS_ROOT variable. Here is a sample extracted from templates/layouts/base.html:

<head>

    <!-- Source Code -->
    <link rel="stylesheet" href="{{ config.ASSETS_ROOT }}/css/style.css">

    <!-- RUNTIME -->
    <link rel="stylesheet" href="/static/assets/css/style.css">

At runtime, the href property is resolved to /static/assets/css/style.css based on the value saved in the .env file:

# No Slash at the end
ASSETS_ROOT=/static/assets

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✨ Customisation

👉 Set up the MySql Database

Note: Make sure your Mysql server is properly installed and accessible.

Step 1 - Create the MySql Database to be used by the app

• Create a new MySql database

• Create a new user and assign full privilegies (read/write)

Step 2 - Install flask_mysqldb package

$ pip install flask_mysqldb

Step 3 - Edit the .env to match your MySql DB credentials. Make sure DEBUG is set to False.

• DB_ENGINE : mysql

• DB_NAME : default value = appseed_db

• DB_HOST : default value = localhost

• DB_PORT : default value = 3306

• DB_USERNAME: default value = appseed_db_usr

• DB_PASS : default value = pass

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Here is a sample:

# .env sample

DEBUG=False                 # False enables the MySql Persistence

DB_ENGINE=mysql             # Database Driver
DB_NAME=appseed_db          # Database Name
DB_USERNAME=appseed_db_usr  # Database User
DB_PASS=STRONG_PASS_HERE    # Password 
DB_HOST=localhost           # Database HOST, default is localhost 
DB_PORT=3306                # MySql port, default = 3306 

At this point, the app should use MySql for the persistence layer.

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👉 Static Assets for production

As explained in the Static Assets section, the assets are managed via:

• apps/static/assets - the folder where JS, CSS, and images files are saved

• ASSETS_ROOT - environment variable, that defaults to /static/assets if not defined

In production, the contents of the apps/static/assets files should be copied to an external (public) directory and the ASSETS_ROOT environment variable updated accordingly.

For instance, if the static files are copied to https://cdn.your-server.com/datta-able-assets, the .env file should be updated as below:

# No Slash at the end
ASSETS_ROOT=https://cdn.your-server.com/datta-able-assets

🚀 Where to go from here

• 👉 Access the support page in case something is missing
• 👉 Use the App Generator to generate a new project