Python3: unable to import JSONDecodeError from json.decoder

Question

I setup virtualenv using python 3.4.3 and tried to import JSONDecodeError from json.decoder

from json.decoder import JSONDecodeError (I think its valid in python3 ? But why not working for me ?) 

But it is not working. Only below is working:

from simplejson import JSONDecodeError

How I did ?

virtualenv venv --no-site-packages -p python3 
pip install ipython
ipython
from json.decoder import JSONDecodeError
ImportError: cannot import name 'JSONDecodeError'

Beekeeper

Is your file named json.py? Please provide full traceback. – Autopsy

from json import JSONDecodeError – Stem

Strange, this works fine for me. Can you see what happens if you try from json import decoder; print(decoder.JSONDecodeError) ? – Accipiter

In [8]: print(decoder.JSONDecodeError) --------------------------------------------------------------------------- AttributeError Traceback (most recent call last) <ipython-input-8-bb2acb16c5bc> in <module>() ----> 1 print(decoder.JSONDecodeError) AttributeError: 'module' object has no attribute 'JSONDecodeError' – Beekeeper

Attached screenshot also – Beekeeper

Answer 1

According to 3.4.x docs, plain ValueError is raised when JSON decoding fails.

JSONDecodeError class is available starting from 3.5.x.

Gwenngwenneth

Indeed. And since JSONDecodeError inherits from ValueError it is best to catch the latter if you care about portability. – Raker

Answer 2

According to Docs from module json (Python version >= 3.5.0), Python which version < 3.5.0 does not support import statement like what you just did, but if you use Python(version>=3.5.0), your import statement is definitely correct.

Leavis

Answer 3

json is the version of simplejson that has been integrated into Python. They have since been developed separately and are not the same anymore. So they cannot necessarily be used interchangably.

See this answer for more details about the differences.

Cassidy

Can you clarify whether 'from json import JSONDecodeError' is right or wrong in python3 ? – Beekeeper

As mentioned in other answers it depends on the minor version. If your questioned isn't "Why does this work with simplejson but not with json?" then I misunderstood. – Cassidy