Custom python encoder for handling NaN, Infinity and -Infinity, which are non-valid JSON values and can possibly screw your json parser

python json FloatEncoder

import json


class FloatEncoder(json.JSONEncoder):
    def __init__(self, nan_str="null", **kwargs):
        super(FloatEncoder, self).__init__(**kwargs)
        self.nan_str = nan_str

    def iterencode(self, o, _one_shot=False):
        """Encode the given object and yield each string
        representation as available.

        For example::

            for chunk in JSONEncoder().iterencode(bigobject):
                mysocket.write(chunk)
        """
        if self.check_circular:
            markers = {}
        else:
            markers = None
        if self.ensure_ascii:
            _encoder = json.encoder.encode_basestring_ascii
        else:
            _encoder = json.encoder.encode_basestring
        if self.encoding != 'utf-8':
            def _encoder(o, _orig_encoder=_encoder, _encoding=self.encoding):
                if isinstance(o, str):
                    o = o.decode(_encoding)
                return _orig_encoder(o)

        def floatstr(o, allow_nan=self.allow_nan, _repr=json.encoder.FLOAT_REPR,
                _inf=json.encoder.INFINITY, _neginf=-json.encoder.INFINITY,
                nan_str=self.nan_str):
            # Check for specials.  Note that this type of test is processor
            # and/or platform-specific, so do tests which don't depend on the
            # internals.

            if o != o:
                text = nan_str
            elif o == _inf:
                text = 'Infinity'
            elif o == _neginf:
                text = '-Infinity'
            else:
                return _repr(o)

            if not allow_nan:
                raise ValueError(
                    "Out of range float values are not JSON compliant: " +
                    repr(o))

            return text

        _iterencode = json.encoder._make_iterencode(
                markers, self.default, _encoder, self.indent, floatstr,
                self.key_separator, self.item_separator, self.sort_keys,
                self.skipkeys, _one_shot)
        return _iterencode(o, 0)


d = {"i_will_byte_you_in_the_ass": float("NaN")}
print json.dumps(d, cls=FloatEncoder)

Thanks for this!

However, when I use this in Python 3.7, I get:

AttributeError: 'FloatEncoder' object has no attribute 'encoding'