Here’s the step-by-step approach of how to deploy your Dash app on Pythonanywhere.com using Flask and pip:
- Flask Cheat Sheet by shribee - Cheatography.com Created Date: 0107Z.
- Flask is a popular Python framework for developing web applications. It comes with minimal built-in functionalities and requirements, making it simple to get started and flexible to use. The developer has the liberty to customize most aspects of the app, including database integration, accounts and authentication, and more.
- Flask Cheat Sheet A cheat-sheet for creating web apps with the Flask framework using the Python language.
View flaskcheatsheet.pdf from CS MISC at Kabarak University. #Flask Cheat Sheet and Quick Reference #Barebones App #Access Request Data from flask import Flask request.args'name' #query string.
- Create an account on Pythonanywhere.com.
- Create a Flask application.
- Create a Dash application.
- Copy the Dash app into the Flask app.
- Connect the Flask server with the Dash app.
- Modify the WSGI configuration file.
- Install Dash with pip in your bash shell (e.g.,
pip3.7 install dash --user
) - Refresh your Flask server.
How to Integrate Dash with Your Existing App
Do you have an existing non-dash app and you want to integrate a dashboard within it?
Disclaimer: If you ask me, this isn’t the best idea. Can’t you keep your website clean and simple? One page for one intent. Do you really have to integrate a full-fledged Dash application within this particular web app? Before you answer: yes!, please consider the following: you can always embed interactive graphs with JavaScript.
For instance, a great alternative would be CanvaJS. I’m not affiliated with those guys but they created a great framework that can be used on any website. Heck, you could even use Plotly graphs on your website to visualize data. (These are the creators of Dash.)
The reason why I don’t advocate to use dash in your existing (HTML/CSS/JS) application is that it’s tedious, error prone, and it slows down your website.
I’ll give you three ways—ordered by difficulty:
1 – Place Links Intelligently
Believe it or not, I came up with this genius strategy all by myself. Instead of integrating your app with Dash, you just link to your separate (independent) Dash app so that it appears like the two websites (your original and the Dash app) are working together and are tightly integrated. However, they’re running independently and you can avoid all the struggles and keep living the simple life.
2 – Use iFrames
On the official Dash site to this issue, they recommend to use an
<iframe
>. An iFrame is an HTML element that allows you to embed any website Y on website X. It’s like a window into the other website. On page X, you can define the size of the window and the environment around the window. But you can control little more.While this may work theoretically, it often slows down websites and causes security issues. Some web browsers block the use of iFrames altogether. So, it may happen that users don’t even see your great Dash application!
Do you still want to try it with iFrames? Okay, so go for it:
- Include an
<iframe>
element in your HTML site. - Point the
src
attribute towards the address of your Dash app. - Place your Dash app iFrame within your website defining your desired dimensions:
Here’s how such an embedded iFrame Dash app looks on the Finxter website:
It doesn’t look pretty, does it?
Using an Existing Flask App
Yes, all the programmers out there are salivating. It’s just beautiful to natively integrate two apps, isn’t it? Well, if you think so. I think, it’s a big mess and you’ll curse yourself for doing it. However, if you must do it, here’s how you can do it (based on this resource and the docs):
Access the Flask app via
app.server
and assign it to a variable (e.g., server
).As an alternative, pass your Flask app instance into Dash when instantiating the app in the
dash.Dash(...)
initialization routine.What did you accomplish? The
server
variable now holds the Flask instance. This allows you to add any route and custom functionality like this:You can see such an example in the code given here:
But the authors of the code share the same disclaimer: it sucks! You lose a lot of integrated Flask functionality when working from inside Dash like this.
Maybe go back to method 1? A better way is to use Dash from inside Flask—instead of using Flask from inside Dash. You can see how this works here (scroll down to the heading “Combining One or More Dash Apps with Existing WSGI Apps”).
While working as a researcher in distributed systems, Dr. Christian Mayer found his love for teaching computer science students.
To help students reach higher levels of Python success, he founded the programming education website Finxter.com. He’s author of the popular programming book Python One-Liners (NoStarch 2020), coauthor of the Coffee Break Python series of self-published books, computer science enthusiast, freelancer, and owner of one of the top 10 largest Python blogs worldwide.
His passions are writing, reading, and coding. But his greatest passion is to serve aspiring coders through Finxter and help them to boost their skills. You can join his free email academy here.
Related Posts
Flask is a micro framework for python webapp. It’s really useful for creating prototypes and small application focusing on the logic.
Here’s a cheatsheet!
#!/usr/bin/python
# Import Flask
# and md5 algorithm
from flask import Flask
from flask import request, abort
from hashlib import md5
# Import Flask
# and md5 algorithm
from flask import Flask
from flask import request, abort
from hashlib import md5
# Create a new application
app = Flask(__name__)
app = Flask(__name__)
# Bind methods and functions
@app.route(‘/’)
def index():
return ‘Index Page’
@app.route(‘/’)
def index():
return ‘Index Page’
Flask Programming
@app.route(‘/hello’, methods = [‘GET’, ‘POST’])
def hello():
“””Greets the user.”””
# Those are get parameters
user, client = map(request.args.get, [‘user’, ‘client’])
return ‘Hello %s!’ % user
def hello():
“””Greets the user.”””
# Those are get parameters
user, client = map(request.args.get, [‘user’, ‘client’])
return ‘Hello %s!’ % user
Flask Sqlalchemy Cheat Sheet Pdf
# do this BEFORE each request
@app.before_request
def authorizer():
“””Authenticate user and password passed via GET or POST.
In this sample the password is the md5(user).
Use the abort function to raise an http error!
“””
params = [‘user’, ‘client’,’passwd’,’algorithm’]
user, client, passwd, algorithm = map(request.values.get, params)
if passwd != md5(user).hexdigest():
abort(401)
@app.before_request
def authorizer():
“””Authenticate user and password passed via GET or POST.
In this sample the password is the md5(user).
Use the abort function to raise an http error!
“””
params = [‘user’, ‘client’,’passwd’,’algorithm’]
user, client, passwd, algorithm = map(request.values.get, params)
if passwd != md5(user).hexdigest():
abort(401)
@app.errorhandler(401)
def unauthorized(e):
“””Use error handlers to present error pages.”””
return “Unauthorized user”, 404
def unauthorized(e):
“””Use error handlers to present error pages.”””
return “Unauthorized user”, 404
Flask Cheat Sheet Download
# Run the app
if __name__ ‘__main__’:
app.debug = True
app.run(host=’0.0.0.0′, port=9000)
if __name__ ‘__main__’:
app.debug = True
app.run(host=’0.0.0.0′, port=9000)