Session Storage

It is often useful to store information relevant to a user of the app for the duration of that usage session. For example the user may choose to want to save a option or be remembered as logged in. This information can either be stored client side or server side and Quart provides a system to store the information client side via Secure Cookie Sessions.

Secure Cookie Sessions

Secure Cookie Sessions store the session information on the Cookie in plain text with a signature to ensure that the information is not altered by the client. They can be used in Quart so long as the secret_key is set to a secret value.

An example usage to store a users colour preference would be,

from quart import session
...


@app.route('/')
async def index():
    return await render_template(
        'index.html',
        colour=session.get('colour', 'black'),
    )

@app.route('/colour/', methods=['POST'])
async def set_colour():
    ...
    session['colour'] = colour
    return redirect(url_for('index'))

WebSockets

Sessions can be used with WebSockets with an important caveat about cookies. A cookie can only be set on a HTTP response, and an accepted WebSocket connection cannot return a HTTP response. Therefore the default implementation, being based on cookies, will lose any modifications made during an accepted WebSocket connection.