Background thread how to use socketio push real time database info to client?

This is my views file snippet:

thread = None


def background_thread(app=None):
    """
   send host status information to client
    """
    with app.app_context():
        while True:
            # update host info interval
            socketio.sleep(app.config['HOST_UPDATE_INTERVAL'])
            # socketio.sleep(5)
            all_hosts = dict([(host.id, host.status) for host in Host.query.all()])
            socketio.emit('update_host', all_hosts, namespace='/hostinfo')


@main.route('/', methods=['GET', 'POST'])
def index():
    all_hosts = Host.query.all()
    return render_template('dashboard.html', hosts=all_hosts, async_mode=socketio.async_mode)

@socketio.on('connect', namespace='/hostinfo')
def on_connect():
    global thread
    if thread is None:
        app = current_app._get_current_object()
        thread = socketio.start_background_task(target=background_thread, app=app)
    emit('my_response', {'data': 'conncted'})

@socketio.on('disconnect', namespace='/hostinfo')
def on_disconnect():
    print 'Client disconnected...', request.sid


@socketio.on('my_ping', namespace="/hostinfo")
def ping_pong():
    emit('my_pong')

I want to push real-time database Host table information to the client using a background thread which uses flask-socketio send the information. However, background thread uses current_app context, so this context is just a “snapshot”, so the database information is also just a “snapshot”, however, I want to get the real time database information just like in the app context. So how background thread use socketio push real time database info to client?

[miguelgrinberg]

@buweilv so the only problem is that you can’t get updated values from the database? Then try to clear the session, as that will eliminate all cached objects and force the next query to go to the database. Use db.session.remove().

[buweilv]

Ok , it’s not neccessary to add trouble to flask app, thanks 😃