[FIXED] python 2/3 compatibility issue with exception

Issue

I wrote the following code that works with python3

try:
    json.loads(text)
except json.decoder.JSONDecodeError:
    (exception handling)

However, if I use python2, when json.loads throws the exception I get:

File "mycode.py", line xxx, in function
    except json.decoder.JSONDecodeError:
AttributeError: 'module' object has no attribute 'JSONDecodeError'

And actually, https://docs.python.org/2/library/json.html doesn't mention any JSONDecodeError exception, while https://docs.python.org/3/library/json.html does.

How can I have the code running both with python 2 and 3?

Solution

In Python 2 json.loads raises ValueError:

Python 2.7.9 (default, Sep 17 2016, 20:26:04)
>>> json.loads('#$')                                                
Traceback (most recent call last):                                  
  File "<stdin>", line 1, in <module>                               
  File "/usr/lib/python2.7/json/__init__.py", line 338, in loads    
    return _default_decoder.decode(s)                               
  File "/usr/lib/python2.7/json/decoder.py", line 366, in decode    
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())               
  File "/usr/lib/python2.7/json/decoder.py", line 384, in raw_decode
    raise ValueError("No JSON object could be decoded")             
ValueError: No JSON object could be decoded

You can try to use json.decoder.JSONDecodeError. If it fails you will know that you need to catch ValueError:

try:
    json_parse_exception = json.decoder.JSONDecodeError
except AttributeError:  # Python 2
    json_parse_exception = ValueError

Then

try:
    json.loads(text)
except json_parse_exception:
    (exception handling)

Will work in either case.

Answered By - DeepSpace