Web Development With Flask
What is Flask?
- A Python microframework for building web applications
- Simple, easy to use
- Can write APIs or process templates
- Basically, we write server-side code with Python!
What are we doing?
- This is a hackathon!
- Our goal is to achieve a starting point for an application
- After this workshop, you will have
- A basic understanding of Flask
- A running Flask application that can be extended
- Understanding of how to seek help with Flask
Requirements
- Basic Python knowledge
- No fear of running instructions on the command line
- Sublime Text or another text editor
- The desire to learn
A Basic Flask app
from flask import Flask
app = Flask("My Application")
@app.route("/")
def hello():
return "Hello World!"
if __name__ == "__main__":
app.run()simple.py
Running our app
# Set app in Windows
$ set FLASK_APP=simple.py
# Set app in MacOSX/Linux
$ export FLASK_APP=simple.py
# Run (both)
$ flask runcommand line
result
Running our app
In Chrome
A More Complex Flask app
from flask import Flask
app = Flask("My Application")
@app.route("/user/<username>")
def hello(username):
return "This is " + username + "'s page."
if __name__ == "__main__":
app.run()less_simple.py
Rendering Templates
from flask import Flask, render_template
app = Flask("My Template Application")
@app.route("/user/<username>")
def hello(username):
return render_template('hello.html', username=username)
if __name__ == "__main__":
app.run()templates/hello.html
<!DOCTYPE html>
<html>
<head>
<title>Hello {{username}}</title>
</head>
<body>
<h1>Hello {{username}}</h1>
</body>
</html>template_example.py
Reaching an API
from flask import Flask, render_template
import urllib2, json
app = Flask("My API Application")
API_ROOT = "http://api.icndb.com/"
@app.route("/norris/<category>")
def norris(category):
url = API_ROOT + "jokes/random?limitTo=[" + category + "]"
req = urllib2.urlopen(url)
answer = json.loads(req.read())
return render_template("api_info.html", **answer)
if __name__ == "__main__":
app.run()templates/api_info.html
<!DOCTYPE html>
<html>
<head>
<title>API Data</title>
</head>
<body>
<h5>Joke search: {{type}}</h5>
<p>{{value.joke}}</p>
<small>Categories: {{",".join(value.categories)}}
</body>
</html>api_example.py
Limitations
- Flask is a microframework, so it is best for small apps
- We currently don't have users, authentication
- Database support is possible, but not simple
Next Steps
- You now have a few working examples
- Work with these examples to build a more complex app
- Need inspiration? Find a public API:
- https://github.com/toddmotto/public-apis
- Use the Flask documentation!
- http://flask.pocoo.org/docs/
Get Hacking!
- This presentation is available on GitHub
- https://github.com/jamiecounsell/flask-demo
Web Development With Flask
By Jamie Counsell
