When to use `raise_for_status` vs `status_code` testing

Question

I have always used:

r = requests.get(url)
if r.status_code == 200:
    # my passing code
else:
    # anything else, if this even exists

Now I was working on another issue and decided to allow for other errors and am instead now using:

try:
    r = requests.get(url)
    r.raise_for_status()
except requests.exceptions.ConnectionError as err:
    # eg, no internet
    raise SystemExit(err)
except requests.exceptions.HTTPError as err:
    # eg, url, server and other errors
    raise SystemExit(err)
# the rest of my code is going here

With the exception that various other errors could be tested for at this level, is one method any better than the other?

Answer 1

Response.raise_for_status() is just a built-in method for checking status codes and does essentially the same thing as your first example.

There is no "better" here, just about personal preference with flow control. My preference is toward try/except blocks for catching errors in any call, as this informs the future programmer that these conditions are some sort of error. If/else doesn't necessarily indicate an error when scanning code.

---

Edit: Here's my quick-and-dirty pattern.

import time

import requests
from requests.exceptions import HTTPError

url = "https://theurl.com"
retries = 3

for n in range(retries):
    try:
        response = requests.get(url)
        response.raise_for_status()

        break

    except HTTPError as exc:
        code = exc.response.status_code
        
        if code in [429, 500, 502, 503, 504]:
            # retry after n seconds
            time.sleep(n)
            continue

        raise
      

However, in most scenarios, I subclass requests.Session, make a custom HTTPAdapter that handles exponential backoffs, and the above lives in an overridden requests.Session.request method. An example of that can be seen here.