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Why is my JSON data with null not returning 0 causing an exception?

I have an API which returns null when there are no results, else it’s usually got a count with an int. In this minimal example with a similar data structure, if either value is null I’d hope to return 0.

I thought that adding {} usually allows traversing deeper into the data I get the following:

Traceback (most recent call last): File
"/home/Documents/projects/data-reviews/test_code.py", line 52, in

total_reviews = data.get(‘data’, {}).get(‘node’, {}).get(‘reviews’, {}).get(‘aggregates’, {}).get(‘count’, {})
AttributeError: ‘NoneType’ object has no attribute ‘get’

I’m not what to do here or it try: except: the only option?

import json

resp = """{
    "data": {
        "node": {
            "myReviews": {
                "totalReviews": 0
            },
            "allReviews": {
                "aggregates": null
            }
        }
    }
}"""

data = json.loads(resp)

total_ratings = data.get('data', {}).get('node', {}).get('myReviews', {}).get('totalReviews', 0)
total_reviews = data.get('data', {}).get('node', {}).get('allReviews', {}).get('aggregates', {}).get('count', 0)
Tags:

2

Answers


  1. 0

    The fallback argument of the get method only gets used if the value is not defined. If get explicitly returns None then that is the result.

    Like you write, the common workaround is to use try/except:

    try:
    total_ratings = data['data']['node']['myReviews']['totalReviews']
except KeyError:
    total_ratings = 0
try:
    total_reviews = data['data']['node']['allReviews']['aggregates']['count']
except KeyError:
    total_reviews = 0
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  2. 0

    You can use the optional object_hook function to replace the null value.

    import json


def as_null(resp):
    if "aggregates" in resp and resp["aggregates"] is None:
        print(resp)
        resp["aggregates"] = {'count': 0}
        print(resp)
    return resp


resp = """{
    "data": {
        "node": {
            "myReviews": {
                "totalReviews": 0
                
                
            },
            "allReviews": {
                "aggregates": null
            }
        }
    }
}"""

data = json.loads(resp, object_hook=as_null)
total_ratings = data.get('data', {}).get('node', {}).get('myReviews', {}).get('aggregates', {}).get('count', 0)
total_reviews = data.get('data', {}).get('node', {}).get('allReviews', {}).get('aggregates', {}).get('count', 0)
print(data)
print(total_ratings, total_ratings)

----------------------

{'aggregates': None}
{'aggregates': {'count': 0}}
{'data': {'node': {'myReviews': {'totalReviews': 0}, 'allReviews': {'aggregates': {'count': 0}}}}}
0 0

    Or use it to immediately get the count values you need.

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