Serializer / Encoder

The serializer returns ASCII data that can safely be used in an HTML template. Apostrophes, ampersands, greater-than, and less-then signs are encoded as unicode escaped sequences. E.g. this snippet is safe for any and all input:

"<a onclick='alert(" + encode(data) + ")'>show message</a>"

Unless the input contains infinite or NaN values, the result will be valid JSON data.

Quick Encoder Summary

encode(data, *[, options]) Serializes a Python object to a JSON5 compatible unicode string.
encode_bytes(data, *[, options]) Serializes a Python object to a JSON5 compatible bytes string.
encode_callback(data, cb[, supply_bytes, …]) Serializes a Python object into a callback function.
encode_io(data, fp[, supply_bytes, options]) Serializes a Python object into a file-object.
encode_noop(data, *[, options]) Test if the input is serializable.
dump(obj, fp, **kw) Serializes a Python object to a JSON5 compatible unicode string.
dumps(obj, **kw) Serializes a Python object to a JSON5 compatible unicode string.
Options Customizations for the encoder_*(...) function family.
Json5EncoderException Base class of any exception thrown by the serializer.
Json5UnstringifiableType([message, …]) The encoder was not able to stringify the input, or it was told not to by the supplied Options.

Full Encoder Description

pyjson5.encode(data, *, options=None, **options_kw)

Serializes a Python object to a JSON5 compatible unicode string.

encode(['Hello', 'world!']) == '["Hello","world!"]'
Parameters:
  • data (object) – Python object to serialize.
  • options (Optional[Options]) – Extra options for the encoder. If options and options_kw are specified, then options.update(**options_kw) is used.
  • options_kw – See Option’s arguments.
Raises:
Returns:

Unless float('inf') or float('nan') is encountered, the result will be valid JSON data (as of RFC8259).

The result is always ASCII. All characters outside of the ASCII range are encoded.

The result safe to use in an HTML template, e.g. <a onclick='alert({{ encode(url) }})'>show message</a>. Apostrophes "'" are encoded as "\u0027", less-than, greater-than, and ampersand likewise.
Return type:

str
pyjson5.encode_bytes(data, *, options=None, **options_kw)

Serializes a Python object to a JSON5 compatible bytes string.

encode_bytes(['Hello', 'world!']) == b'["Hello","world!"]'
Parameters:
Raises:
Returns:

see encode(…)
Return type:

bytes
pyjson5.encode_callback(data, cb, supply_bytes=False, *, options=None, **options_kw)

Serializes a Python object into a callback function.

The callback function cb gets called with single characters and strings until the input data is fully serialized.

encode_callback(['Hello', 'world!'], print)
#prints:
# [
# "
# Hello
# "
# ,
# "
# world!
# "
" ]
Parameters:
  • data (object) – see encode(…)
  • cb (Callable[[Union[bytes|str]], None]) – A callback function. Depending on the truthyness of supply_bytes either bytes or str is supplied.
  • supply_bytes (bool) – Call cb(...) with a bytes argument if true, otherwise str.
  • options (Optional[Options]) – see encode(…)
  • options_kw – see encode(…)
Raises:
Returns:

The supplied argument cb.
Return type:

Callable[[Union[bytes|str]], None]
pyjson5.encode_io(data, fp, supply_bytes=True, *, options=None, **options_kw)

Serializes a Python object into a file-object.

The return value of fp.write(...) is not checked. If fp is unbuffered, then the result will be garbage!

Parameters:
  • data (object) – see encode(…)
  • fp (IOBase) – A file-like object to serialize into.
  • supply_bytes (bool) – Call fp.write(...) with a bytes argument if true, otherwise str.
  • options (Optional[Options]) – see encode(…)
  • options_kw – see encode(…)
Raises:
Returns:

The supplied argument fp.
Return type:

IOBase
pyjson5.encode_noop(data, *, options=None, **options_kw)

Test if the input is serializable.

Most likely you want to serialize data directly, and catch exceptions instead of using this function!

encode_noop({47: 11}) == True
encode_noop({47: object()}) == False
Parameters:
Returns:

True iff data is serializable.
Return type:

bool
class pyjson5.Options

Customizations for the encoder_*(...) function family.

Immutable. Use Options.update(**kw) to create a new Options instance.

Parameters:
  • tojson (str|False|None) –
    • str: A special method to call on objects to return a custom JSON encoded string. Must return ASCII data!
    • False: No such member exists. (Default.)
    • None: Use default.
  • posinfinity (str|False|None) –
    • str: String to represent positive infinity. Must be ASCII.
    • False: Throw an exception if float('+inf') is encountered.
    • None: Use default: "Infinity".
  • neginfinity (str|False|None) –
    • str: String to represent negative infinity. Must be ASCII.
    • False: Throw an exception if float('-inf') is encountered.
    • None: Use default: "-Infinity".
  • nan (str|False|None) –
    • str: String to represent not-a-number. Must be ASCII.
    • False: Throw an exception if float('NaN') is encountered.
    • None: Use default: "NaN".
  • intformat (str|False|None) –
    • str: Format string to use with int.
    • False: Throw an exception if an int is encountered.
    • None: Use default: "%d".
  • floatformat (str|False|None) –
    • str: Format string to use with float.
    • False: Throw an exception if a float is encountered.
    • None: Use default: "%.6e".
  • decimalformat (str|False|None) –
    • str: Format string to use with Decimal.
    • False: Throw an exception if a Decimal is encountered.
    • None: Use default: "%s".
  • mappingtypes (Iterable[type]|False|None) –
    • Iterable[type]: Classes the should be encoded to objects. Must be iterable over their keys, and implement __getitem__.
    • False: There are no objects. Any object will be encoded as list of key-value tuples.
    • None: Use default: [collections.abc.Mapping].
decimalformat

The creation argument decimalformat. None if False was specified.

floatformat

The creation argument floatformat. None if False was specified.

intformat

The creation argument intformat. None if False was specified.

mappingtypes

The creation argument mappingtypes. () if False was specified.

nan

The creation argument nan. None if False was specified.

neginfinity

The creation argument neginfinity. None if False was specified.

posinfinity

The creation argument posinfinity. None if False was specified.

tojson

The creation argument tojson. None if False was specified.

update(self, **kw)

Creates a new Options instance by modifying some members.

Encoder Compatibility Functions

pyjson5.dump(obj, fp, **kw)

Serializes a Python object to a JSON5 compatible unicode string.

Use encode_io(…) instead!

dump(obj, fp) == encode_io(obj, fp)
Parameters:
  • obj (object) – Python object to serialize.
  • fp (IOBase) – A file-like object to serialize into.
  • kw – Silently ignored.
pyjson5.dumps(obj, **kw)

Serializes a Python object to a JSON5 compatible unicode string.

Use encode(…) instead!

dumps(obj) == encode(obj)
Parameters:
  • obj (object) – Python object to serialize.
  • kw – Silently ignored.
Returns:

see encode(data)
Return type:

unicode

Encoder Exceptions

Inheritance diagram of pyjson5.Json5Exception, pyjson5.Json5EncoderException, pyjson5.Json5UnstringifiableType
class pyjson5.Json5EncoderException

Base class of any exception thrown by the serializer.

message

Human readable error description

with_traceback()

Exception.with_traceback(tb) – set self.__traceback__ to tb and return self.

class pyjson5.Json5UnstringifiableType(message=None, unstringifiable=None)

The encoder was not able to stringify the input, or it was told not to by the supplied Options.

message

Human readable error description

unstringifiable

The value that caused the problem.

with_traceback()

Exception.with_traceback(tb) – set self.__traceback__ to tb and return self.