Correct way to try except using Python requests module

Question

try      r   requests get url  params   s   thing   except requests ConnectionError  e      print e  should I also sys exit 1  after this    Is this correct  Is there a better way to structure this  Will this cover all my bases

User · Answer

Exception object also contains original response e response  that could be useful if need to see error body in response from the server  For example   try      r   requests post  somerestapi com post-here   data   birthday    9 9 3999        r raise for status   except requests exceptions HTTPError as e      print  e response text

User · Answer

One additional suggestion to be explicit  It seems best to go from specific to general down the stack of errors to get the desired error to be caught  so the specific ones don t get masked by the general one   url  http   www google com blahblah   try      r   requests get url timeout 3      r raise for status   except requests exceptions HTTPError as errh      print   Http Error   errh  except requests exceptions ConnectionError as errc      print   Error Connecting   errc  except requests exceptions Timeout as errt      print   Timeout Error   errt  except requests exceptions RequestException as err      print   OOps  Something Else  err   Http Error  404 Client Error  Not Found for url  http   www google com blahblah   vs  url  http   www google com blahblah   try      r   requests get url timeout 3      r raise for status   except requests exceptions RequestException as err      print   OOps  Something Else  err  except requests exceptions HTTPError as errh      print   Http Error   errh  except requests exceptions ConnectionError as errc      print   Error Connecting   errc  except requests exceptions Timeout as errt      print   Timeout Error   errt        OOps  Something Else 404 Client Error  Not Found for url  http   www google com blahblah

User · Answer

Have a look at the Requests exception docs   In short   In the event of a network problem  e g  DNS failure  refused connection  etc   Requests will raise a ConnectionError exception  In the event of the rare invalid HTTP response  Requests will raise an HTTPError exception  If a request times out  a Timeout exception is raised  If a request exceeds the configured number of maximum redirections  a TooManyRedirects exception is raised  All exceptions that Requests explicitly raises inherit from requests exceptions RequestException   To answer your question  what you show will not cover all of your bases  You ll only catch connection-related errors  not ones that time out  What to do when you catch the exception is really up to the design of your script program  Is it acceptable to exit  Can you go on and try again   If the error is catastrophic and you can t go on  then yes  you may abort your program by raising SystemExit  a nice way to both print an error and call sys exit   You can either catch the base-class exception  which will handle all cases  try      r   requests get url  params   s   thing   except requests exceptions RequestException as e     This is the correct syntax     raise SystemExit e   Or you can catch them separately and do different things  try      r   requests get url  params   s   thing   except requests exceptions Timeout        Maybe set up for a retry  or continue in a retry loop except requests exceptions TooManyRedirects        Tell the user their URL was bad and try a different one except requests exceptions RequestException as e        catastrophic error  bail      raise SystemExit e    As Christian pointed out   If you want http errors  e g  401 Unauthorized  to raise exceptions  you can call Response raise for status  That will raise an HTTPError  if the response was an http error   An example  try      r   requests get  http   www google com nothere       r raise for status   except requests exceptions HTTPError as err      raise SystemExit err   Will print  404 Client Error  Not Found for url  http   www google com nothere

[python] Correct way to try/except using Python requests module?

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