Check if request.json() is NoneType

Question

I am making API Calls and expect to get some null responses or NoneTypes. However I am trying to handle them gracefully.

This is the default behavior:

res = req.json()
res.get("key", {}).get("key") 
AttributeError: 'NoneType' object has no attribute 'get'

Below are the ways I've tried to catch it, but didn't work:

if res is None or isinstance(res, type(None)) or len(res) == 0

The NoneType errors in question have len(req.text) = 16 ?
Vs +1k for the not NoneType errors.

Currently catching them this way:

if len(req.text) < 100: # Empty JSON Object
 return None

But I am pretty sure this isn't the best practice.
Can someone help resolve this issue ?

UPDATE

print(type(res))
<class 'dict'>
print(res)
{'key': None}

SOLUTION

if res.get("key") is None:
 return None

Should have inspected further.

MEA CULPA

I am realizing that the AttributeError was about the second .get("key") and not the former .get("key", {}) while I didn't include it (the 2nd get) in my original, unedited, post.

The type of res.get("key", {}) is None

Sorry & Thanks to all !

Answer 1

Can you explain how the middle options don't work? If res is None, I'd think either of the first two clauses of your or expression should catch it. If it's something other than None, I'd expect you to get a different exception. What is the contents of req.text when you say it's length 16?

Answer 2

Just if response is None:, or if response is not None: to ensure that is isn't None. You show something similar to that and say that it didn't work, but it will.

Answer 3

Can't explain but I kept getting the AttributeError. The middle conditional statement would not catch it.

Maybe because JSON is a complex object ?

The length 16 might be the usual header and an empty body. I didn't check the text. Only the length.

Answer 4

because it is possible that response is a list or number or even an string.
in that scenario is is not null but also you can't call that with a get. you can first check it is a json or not.

isinstance(res, dict)

Answer 5

Print out response before attempting to use it and see what it is. It likely has a different structure than what you expect.

Also, if you get an error, post the full error and not just a small fraction of it like AttributeError.

Answer 6

It should returns a Dict. I get the item of the JSON object using get('key', {}).

You're right. I'll inspect what is the type / response of the JSON when I get AttributeError.

The AttributeError is the full error.

Thanks.

Answer 7

You might still be getting an AttributeError, but if you screen out the None values, it should say something other than 'NoneType' object has no attribute 'get'. What it does say should give you a hint at what the actual object is in that case. There must be two different failure modes, and you're only screening for one of them.

Answer 8

It's very likely that the HTTP response code is not 200. Did you check that? Either way, the response text doesn't represent valid JSON