Boilerplate Flask Dashboards

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

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

  • Reference Codebase - Flask Dashboard Boilerplate

  • DBMS: SQLite, PostgreSQL (production)

  • DB Tools: SQLAlchemy ORM, Flask-Migrate (schema migrations)

  • Modular design with Blueprints

  • Session-Based authentication (via flask_login), Forms validation

  • Deployment scripts: Docker, Gunicorn / Nginx, HEROKU

Links

Support (Email and LIVE on Discord) for registered AppSeed users.

Environment

To use the stater, Python3 should be installed properly in the workstation. If you are not sure if Python is properly installed, please open a terminal and type python --version. 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.

Build the app

To built and start the app locally, follow the steps:

Get the source code

  • Download the ZIP from Github Repository

  • Using GIT tool in the terminal to clone the source code

Change the current directory to source code directory

$ # Make sure you are running the commands INSIDE source code directory
$
$ # Virtualenv modules installation (Unix based systems)
$ virtualenv env
$ source env/bin/activate
$
$ # Virtualenv modules installation (Windows based systems)
$ # virtualenv env
$ # .\env\Scripts\activate
$
$ # Install modules - SQLite Database
$ pip3 install -r requirements.txt
$
$ # OR with PostgreSQL connector
$ # pip install -r requirements-pgsql.txt
$
$ # Set the FLASK_APP environment variable
$ (Unix/Mac) export FLASK_APP=run.py
$ (Windows) set FLASK_APP=run.py
$ (Powershell) $env:FLASK_APP = ".\run.py"
$
$ # Set up the DEBUG environment
$ # (Unix/Mac) export FLASK_ENV=development
$ # (Windows) set FLASK_ENV=development
$ # (Powershell) $env:FLASK_ENV = "development"
$
$ # Start the application (development mode)
$ # --host=0.0.0.0 - expose the app on all network interfaces (default 127.0.0.1)
$ # --port=5000 - specify the app port (default 5000)
$ flask run --host=0.0.0.0 --port=5000
$
$ # Access the dashboard in browser: http://127.0.0.1:5000/

App Codebase (simplified)

Starter uses a simple codebase (no Blueprints) with a structure presented bellow:

< PROJECT ROOT >
|
|-- app/ # Implements app logic
| |-- base/ # Base Blueprint - handles the authentication
| |-- home/ # Home Blueprint - serve UI Kit pages
| |
| __init__.py # Initialize the app
|
|-- requirements.txt # Development modules - SQLite storage
|-- requirements-mysql.txt # Production modules - Mysql DMBS
|-- requirements-pqsql.txt # Production modules - PostgreSql DMBS
|
|-- .env # Inject Configuration via Environment
|-- config.py # Set up the app
|-- run.py # Start the app - WSGI gateway
|
|-- ************************************************************************

The bootstrap flow

  • run.py loads the .env file

  • Initialize the app using the specified profile: Debug or Production

    • If env.DEBUG is set to True the SQLite storage is used

    • If env.DEBUG is set to False the specified DB driver is used (MySql, PostgreSQL)

  • Call the app factory method create_app defined in app/init.py

  • Redirect the guest users to Login page

  • Unlock the pages served by home blueprint for authenticated users

.env (saved in the root of the project)

# File: `.env`
DEBUG=True # Enable/Disable the development environment
SECRET_KEY=S3cr3t_Key # The Key used by Flask to encrypt session information
# Database production settings (If DEBUG=False)
DB_ENGINE=postgresql # DBMS
DB_NAME=appseed-flask # Database Name
DB_HOST=localhost # Database Host
DB_PORT=5432 # Database Port
DB_USERNAME=appseed # DB Username
DB_PASS=pass # DB Password

run.py (simplified version)

# File: run.py
DEBUG = config('DEBUG', default=True)
# Create the WSGI app, using the app factory pattern
app = create_app( app_config )
# Migrate automaticaly the app using Flask Migrate library
Migrate(app, db)

app/__init__.py (simplified version)

# File: app/__init__.py
db = SQLAlchemy() # Invoke SQLAlchemy
login_manager = LoginManager() # Invoke Login Manager
def register_extensions(app):
db.init_app(app) # Inject SQLAlchemy magic
login_manager.init_app(app) # Add Login Manager to the app
# Register app blueprints: `base`, `home`
def register_blueprints(app):
for module_name in ('base', 'home'):
module = import_module('app.{}.routes'.format(module_name))
app.register_blueprint(module.blueprint)
# Create the tables (automaticaly)
def configure_database(app):
@app.before_first_request
def initialize_database():
db.create_all()
# Create the WSGI app using the factory pattern
def create_app(config):
app = Flask(__name__, static_folder='base/static')
app.config.from_object(config)
register_extensions(app)
register_blueprints(app)
configure_database(app)
return app

The app/__init__.py constructs the app by putting together a short-list of things:

  • Invoke SQLAlchemy

  • Invoke and inject the Login Manager into the app

  • Load the configuration from config.py file

  • Register the app blueprints

  • Check if the database tables are created

  • return the WSGI app

App Codebase

The starter defines two blueprints:

  • Base blueprint - handles the authentication (routes and forms) and assets management

  • Home blueprint - serve HTM pages for authenticated users

App / Base Blueprint structure

< PROJECT ROOT >
|
|-- app/
| |-- home/ # Home Blueprint - serve app pages (private area)
| |-- base/ # Base Blueprint - handles the authentication
| |-- static/
| | |-- <css, JS, images> # CSS files, Javascripts files
| |
| |-- templates/ # Templates used to render pages
| |
| |-- includes/ #
| | |-- navigation.html # Top menu component
| | |-- sidebar.html # Sidebar 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 # Registration page
|
|-- requirements.txt # Development modules - SQLite storage
|-- requirements-mysql.txt # Production modules - Mysql DMBS
|-- requirements-pqsql.txt # Production modules - PostgreSql DMBS
|
|-- .env # Inject Configuration via Environment
|-- config.py # Set up the app
|-- run.py # Start the app - WSGI gateway
|
|-- ************************************************************************

App / Home Blueprint structure

< PROJECT ROOT >
|
|-- app/
| |-- base/ # Base Blueprint - handles the authentication
| |-- home/ # Home Blueprint - serve app pages (private area)
| |
| |-- templates/ # UI Kit Pages
| |
| |-- index.html # Default page
| |-- page-404.html # Error 404 - mandatory page
| |-- page-500.html # Error 500 - mandatory page
| |-- page-403.html # Error 403 - mandatory page
| |-- *.html # All other HTML pages
|
|-- requirements.txt # Development modules - SQLite storage
|-- requirements-mysql.txt # Production modules - Mysql DMBS
|-- requirements-pqsql.txt # Production modules - PostgreSql DMBS
|
|-- .env # Inject Configuration via Environment
|-- config.py # Set up the app
|-- run.py # Start the app - WSGI gateway
|
|-- ************************************************************************

App Configuration

The configuration file config.py (in the root of the project) define a dual configuration controlled via the .env file ( DEBUG variable)

DebugConfig - default configuration used for development

This configuration becomes active if .env file has the DEBUG file set to True

# Development/Debug configuration
# Set up the App SECRET_KEY
SECRET_KEY = config('SECRET_KEY', default='S#perS3crEt_007')
# This will create a file in <app> FOLDER
SQLALCHEMY_DATABASE_URI = 'sqlite:///' + os.path.join(basedir, 'db.sqlite3')
SQLALCHEMY_TRACK_MODIFICATIONS = False

During the first request, the SQLite database and tables are automatically created in the root in the project.

Hint: to visualize the SQLite database content an external tool should be installed: DB Browser for SQLite it might be a good choice.

ProductionConfig - production configuration

This configuration becomes active if .env file has the DEBUG file set to False

# Production configuration
SESSION_COOKIE_HTTPONLY = True
REMEMBER_COOKIE_HTTPONLY = True
REMEMBER_COOKIE_DURATION = 3600
# PostgreSQL database
SQLALCHEMY_DATABASE_URI = '{}://{}:{}@{}:{}/{}'.format(
config( 'DB_ENGINE' , default='postgresql' ),
config( 'DB_USERNAME' , default='appseed' ),
config( 'DB_PASS' , default='pass' ),
config( 'DB_HOST' , default='localhost' ),
config( 'DB_PORT' , default=5432 ),
config( 'DB_NAME' , default='appseed-flask' )
)

In this configuration profile, the database defaults to a PostgreSQL DBMS. Make sure the .env has the right credentials to access the database.

App Tables

The file app/base/models.py (Base Blueprint) defines the table(s) used by the application. Being a simple starter, by default the following tabes are defined:

  • Table #1 - User with fields:

    • Id - Primary key, unique

    • user - Store the username

    • email - The email address

    • password - Hashed password

App Forms

The file app/base/forms.py (Base Blueprint) defines the table(s) used by the application. Being a simple starter, by default the following forms are defined:

  • Form #1 - LoginForm with fields:

    • username

    • password

  • Form #2 - RegisterForm with fields:

    • username - used to authenticate

    • email - email address

    • password - used to authenticate

App Routing

The routing rules are defined by Base and Home blueprints as specified below. This is the public zone of the app.

Base Blueprint - routing file app/base/routes.py

  • /login route is resolved by login() method

  • /register route is resolved by register() method

  • /logout route calls the logout_user() defined in flask_login

Registered ERROR handlers

  • 404 Error - Page not found

  • 403 Error - Access Forbidden

  • 500 Error - Internal Error

Home Blueprint - routing file app/home/routes.py

This blueprint will serve requested pages from app/home/templates directory to authenticated users. The authentication status is checked by @login_required decorator.

  • /<template> route resolved by route_template().

    • If a requested page is not found a default 404 page is returned to the user

Pages & Assets

Pages and all assets defined in the UI Kits are served by the app using both blueprints:

  • Home Blueprint manage the static assets - app/base/static/assets

  • Home Blueprint store the layout master pages, HTML chunks (footer. header, scripts) and login, registration pages

  • Base Blueprint serve the HTML pages (index, page-404, etc) and the rest of the pages defined in the UI kit.

< PROJECT ROOT >
|
|-- app/
| |-- base/ # Base Blueprint
| | |-- static/assets/
| | | |-- css/ # UI Kit css
| | | |-- JS/ # Javascript files
| | | |-- images/ # images used by the app
| | | |-- scss/ # SCSS files (if any)
| | |
| | |-- templates/ # Templates used to render pages
| | |
| | |-- includes/ #
| | | |-- navigation.html # Top menu component
| | | |-- sidebar.html # Sidebar 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 # Registration page
| |
| |-- home/ # Home Blueprint - serve app pages (private area)
| |-- templates/ # UI Kit Pages
| |
| |-- index.html # Default page
| |-- page-404.html # Error 404 - mandatory page
| |-- page-500.html # Error 500 - mandatory page
| |-- page-403.html # Error 403 - mandatory page
| |-- *.html # All other HTML pages
|
|-- ************************************************************************

Data Structures

The Flask starter exposes a short-list with data structures used globally across the app:

current_user object

Constructed by Flask-Login can be used to detect if the current request is executed by an authenticated user or not. The object has global visibility and can be used in all app controllers and handlers but also in views.

How it works

app/base/models.py define the callback functions required by Flask-Login library:

# File: app/base/models.py
@login_manager.user_loader
def user_loader(id):
return User.query.filter_by(id=id).first()
@login_manager.request_loader
def request_loader(request):
username = request.form.get('username')
user = User.query.filter_by(username=username).first()
return user if user else None

Usage in contoler (Sample file)

def sample_method(path):
# Redirect guests users to login page
if not current_user.is_authenticated:
return redirect(url_for('login'))

Usage in view

<div class="collapse navbar-collapse" id="navigation">
<ul class="navbar-nav ml-auto">
<!-- The Usage of <current_user> object -->
{% if current_user.is_authenticated %}
<!-- Html chunk rendered for authenticated users-->
<li class="nav-item">
<a href="/" class="nav-link text-primary">
<i class="tim-icons icon-minimal-left"></i> Back to Dashboard
</a>
</li>
{% else %}
<!-- Html chunk rendered for guests users-->
<li class="nav-item ">
<a href="{{ url_for('register') }}" class="nav-link">
<i class="tim-icons icon-laptop"></i> Register
</a>
</li>
<li class="nav-item ">
<a href="{{ url_for('login') }}" class="nav-link">
<i class="tim-icons icon-single-02"></i> Login
</a>
</li>
{% endif %}
</ul>
</div>