parse empty string using json

Question

I was wondering if there was a way to use json.loads in order to automatically convert an empty string in something else, such as None.

For example, given:

data = json.loads('{"foo":"5", "bar":""}')

I would like to have:

data = {"foo":"5", "bar":None}

Instead of:

data = {"foo":"5", "bar":""}

Answer 1

You can use a dictionary comprehension:

data = json.loads('{"foo":"5", "bar":""}')
res = {k: v if v != '' else None for k, v in data.items()}

{'foo': '5', 'bar': None}

This will only deal with the first level of a nested dictionary. You can use a recursive function to deal with the more generalised nested dictionary case:

def updater(d, inval, outval):
    for k, v in d.items():
        if isinstance(v, dict):
            updater(d[k], inval, outval)
        else:
            if v == '':
                d[k] = None
    return d

data = json.loads('{"foo":"5", "bar":"", "nested": {"test": "", "test2": "5"}}')

res = updater(data, '', None)

{'foo': '5', 'bar': None,
 'nested': {'test': None, 'test2': '5'}}