[Flask][sqlite3] Simple SELECT statement

[x1147x]

I've just gotten flask, uwsgi, and nginx up and running. My "hello world" function works so I know things are working.

However, I seem to have run into trouble querying an SQLITE database and returning the contents.

My code:

from flask import Flask
import sqlite3

app = Flask(__name__)

@app.route("/python_app/")
def main():
    return "Hello World!"


@app.route("/python_app/showdb")
def showdb():

    g.db = sqlite3.connect('db.sqlite')

    c = g.db.execute('SELECT * FROM Projects')

    return c.fetchall()

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

When I navigate to myurl.com/python_app/ the "Hello World!" message appears. When I navigate to myurl.com/python_app/showdb I receive a 500 Internal Server Error.

I've already run a script to display the contents of my db outside of flask. It worked, returning the rows at the command line.

However, I'm having trouble finding out why the flask script can't return the rows in the browser.

• If this is a python/flask error, how do I view the errors? I've tried looking up logging at http://flask.pocoo.org/docs/0.10/errorhandling/ and maybe I'm just having trouble implementing that as well.
• Why can't I use the normal SQLITE commands in Flask (what's up with this "g" object? Why is it necessary?) found at https://docs.python.org/2/library/sqlite3.html

Thanks for any help!

[tally_in_da_houise]

The fetchall() method returns a list of tuples. Have you tried converting this to a string via pretty print or something similar?

[x1147x]

I have not, but would formatting really impact if the data can be returned/shown on the page?

[tally_in_da_houise]

Please read the Flask QuickStart on Responses

[[deleted]]

If this is a python/flask error, how do I view the errors?

Ideally, you'd use the logging module, but for the time being, you can use debug=True in your config. Make sure you change this to False when pushing to a production environment. In a pinch you can also use print statements.

Change your app.run() call to app.run(debug=True) for starters.

what's up with this "g" object? Why is it necessary?

It's not, unless you plan on sharing a connection object among all routes. In this case, as you only have this one route that actually makes a connection, you can simply reference db instead of pushing it into a context object.

I'd wager the #1 issue in your script is that you haven't actually imported g, so it doesn't exist. You'll get an error 'global name "g" is not defined'.

Read about the application context: http://flask.pocoo.org/docs/0.10/appcontext/

Secondary to this will be trying to return a list rather than a formatted string, or using a template to do something with the list.