simao
simao

Reputation: 15579

Exclude empty/null values from JSON serialization

I am serializing multiple nested dictionaries to JSON using Python with simplejson.

Is there any way to automatically exclude empty/null values?

For example, serialize this:

 {
     "dict1" : {
     "key1" : "value1",
     "key2" : None
     }
 }

to

 {
     "dict1" : {
     "key1" : "value1"
     }
 }

When using Jackson with Java you can use Inclusion.NON_NULL to do this. Is there a simplejson equivalent?

Upvotes: 33

Views: 56272

Answers (9)

dWMartin
dWMartin

Reputation: 1

I used the MatanRubin function and extended it so that it also filters Nan (float) and Null (string) to be able to talk with a Php API.

from math import isnan

def clean_nones(value):
    """
    Recursively remove all None values from dictionaries and lists, and returns
    the result as a new dictionary or list.
    """
    def checkNan(value):
        if isinstance(value, float) and isnan(value):
            return True if (isinstance(value, float) and isnan(value)) else False
        
    if isinstance(value, list):
        return [clean_nones(x) for x in value if (x is not None and  x != 'NULL' and not checkNan(x))]
    elif isinstance(value, dict):
        return {
            key: clean_nones(val)
            for key, val in value.items()
            if (val is not None and val != 'NULL' and not checkNan(val))
        }
    else:
        return value

cleanedJson = clean_nones(toCleanJson)

Upvotes: 0

PeterB
PeterB

Reputation: 121

This solution is correction of the one above from @eric which does not handle list type corectly.

Values in canonical JSON dictionary can be of one of following 3 types:

  • dictionary
  • list
  • value type (string, integer or floating point)

Note: Assumption is that we are dealing here with canonical JSON dictionary which can really contain only above mentioned types. If dictionary contains other types then ones mentioned above (e.g. tuples, custom classes, ...), then this solution won't work as expected.

The essential difference between this solution (below) and the original one from @eric is that list can contain elements of dictionary type from iside of which we want to drop elements with None value.

def cleandict(d):
    if isinstance(d, dict):
        return {k: cleandict(v) for k, v in d.items() if v is not None}
    elif isinstance(d, list):
        return [cleandict(v) for v in d]
    else:
        return d

Note: Please keep in mind that we must NOT remove None elements from the list since it would affect structural integrity of the list data. If some ( or all) of list elements have None value, they shall remain listed in the list structure as they were in order to preserve original structural meaning/integrity of the list.

Upvotes: 2

crazyDev
crazyDev

Reputation: 103

Could you maybe remain 'url' if it has value in one place and remove it if it none on another place?

'inline_keyboard': [
        [
            {'text': '0-0', 'url': 'someValue', 'login_url': None, 'callback_data': '0-0', 'switch_inline_query': None},
            {'text': '0-1', 'url': None, 'login_url': None, 'callback_data': '0-1', 'switch_inline_query': None}
        ],
        [
            {'text': '1-0', 'url': None, 'login_url': None, 'callback_data': '1-0', 'switch_inline_query': None},
            {'text': '1-1', 'url': None, 'login_url': None, 'callback_data': '1-1', 'switch_inline_query': None}
        ],
        [
            {'text': '2-0', 'url': None, 'login_url': None, 'callback_data': '2-0', 'switch_inline_query': None}
        ]
]

Upvotes: 0

Artem
Artem

Reputation: 161

You can try this approach. In my case (I use python 3), it works well.

def to_json(self):
    return json.dumps(self,
                      default=lambda o: dict((key, value) for key, value in o.__dict__.items() if value),
                      indent=4,
                      allow_nan=False)

Upvotes: 2

MrMahdi313
MrMahdi313

Reputation: 89

It works for me:

When dictionary has dict/list/tuple values ....

for example it is my object:

dict_obj = {
    'inline_keyboard': [
        [
            {'text': '0-0', 'url': None, 'login_url': None, 'callback_data': '0-0', 'switch_inline_query': None},
            {'text': '0-1', 'url': None, 'login_url': None, 'callback_data': '0-1', 'switch_inline_query': None}
        ],
        [
            {'text': '1-0', 'url': None, 'login_url': None, 'callback_data': '1-0', 'switch_inline_query': None},
            {'text': '1-1', 'url': None, 'login_url': None, 'callback_data': '1-1', 'switch_inline_query': None}
        ],
        [
            {'text': '2-0', 'url': None, 'login_url': None, 'callback_data': '2-0', 'switch_inline_query': None}
        ]
    ]
}

I wrote this function:

def delete_none_values(obj):
    if isinstance(obj, dict):
        for k, v in list(obj.items()):
            if v is None:
                del obj[k]
            elif isinstance(v, dict):
                delete_none_values(v)
            elif isinstance(v, (list, tuple)):
                for _ in v:
                    delete_none_values(_)
    elif isinstance(obj, (list, tuple)):
        for _ in obj:
            delete_none_values(_)
    return obj

And then when use this fuction:

from json import dumps

print(
    dumps(
        delete_none_values(dict_obj.copy()),
        indent=2
    )
)

output is:

{
  "inline_keyboard": [
    [
      {"text": "0-0", "callback_data": "0-0"},
      {"text": "0-1", "callback_data": "0-1"}
    ],
    [
      {"text": "1-0", "callback_data": "1-0"},
      {"text": "1-1", "callback_data": "1-1"}
    ],
    [
      {"text": "2-0", "callback_data": "2-0"}
    ]
  ]
}

Upvotes: 0

MatanRubin
MatanRubin

Reputation: 1085

My Python3 version of this has the benefit of not changing the input, as well as recursion into dictionaries nested in lists:

def clean_nones(value):
    """
    Recursively remove all None values from dictionaries and lists, and returns
    the result as a new dictionary or list.
    """
    if isinstance(value, list):
        return [clean_nones(x) for x in value if x is not None]
    elif isinstance(value, dict):
        return {
            key: clean_nones(val)
            for key, val in value.items()
            if val is not None
        }
    else:
        return value

For example:

a = {
    "a": None,
    "b": "notNone",
    "c": ["hello", None, "goodbye"],
    "d": [
        {
            "a": "notNone",
            "b": None,
            "c": ["hello", None, "goodbye"],
        },
        {
            "a": "notNone",
            "b": None,
            "c": ["hello", None, "goodbye"],
        }
    ]
}


print(clean_nones(a))

results in this:

{
    'b': 'notNone',
    'c': ['hello', 'goodbye'],
    'd': [
        {
            'a': 'notNone',
            'c': ['hello', 'goodbye']
        },
        {
            'a': 'notNone',
            'c': ['hello', 'goodbye']
        }
    ]
}

Upvotes: 28

Chris Morgan
Chris Morgan

Reputation: 90912

def del_none(d):
    """
    Delete keys with the value ``None`` in a dictionary, recursively.

    This alters the input so you may wish to ``copy`` the dict first.
    """
    # For Python 3, write `list(d.items())`; `d.items()` won’t work
    # For Python 2, write `d.items()`; `d.iteritems()` won’t work
    for key, value in list(d.items()):
        if value is None:
            del d[key]
        elif isinstance(value, dict):
            del_none(value)
    return d  # For convenience

Sample usage:

>>> mydict = {'dict1': {'key1': 'value1', 'key2': None}}
>>> print(del_none(mydict.copy()))
{'dict1': {'key1': 'value1'}}

Then you can feed that to json.

Upvotes: 31

eric
eric

Reputation: 355

>>> def cleandict(d):
...     if not isinstance(d, dict):
...         return d
...     return dict((k,cleandict(v)) for k,v in d.iteritems() if v is not None)
... 
>>> mydict = dict(dict1=dict(key1='value1', key2=None))
>>> print cleandict(mydict)
{'dict1': {'key1': 'value1'}}
>>> 

I don't like using del in general, changing the existing dictionary can have subtle effects depending on how they are created. Creating new dictionaries with None removed prevents all side effect.

Upvotes: 12

utapyngo
utapyngo

Reputation: 7146

def excludeNone(d):
    for k in list(d):
        if k in d:
            if type(d[k]) == dict:
                excludeNone(d[k])
            if not d[k]:
                del d[k]

Upvotes: 0

Related Questions