Flask

Introduction

We provide Flask middleware which when coupled with:

allow us to retrieve the controller and route correlated with your source code in your web app.

Using it

Having successfully installed sqlcommenter-python’s sqlcommenter

from sqlcommenter import FlaskMiddleware

# Then in your flask programs just pass in the app
FlaskMiddleware(app)

Expected fields

This Flask integration when coupled with compatible drivers will place the following fields

Field Included by default Description Turn if off by
controller
The function being used to service an HTTP request with_controller=False
framework
“flask: with_framework=False
route
The pattern used to match an HTTP request with_route=False

End to end examples

With psycopg2

#!/usr/bin/env python3

import psycopg2
import json
import flask
app = flask.Flask(__name__)

from google.cloud.sqlcommenter import FlaskMiddleware
from google.cloud.sqlcommenter.psycopg2.extension import CommenterCursorFactory

conn = None

@app.route('/polls')
def get_polls():
    cursor = conn.cursor()
    cursor.execute("SELECT * FROM polls_question")
    str_polls = list(map(lambda s: str(s), cursor))

    cursor.close()
    return json.dumps(str_polls)

def main():
    global conn

    try:
        conn = psycopg2.connect(user='', password='$postgres$',
                host='127.0.0.1', port='5432', database='quickstart_py',
                cursor_factory=CommenterCursorFactory())

        # Now enable the middleware.
        FlaskMiddleware(app)

        # Finally run the Flask web app.
        app.run(host='localhost', port=8088, threaded=True)
    except Exception as e:
        print('Encountered exception %s'%(e))

    finally:
        if conn:
            conn.close()


if __name__ == '__main__':
    main()

which when run by python3 main.py and on visiting http://localhost:8088/polls we can see on our database logs

2019-06-08 12:19:11.284 PDT [70984] LOG:  statement: SELECT * FROM polls_question
/*controller='get_polls',db_driver='psycopg2',framework='sqlalchemy%3A1.3.4',
route='/polls',traceparent='00-5b3df77064f35f091e89fb40022e2a1d-9bbd4868cf0ba2c3-01'*/

With sqlalchemy

Having successfully installed google-cloud-sqlcommenter you can now just run

#!/usr/bin/env python3

import json
import flask
app = flask.Flask(__name__)

from sqlalchemy import create_engine, event
from sqlcommenter import FlaskMiddleware
from sqlcommenter.sqlalchemy.executor import BeforeExecuteFactory

engine = None

@app.route('/polls')
def get_polls():
    result_proxy = engine.execute("SELECT * FROM polls_question")
    str_polls = list(map(lambda s: str(s), result_proxy))

    result_proxy.close()
    return json.dumps(str_polls)

def main():
    global engine
    engine = create_engine("postgresql://:$postgres$@127.0.0.1:5432/quickstart_py")
    event.listen(engine, 'before_cursor_execute', BeforeExecuteFactory(), retval=True)

    FlaskMiddleware(app)
    app.run(host='localhost', port=8089, threaded=True)

if __name__ == '__main__':
    main()

which when run by python3 main.py and on visiting http://localhost:8089/polls we can see on our database logs

2019-06-08 12:17:59.518 PDT [73546] LOG:  statement: SELECT * FROM polls_question
/*controller='get_polls',db_driver='psycopg2%3A2.8.2%20%28dt%20dec%20pq3%20ext%20lo64%29',
dbapi_level='2.0',dbapi_threadsafety=2,driver_paramstyle='pyformat',
framework='flask%3A1.0.3',libpq_version=100001,route='/polls'*/

References

Resource URL
flask web framework http://flask.pocoo.org/
sqlcommenter-psycopg2+flask /python/psycopg2#with-flask
sqlcommenter-sqlalchemy+flask /python/sqlalchemy#with-flask