Flask 1.0: global exception handler handles not found now? #2841
Description
Hi,
We're looking at upgrading from Flask 0.12 to 1.0, and have run into an issue with routes that don't exist.
We have a custom error handler that we install for Python's built-in Exception class so that we can have a useful error message should any error occur during request execution. With Flask 1.0, we are finding that URLs that don't exist are triggering a call to the custom error handler.
We would like to preserve the behaviour so that non-existent URLs continue to return a 404/Not Found response.
I've tried reading the docs and couldn't see a way, so might have missed something:
http://flask.pocoo.org/docs/1.0/errorhandling/#error-handlers
What is the recommended way of doing this? Or is this a bug?
I wasn't 100% sure, but this could be the same as #2778?
Expected Behavior
With the Flask app running as below, the following command:
curl -XGET http://127.0.0.1:5001/does-not-exist
should return 404/Not Found.
#! python
"""
Simple Flask app with a global exception handler.
"""
from http import HTTPStatus
from flask import Flask
app = Flask(__name__)
@app.errorhandler(Exception)
def global_exception_handler(err):
""" Global exception handler.
"""
print("In global_exception_handler", err)
return "From global_exception_handler\n", HTTPStatus.INTERNAL_SERVER_ERROR
@app.route("/error")
def error():
""" Simple endpoint that raises an exception
"""
# simulate a real error that can occur during request processing
raise AttributeError("These aren't the attributes you are looking for.")
@app.route("/simple")
def simple():
""" Simple endpoint
"""
# sanity check
return "Hello World!\n", HTTPStatus.OK
def main():
""" The entry point
"""
app.run(port=5001)
if __name__ == "__main__":
main()
Actual Behavior
Our global exception handler is invoked and instead of 404/Not found we get what it returns (500/internal server error).
Command line output when running the app with Flask 1.0.2:
dan@dan-desktop:/tmp $ curl -XGET http://127.0.0.1:5001/error
From global_exception_handler
dan@dan-desktop:/tmp $ curl -XGET http://127.0.0.1:5001/does-not-exist
From global_exception_handler
dan@dan-desktop:/tmp $ curl -XGET http://127.0.0.1:5001/simple
Hello World!
Command line output when running the app with Flask 0.12.4:
dan@dan-desktop:/tmp $ curl -XGET http://127.0.0.1:5001/error
From global_exception_handler
dan@dan-desktop:/tmp $ curl -XGET http://127.0.0.1:5001/does-not-exist
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<title>404 Not Found</title>
<h1>Not Found</h1>
<p>The requested URL was not found on the server. If you entered the URL manually please check your spelling and try again.</p>
dan@dan-desktop:/tmp $ curl -XGET http://127.0.0.1:5001/simple
Hello World!
Environment
- Python version: Python 3.6.2
- Flask version: 1.0.2
- Werkzeug version: 0.14.1