Updating the webpage using Flask based on MySQL database.

Question

I have a webpage (built using HTML & jQuery) which displays the data from a MySQL database. I am using Flask to connect HTML with my database. However, my database gets updated every 15 minutes (using a separate Python Script). Currently, I stop the flask server, update the database and restart the Flask to update the webpage. My question is the following:

Is there a way to update the MySQL database in the background without having to stop the flask server? I read about concepts of AJAX and CRON, however i am not able to understand how to use them with flask asynchronously.

Note: I am a newbie in web applications and this is my first project which involves connecting client side and server side. Any help will be appreciated.

Thanks

What happens if you don't stop the Flask server, what error do you get? — Doobeh, Feb 14 '13 at 13:55
You say your database is updated every 15 minutes, then ask is there a wa to update the MySQL database in the background. As far as I can tell, that is what you're already doing with that separate python script. I really don't understand what you're asking here. — Mark Hildreth, Feb 22 '13 at 04:14

score 11 · Accepted Answer · answered Feb 15 '13 at 02:34

You are most likely doing something like this:

from flask import Flask, render_template
from yourMySqlLibrary import connect_to_mysql

conn = connect_to_mysql()
# This is only executed when you start the script
data = conn.execute("SELECT * FROM MySemiRegularlyUpdatedTable")

app = Flask(__name__)

@app.route("/")
def view_data():
    return render_template("view_data.html", data=data)

if __name__ == "__main__":
    app.run()

If that is the case, then your solution is simply to move your connection and query calls into your controller so that the database is re-queried every time you hit the page:

@app.route("/")
def view_data():
    # Removed from above and placed here
    # The connection is made to the database for each request
    conn = connect_to_mysql()
    # This is only executed on every request
    data = conn.execute("SELECT * FROM MySemiRegularlyUpdatedTable")
    return render_template("view_data.html", data=data)

This way, your view will update when your data does - and you won't have to restart the server just to pick up changes to your data.

Yes, this is exactly what i was looking for. I was not connecting to my database from inside the controller. Thanks a lot :) — Prakhar Mehrotra, Feb 22 '13 at 19:32
Could you please answer this question using jquery Ajax and a refresh interval of ??? 5 minutes. TIA. I think so the view updates from the browser..... — Merlin, Feb 26 '13 at 03:47
Somewhat off-topic, but at what scope the objects initiated outside the controller live? Initialized only the first time the app is launched? Persisting across requests? — Passiday, Mar 05 '14 at 14:29

Updating the webpage using Flask based on MySQL database.

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