Ayyyyyy.
Welcome to the HackGT/Tech Square Labs Python/Flask workshop. We will be building a Twitter-like web app using Python with the Flask web framework. Along the way, we will be using HTML, CSS, a lil drop of Javascript and some dark, dark magic to grease the wheels of technology and apease the programming gods.
Accompanying slides (only used to intro, the rest was live-coding) can be found here
Don't worry. It's not that crazy. [Flask] (http://flask.pocoo.org) is a simple and straightforward web framework for Python that is also extremely powerful. We will start by building a simple website that keeps track of a todo list and then move on to building the Twitter clone.
- Python 2.7 and pip
After installing Python:
On Linux or OS X:
pip install -U pipOn Windows:
python -m pip install -U pip
In hello.py:
from flask import Flask
app = Flask(__name__)
@app.route("/")
def hello():
return "Hello World!"
if __name__ == "__main__":
app.run()
Then start the web application with:
python hello.py
You can stop the program by pressing Control+C
The structure of the todo list application will remind you of the helloflask
app. The difference here is that I put the HTML/CSS/JavaScript code into a
separate folder called client. This is purely for organizational purposes
as our project grows (it won't for this example but you can see how
more complex sites could have multiple files of each type etc...).
todo/
├── client
│ ├── index.html
│ ├── main.js
│ └── style.css
└── server.py
We do have to make a small change to the code in order to serve the files from this new location.
...
def index(filepath="index.html"):
return send_from_directory("", filepath)
...
Becomes
...
def index(filepath="index.html"):
return send_from_directory("client", filepath)
...
In order to add more functionality into our web application, we need to use more of Flask's features!
Before (in the helloflask app) we only had Flask and send_from_directory
in our import statement. We will now need json and request as well.
from flask import Flask, json, send_from_directory, request
JSON is popular format for sending data across the web. XML is the other popular format. We've already seen a type of XML when we wrote our HTML. We are using JSON now because it is easier for humans to read and write and tends to be simpler to use as well.
JSON has the added benefit very closely resembling the notation that Python uses for dictionaries.
Our application is only using json in one place... can you find it?
This allows us to interact with the content of the request in Python. Open up the "Network" tab of your browser's developer tools and look at the request for creating new events.
Do you notice anything different from the GET requests we've been making?
How does the server find and use this data? Where is request being used?
- Flask documentation
- Flask tutorial
- Slides from workshop
- MiniTwit a Twitter-clone written with Flask