ProgrammingNotes/flask.md at main · kbroman/ProgrammingNotes

Flask

At the top of the script, need from flask import Flask

Then use app = Flask(__name__)
Set up routes with @app.route('/something') and a handler function.
```
@app.route("/')
def index():
    return 'Hello, world!'
```
HTML templates placed in templates/. Need from flask import render_template and then use render_template('index.html')
CSS files placed in static/
Use <variable> for variables in the URL. Inside a template, they'll be used as {{ variable }}. Within the python app, they're just a plain variable.
```
@app.route('/hello/<name>')
def hello(name):
    return "Hello, " + name
```
At the bottom of the script,
```
if __name__ == '__main__':
    app.run(debug=TRUE, host='0.0.0.0')
```
The host='0.0.0.0' bit makes it accessible from other computers.
As recommended by Flask Web Development book, set up virtualenv. (Seems sort of like conda; maybe the same thing.)
```
sudo apt-get install python-virtualenv

virtualenv venv -p python3
source venv/bin/activate
```
Need to install all necessary modules (e.g. pip install flask). (Flask was already installed on my raspberry pi, but was not available within the virtual environment.)

Back to normal with deactivate