Handle JSON Decode Error when nothing returned

Question

I am parsing json data  I don t have an issue with parsing and I am using simplejson module  But some api requests returns empty value  Here is my example       all           count    0       questions                      This is the segment of my code where I parse the json object     qByUser   byUsrUrlObj read    qUserData   json loads qByUser  decode  utf-8    questionSubjs   qUserData  all    questions     As I mentioned for some requests I get the following error   Traceback  most recent call last     File  YahooQueryData py   line 164  in  lt module gt      qUserData   json loads qByUser    File   opt local Library Frameworks Python framework Versions 2 6 lib python2 6 site-packages simplejson   init   py   line 385  in loads     return  default decoder decode s    File   opt local Library Frameworks Python framework Versions 2 6 lib python2 6 site-packages simplejson decoder py   line 402  in decode     obj  end   self raw decode s  idx  w s  0  end      File   opt local Library Frameworks Python framework Versions 2 6 lib python2 6 site-packages simplejson decoder py   line 420  in raw decode     raise JSONDecodeError  No JSON object could be decoded   s  idx  simplejson decoder JSONDecodeError  No JSON object could be decoded  line 1 column 0  char 0    What would be the best way to handle this error

User · Accepted Answer

There is a rule in Python programming called "it is Easier to Ask for Forgiveness than for Permission" (in short: EAFP). It means that you should catch exceptions instead of checking values for validity.

Thus, try the following:

try:
    qByUser = byUsrUrlObj.read()
    qUserData = json.loads(qByUser).decode('utf-8')
    questionSubjs = qUserData["all"]["questions"]
except ValueError:  # includes simplejson.decoder.JSONDecodeError
    print 'Decoding JSON has failed'

EDIT: Since simplejson.decoder.JSONDecodeError actually inherits from ValueError (proof here), I simplified the catch statement by just using ValueError.

User · Answer

If you don t mind importing the json module  then the best way to handle it is through json JSONDecodeError  or json decoder JSONDecodeError as they are the same  as using default errors like ValueError could catch also other exceptions not necessarily connected to the json decode one  from json decoder import JSONDecodeError   try      qByUser   byUsrUrlObj read       qUserData   json loads qByUser  decode  utf-8       questionSubjs   qUserData  quot all quot    quot questions quot   except JSONDecodeError as e        do whatever you want    EDIT  Oct 2020   As  Jacob Lee noted in the comment  there could be the basic common TypeError raised when the JSON object is not a str  bytes  or bytearray  Your question is about JSONDecodeError  but still it is worth mentioning here as a note  to handle also this situation  but differentiate between different issues  the following could be used  from json decoder import JSONDecodeError   try      qByUser   byUsrUrlObj read       qUserData   json loads qByUser  decode  utf-8       questionSubjs   qUserData  quot all quot    quot questions quot   except JSONDecodeError as e        do whatever you want except TypeError as e        do whatever you want in this case

[python] Handle JSON Decode Error when nothing returned

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