Python requests exception handling

Question

How to handle exceptions with python library requests? For example how to check is PC connected to internet?

When I try

try:
    requests.get('http://www.google.com')
except ConnectionError:
    # handle the exception

it gives me error name ConnectionError is not defined

Audraaudras

Please include the traceback of the exception you're trying to handle. – Combe

Answer 1

Assuming you did import requests, you want requests.ConnectionError. ConnectionError is an exception defined by requests. See the API documentation here.

Thus the code should be:

try:
   requests.get('http://www.google.com')
except requests.ConnectionError:
   # handle the exception

---

^{The original link to the Python v2 API documentation from the original answer no longer works.}

Nolie

for clarity, that is: except requests.ConnectionError:, NOT import requests.ConnectionError – Plusch

@Plusch Thanks for the extra clarity, I was trying to import the class directly. – Vitale

It can be from requests import ConnectionError also. Wondering why is not defined in requests.exceptions submodule :-/ like urllib3 does. – Bartlett

Does not handle requests.exceptions.ReadTimeout – Seumas

Answer 2

As per the documentation, I have added the below points:

1. In the event of a network problem (refused connection e.g internet issue), Requests will raise a ConnectionError exception.

   try:
      requests.get('http://www.google.com')
   except requests.ConnectionError:
      # handle ConnectionError the exception
   

2. In the event of the rare invalid HTTP response, Requests will raise an HTTPError exception. Response.raise_for_status() will raise an HTTPError if the HTTP request returned an unsuccessful status code.

   try:
      r = requests.get('http://www.google.com/nowhere')
      r.raise_for_status()
   except requests.exceptions.HTTPError as err:
      #handle the HTTPError request here
   

3. In the event of times out of request, a Timeout exception is raised.

You can tell Requests to stop waiting for a response after a given number of seconds, with a timeout arg.

    requests.get('https://github.com/', timeout=0.001)
    # timeout is not a time limit on the entire response download; rather, 
    # an exception is raised if the server has not issued a response for
    # timeout seconds

4. All exceptions that Requests explicitly raises inherit from requests.exceptions.RequestException. So a base handler can look like,

   try:
      r = requests.get(url)
   except requests.exceptions.RequestException as e:
      # handle all the errors here
   

---

^{The original link to the Python v2 documentation no longer works, and now points to the new documentation.}

Extramural

Answer 3

Actually, there are much more exceptions that requests.get() can generate than just ConnectionError. Here are some I've seen in production:

from requests import ReadTimeout, ConnectTimeout, HTTPError, Timeout, ConnectionError

try:
    r = requests.get(url, timeout=6.0)
except (ConnectTimeout, HTTPError, ReadTimeout, Timeout, ConnectionError):
    continue

Barehanded

Note that catching Timeout will also catch both ConnectTimeout and ReadTimeout, so you can remove the latter two if you're not handling them differently. requests.readthedocs.io/en/latest/api/#requests.Timeout – Holmun

Answer 4

Include the requests module using import requests .

It is always good to implement exception handling. It does not only help to avoid unexpected exit of script but can also help to log errors and info notification. When using Python requests I prefer to catch exceptions like this:

try:
    res = requests.get(adress,timeout=30)
except requests.ConnectionError as e:
    print("OOPS!! Connection Error. Make sure you are connected to Internet. Technical Details given below.\n")
    print(str(e))            
    continue
except requests.Timeout as e:
    print("OOPS!! Timeout Error")
    print(str(e))
    continue
except requests.RequestException as e:
    print("OOPS!! General Error")
    print(str(e))
    continue
except KeyboardInterrupt:
    print("Someone closed the program")

Meagan

Don't I need a loop to use the continue statement? – Cyndie

Answer 5

for clarity, that is

except requests.ConnectionError:

NOT

import requests.ConnectionError

 

You can also catch a general exception (although this isn't recommended) with

except Exception:

Plusch