How to get up and running in minutes with the lean, scalable, and easy to maintain Python web framework, Flask. Attendees will get to see how Flask acts as the sturdy glue between your database framework, front-end templates and operating system. Keep an eye out for tips/tricks using SQLite, Jinja2, and Werkzeug. Neil is a software developer with a background in 3D graphics programming and management information systems. Presently he's working with Image Engine on feature-film visual effects projects like Teenage Mutant Ninja Turtles, Elysium, Fast & Furious. He's also a co-founder of ComboMash Entertainment, an independent game studio based in Vancouver.

1. IMPORT FLASK
AN INTRODUCTION TO PYTHON’S FRIENDLY
NEIGHBOURHOOD WEB MICROFRAMEWORK.
NEIL GREY
NEIL@COMBOMASH.COM
COMBOMASH ENTERTAINMENT

2. AGENDA
❖ INTRODUCTIONS
❖ GETTING STARTED
❖ OVERVIEW OF PYTHON & MVC
❖ WHY FLASK?
❖ HELLO WORLD!
❖ ROUTING
❖ TEMPLATES
❖ INTERACTIVE COMPONENTS
❖ FORMS, REQUESTS, & AJAX
❖ DATABASE INTEGRATION (SQLITE)
❖ LOGGING IN / SESSIONS
❖ EMAIL SUPPORT

3. INTRODUCTIONS
❖ WHO’S THE LOUD GUY UP FRONT?
❖ PROFESSIONAL PROGRAMMER AT MID-SIZED VISUAL EFFECTS &
GAMING COMPANIES FOR 6 YEARS
❖ HEAVY FOCUS ON SYSTEMS THAT PROMOTE EFFECTIVE
COMMUNICATION & EFFICIENT PROCESSES
❖ CYCLIST, BIKRAMITE, INDEPENDENT GAME DEVELOPER, OPEN-
SOURCE ENTHUSIAST, VEGAN, SELF-DIRECTED INVESTOR,
MARATHONER, BUSINESS OWNER
❖ BEEN WORKING WITH FLASK REGULARLY FOR JUST OVER A YEAR
AND WITH PYTHON FOR LAST 5 YEARS. EXPERIENCE IN WEB TECH
DATING BACK TO MID-90’S.
❖ ASK THE AUDIENCE
❖ WHAT’S YOUR NAME
& WHY ARE YOU HERE TODAY?
❖ EXPERIENCE LEVEL IN PYTHON? WEB DEVELOPMENT?
nataliedeemachine.com

4. GETTING STARTED
❖ OVERVIEW OF PYTHON & MVC
❖ WHY FLASK?
❖ HELLO WORLD!
❖ ROUTING
❖ TEMPLATES

5. LEARN PYTHON IN 10 MINUTES
HTTP://WWW.STAVROS.IO/TUTORIALS/PYTHON/

6. MODEL-VIEW-CONTROLLER (MVC)
❖ THE MODEL
❖ REPRESENTATION OF DATA. USUALLY HAS A STRONG RELATION WITH
THE UNDERLYING DATABASE.
❖ THE VIEW(S)
❖ WHAT IS SHOWN TO THE USER. CAN BE ANY KIND OF USER INTERFACE,
USUALLY HTML PAGES WITH JAVASCRIPT WHEN DEALING WITH THE
WEB.
❖ THE CONTROLS
❖ WHAT OPERATIONS ARE DONE ON THE DATA.
A CLEAN & CONVENIENT WAY TO DESIGN SOFTWARE PROJECTS
INVOLVING USER INTERFACES WHICH PRESENT AND MANIPULATE SETS
OF DATA.

7. WHY FLASK?
❖ SMALL : QUICK TO LEARN AND MASTER
❖ COMPLETE : YOU CAN USE TO DO SERIOUS APPS
❖ LEAN : A SHELL AND A TEXT EDITOR ARE ENOUGH, NO NEED FOR A
CUMBERSOME IDE
❖ IT IS VERY WELL DOCUMENTED
❖ WHY USING A SCRIPTING LANGUAGE LIKE PYTHON FOR A WEB
APPLICATION?
❖ ADAPTED LANGUAGE WHICH EASILY SUPPORTS PASTING TOGETHER
VARIOUS COMPONENTS (DATABASE, RENDERING, ROUTING, . . . )
❖ MAKES ITS EASIER TO RELEASE EARLY & OFTEN (DEVOPS)
❖ EASIER TO MAINTAIN & MODIFY
❖ SPEED GOOD ENOUGH FOR MANY USE CASES

8. FLASK: HELLO WORLD!
• RUN SCRIPT VIA COMMAND-LINE: PYTHON RUN.PY
• GO TO: 127.0.0.1:5000 TO REVIEW

9. FLASK: ROUTING
Flask uses dynamic pathing to
match user requests to server-
side responses. This is in direct
contrast to a language like PHP
which primarily uses directory-
based pathing to locate files
containing called-upon
functionality.
This is extremely useful since we
can pass variables into our
dynamic paths so not to duplicate
functionality across multiple files,
and still have a human-readable
URL.

10. FLASK: ROUTING
Status Code Type
400 Bad Request
401 Unauthorized
402 Payment Required
403 Forbidden
404 Not Found
500 Internal Server Error
501 Not Implemented
503 Service Unavailable
There’s a lot to be said for graceful error handling, especially when it comes to publicly accessible
web sites. Flask lets you easily custom handle errors as well as throw them when needed.

11. FLASK: TEMPLATES
Templating keeps the logic of your web app separate from its layout and style. Ideally, we want to avoid
scenarios where we are processing any HTML within our main Python syntax.
VS

12. FLASK: TEMPLATES
Templating is handled by Jinja2, a python-esque framework that allows for control statements and loops to
be placed into HTML templates, but discourages full logic processing within HTML blocks.
In our current example, we are
passing 3 variables through
“render_template” on the Python
side: article_title, user, & posts.
If article_title is provided we prepend
it in the document header.
We also have a for loop that goes
through an array of posts, printing out
relevant information on each
iteration.

13. FLASK: TEMPLATES
We can use Jinja2's template inheritance feature, which allows us to move the parts of the page layout that
are common to all templates and put them in a base template from which all other templates are derived.
In this example we’ve split out the display of the
posts from the standardized outline of the page.
This makes it so that we won’t have to maintain
elements like the main menu across multiple files.

14. INTERACTIVE COMPONENTS
❖ FORMS, REQUESTS, & AJAX
❖ DATABASE INTEGRATION (SQLITE)
❖ LOGGING IN / SESSIONS
❖ EMAIL SUPPORT
❖ DEPLOYMENT

15. FORMS, REQUESTS, & AJAX
Let’s use the free drag-and-
drop library dropzone.js to
demo what processing a file
upload server-side would
look like.

16. BASIC DATABASE SETUP (SQLITE)
Let’s setup a super-basic plain-text
user database that we can then
integrate into a login form.
Usually we would integrate this with
the “flask_login” package, but for the
sake of simplicity we’re going about it
at a different approach.

17. SESSIONS / LOGGING IN

18. SESSIONS / LOGGING IN
This time around we throw
sqlite into the mix to check and
see if the user exists in the
database before setting the
session ‘logged_in’ variable.

19. EMAIL SUPPORT
To use flask-mail we need to import it
in our init and configure it with the
settings we seek.
Once we’re up and running there we
can call upon that functionality from
anywhere else in the application.

20. Thank You
We really appreciate you taking the time to join in on this Flask
workshop today! If you have any questions down the line, feel
free to contact me at neil@combomash.com
Over at ComboMash Entertainment, we’re launching a kickstarter
for a game where tiy ommand a crew of oil rigger mercenaries
tasked with acquiring rare resources from uncharted planets.
Build offensive towers to attack hordes of aliens in an ever
changing environment.
If you’d like follow along with our progress, join our mailing list at
http://www.hextraction.com
Our Kickstarter campaign will be launching on April 21st and we’d
love to have your support!
Many Thanks,
Neil Grey
neil@combomash.com