flask before and after request operations not working/printing anything

Question

so I have a strange error where before and after operations are not working. They previously wrote to the requests.log file, but now that is not working, AND regular print statements to the console are not working and I have no idea why:


# function to handle bson type returned by mongodb
# taken from https://stackoverflow.com/a/18405626
def parse_json(data):
    return json.loads(json_util.dumps(data))

app = flask.Flask(__name__)
api = Api(app)

#we will be logging the API end point that was accessed, the time it was accessed, and how long it took to address the request
#all logging will be to a local file, requests.log.
@app.before_request
def start_timer():
    g.start = time.time()

@app.after_request
def log_request(response):
    now = time.time()
    duration = round(now - g.start, 2)
    print(response.get_data())  #not working
    f = open("requests.log", "a+")
    f.write("testing") #also not working
    f.write("The following request took ({}) seconds".format(duration)) #not working
    f.write("\n")
    f.close()
    print("dhefei") #not working
    app.logger.info('Processing default request') #not working
    print(request.url, request.remote_addr,file=sys.stderr)
    return response

Any print statements outside of these operations do work.

score 0 · Answer 1 · answered Mar 15 '21 at 08:16

I tested your code, looks fine! But with few updates.

from flask import g, request, Flask
import logging
import time
import sys


logging.basicConfig(
    format='%(asctime)-15s %(levelname)-8s %(name)-1s: %(message)s',
    level=logging.DEBUG)

logging.getLogger("requests").setLevel(logging.WARNING)
logging.getLogger("urllib3").setLevel(logging.WARNING)

# function to handle bson type returned by mongodb
# taken from https://stackoverflow.com/a/18405626
def parse_json(data):
    return json.loads(json_util.dumps(data))

app = Flask(__name__)

@app.route('/')
def hello_world():
    time.sleep(4)
    return 'Hello, World!'

@app.before_request
def start_timer():
    g.start = time.time()

@app.after_request
def log_request(response):
    now = time.time()
    duration = round(now - g.start, 2)
    logging.info(response.get_data())  #not working
    logging.info("testing") #also not working
    logging.info("The following request took ({}) seconds".format(duration)) #not working
    logging.info("dhefei") #not working
    logging.info('Processing default request') #not working
    return response


if __name__ == '__main__':
    app.run(host='localhost', port=9999)

in console:

python3 flaskapp.py
 * Serving Flask app "flaskapp" (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: off
2021-03-15 11:13:13,723 INFO     werkzeug:  * Running on http://localhost:9999/ (Press CTRL+C to quit)
2021-03-15 11:13:19,982 INFO     root: b'Hello, World!'
2021-03-15 11:13:19,982 INFO     root: testing
2021-03-15 11:13:19,983 INFO     root: The following request took (4.0) seconds
2021-03-15 11:13:19,983 INFO     root: dhefei
2021-03-15 11:13:19,983 INFO     root: Processing default request
2021-03-15 11:13:19,985 INFO     werkzeug: 127.0.0.1 - - [15/Mar/2021 11:13:19] "GET / HTTP/1.1" 200 -

flask before and after request operations not working/printing anything

1 Answers1