295 lines
8.3 KiB
Python
295 lines
8.3 KiB
Python
|
"""
|
||
|
|
Custom handlers may be created to handle other objects. Each custom handler
|
||
|
|
must derive from :class:`jsonpickle.handlers.BaseHandler` and
|
||
|
|
implement ``flatten`` and ``restore``.
|
||
|
|
|
||
|
|
A handler can be bound to other types by calling
|
||
|
|
:func:`jsonpickle.handlers.register`.
|
||
|
|
|
||
|
|
"""
|
||
|
|
from __future__ import absolute_import, division, unicode_literals
|
||
|
|
import array
|
||
|
|
import copy
|
||
|
|
import datetime
|
||
|
|
import io
|
||
|
|
import re
|
||
|
|
import sys
|
||
|
|
import threading
|
||
|
|
import uuid
|
||
|
|
|
||
|
|
from . import compat
|
||
|
|
from . import util
|
||
|
|
|
||
|
|
|
||
|
|
class Registry(object):
|
||
|
|
def __init__(self):
|
||
|
|
self._handlers = {}
|
||
|
|
self._base_handlers = {}
|
||
|
|
|
||
|
|
def get(self, cls_or_name, default=None):
|
||
|
|
"""
|
||
|
|
:param cls_or_name: the type or its fully qualified name
|
||
|
|
:param default: default value, if a matching handler is not found
|
||
|
|
|
||
|
|
Looks up a handler by type reference or its fully
|
||
|
|
qualified name. If a direct match
|
||
|
|
is not found, the search is performed over all
|
||
|
|
handlers registered with base=True.
|
||
|
|
"""
|
||
|
|
handler = self._handlers.get(cls_or_name)
|
||
|
|
# attempt to find a base class
|
||
|
|
if handler is None and util.is_type(cls_or_name):
|
||
|
|
for cls, base_handler in self._base_handlers.items():
|
||
|
|
if issubclass(cls_or_name, cls):
|
||
|
|
return base_handler
|
||
|
|
return default if handler is None else handler
|
||
|
|
|
||
|
|
def register(self, cls, handler=None, base=False):
|
||
|
|
"""Register the a custom handler for a class
|
||
|
|
|
||
|
|
:param cls: The custom object class to handle
|
||
|
|
:param handler: The custom handler class (if
|
||
|
|
None, a decorator wrapper is returned)
|
||
|
|
:param base: Indicates whether the handler should
|
||
|
|
be registered for all subclasses
|
||
|
|
|
||
|
|
This function can be also used as a decorator
|
||
|
|
by omitting the `handler` argument::
|
||
|
|
|
||
|
|
@jsonpickle.handlers.register(Foo, base=True)
|
||
|
|
class FooHandler(jsonpickle.handlers.BaseHandler):
|
||
|
|
pass
|
||
|
|
|
||
|
|
"""
|
||
|
|
if handler is None:
|
||
|
|
|
||
|
|
def _register(handler_cls):
|
||
|
|
self.register(cls, handler=handler_cls, base=base)
|
||
|
|
return handler_cls
|
||
|
|
|
||
|
|
return _register
|
||
|
|
if not util.is_type(cls):
|
||
|
|
raise TypeError('{!r} is not a class/type'.format(cls))
|
||
|
|
# store both the name and the actual type for the ugly cases like
|
||
|
|
# _sre.SRE_Pattern that cannot be loaded back directly
|
||
|
|
self._handlers[util.importable_name(cls)] = self._handlers[cls] = handler
|
||
|
|
if base:
|
||
|
|
# only store the actual type for subclass checking
|
||
|
|
self._base_handlers[cls] = handler
|
||
|
|
|
||
|
|
def unregister(self, cls):
|
||
|
|
self._handlers.pop(cls, None)
|
||
|
|
self._handlers.pop(util.importable_name(cls), None)
|
||
|
|
self._base_handlers.pop(cls, None)
|
||
|
|
|
||
|
|
|
||
|
|
registry = Registry()
|
||
|
|
register = registry.register
|
||
|
|
unregister = registry.unregister
|
||
|
|
get = registry.get
|
||
|
|
|
||
|
|
|
||
|
|
class BaseHandler(object):
|
||
|
|
def __init__(self, context):
|
||
|
|
"""
|
||
|
|
Initialize a new handler to handle a registered type.
|
||
|
|
|
||
|
|
:Parameters:
|
||
|
|
- `context`: reference to pickler/unpickler
|
||
|
|
|
||
|
|
"""
|
||
|
|
self.context = context
|
||
|
|
|
||
|
|
def __call__(self, context):
|
||
|
|
"""This permits registering either Handler instances or classes
|
||
|
|
|
||
|
|
:Parameters:
|
||
|
|
- `context`: reference to pickler/unpickler
|
||
|
|
"""
|
||
|
|
self.context = context
|
||
|
|
return self
|
||
|
|
|
||
|
|
def flatten(self, obj, data):
|
||
|
|
"""
|
||
|
|
Flatten `obj` into a json-friendly form and write result to `data`.
|
||
|
|
|
||
|
|
:param object obj: The object to be serialized.
|
||
|
|
:param dict data: A partially filled dictionary which will contain the
|
||
|
|
json-friendly representation of `obj` once this method has
|
||
|
|
finished.
|
||
|
|
"""
|
||
|
|
raise NotImplementedError('You must implement flatten() in %s' % self.__class__)
|
||
|
|
|
||
|
|
def restore(self, obj):
|
||
|
|
"""
|
||
|
|
Restore an object of the registered type from the json-friendly
|
||
|
|
representation `obj` and return it.
|
||
|
|
"""
|
||
|
|
raise NotImplementedError('You must implement restore() in %s' % self.__class__)
|
||
|
|
|
||
|
|
@classmethod
|
||
|
|
def handles(self, cls):
|
||
|
|
"""
|
||
|
|
Register this handler for the given class. Suitable as a decorator,
|
||
|
|
e.g.::
|
||
|
|
|
||
|
|
@MyCustomHandler.handles
|
||
|
|
class MyCustomClass:
|
||
|
|
def __reduce__(self):
|
||
|
|
...
|
||
|
|
"""
|
||
|
|
registry.register(cls, self)
|
||
|
|
return cls
|
||
|
|
|
||
|
|
|
||
|
|
class ArrayHandler(BaseHandler):
|
||
|
|
"""Flatten and restore array.array objects"""
|
||
|
|
|
||
|
|
def flatten(self, obj, data):
|
||
|
|
data['typecode'] = obj.typecode
|
||
|
|
data['values'] = self.context.flatten(obj.tolist(), reset=False)
|
||
|
|
return data
|
||
|
|
|
||
|
|
def restore(self, data):
|
||
|
|
typecode = data['typecode']
|
||
|
|
values = self.context.restore(data['values'], reset=False)
|
||
|
|
if typecode == 'c':
|
||
|
|
values = [bytes(x) for x in values]
|
||
|
|
return array.array(typecode, values)
|
||
|
|
|
||
|
|
|
||
|
|
ArrayHandler.handles(array.array)
|
||
|
|
|
||
|
|
|
||
|
|
class DatetimeHandler(BaseHandler):
|
||
|
|
|
||
|
|
"""Custom handler for datetime objects
|
||
|
|
|
||
|
|
Datetime objects use __reduce__, and they generate binary strings encoding
|
||
|
|
the payload. This handler encodes that payload to reconstruct the
|
||
|
|
object.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def flatten(self, obj, data):
|
||
|
|
pickler = self.context
|
||
|
|
if not pickler.unpicklable:
|
||
|
|
if hasattr(obj, 'isoformat'):
|
||
|
|
result = obj.isoformat()
|
||
|
|
else:
|
||
|
|
result = compat.ustr(obj)
|
||
|
|
return result
|
||
|
|
cls, args = obj.__reduce__()
|
||
|
|
flatten = pickler.flatten
|
||
|
|
payload = util.b64encode(args[0])
|
||
|
|
args = [payload] + [flatten(i, reset=False) for i in args[1:]]
|
||
|
|
data['__reduce__'] = (flatten(cls, reset=False), args)
|
||
|
|
return data
|
||
|
|
|
||
|
|
def restore(self, data):
|
||
|
|
cls, args = data['__reduce__']
|
||
|
|
unpickler = self.context
|
||
|
|
restore = unpickler.restore
|
||
|
|
cls = restore(cls, reset=False)
|
||
|
|
value = util.b64decode(args[0])
|
||
|
|
params = (value,) + tuple([restore(i, reset=False) for i in args[1:]])
|
||
|
|
return cls.__new__(cls, *params)
|
||
|
|
|
||
|
|
|
||
|
|
DatetimeHandler.handles(datetime.datetime)
|
||
|
|
DatetimeHandler.handles(datetime.date)
|
||
|
|
DatetimeHandler.handles(datetime.time)
|
||
|
|
|
||
|
|
|
||
|
|
class RegexHandler(BaseHandler):
|
||
|
|
"""Flatten _sre.SRE_Pattern (compiled regex) objects"""
|
||
|
|
|
||
|
|
def flatten(self, obj, data):
|
||
|
|
data['pattern'] = obj.pattern
|
||
|
|
return data
|
||
|
|
|
||
|
|
def restore(self, data):
|
||
|
|
return re.compile(data['pattern'])
|
||
|
|
|
||
|
|
|
||
|
|
RegexHandler.handles(type(re.compile('')))
|
||
|
|
|
||
|
|
|
||
|
|
class QueueHandler(BaseHandler):
|
||
|
|
"""Opaquely serializes Queue objects
|
||
|
|
|
||
|
|
Queues contains mutex and condition variables which cannot be serialized.
|
||
|
|
Construct a new Queue instance when restoring.
|
||
|
|
|
||
|
|
"""
|
||
|
|
|
||
|
|
def flatten(self, obj, data):
|
||
|
|
return data
|
||
|
|
|
||
|
|
def restore(self, data):
|
||
|
|
return compat.queue.Queue()
|
||
|
|
|
||
|
|
|
||
|
|
QueueHandler.handles(compat.queue.Queue)
|
||
|
|
|
||
|
|
|
||
|
|
class CloneFactory(object):
|
||
|
|
"""Serialization proxy for collections.defaultdict's default_factory"""
|
||
|
|
|
||
|
|
def __init__(self, exemplar):
|
||
|
|
self.exemplar = exemplar
|
||
|
|
|
||
|
|
def __call__(self, clone=copy.copy):
|
||
|
|
"""Create new instances by making copies of the provided exemplar"""
|
||
|
|
return clone(self.exemplar)
|
||
|
|
|
||
|
|
def __repr__(self):
|
||
|
|
return '<CloneFactory object at 0x{:x} ({})>'.format(id(self), self.exemplar)
|
||
|
|
|
||
|
|
|
||
|
|
class UUIDHandler(BaseHandler):
|
||
|
|
"""Serialize uuid.UUID objects"""
|
||
|
|
|
||
|
|
def flatten(self, obj, data):
|
||
|
|
data['hex'] = obj.hex
|
||
|
|
return data
|
||
|
|
|
||
|
|
def restore(self, data):
|
||
|
|
return uuid.UUID(data['hex'])
|
||
|
|
|
||
|
|
|
||
|
|
UUIDHandler.handles(uuid.UUID)
|
||
|
|
|
||
|
|
|
||
|
|
class LockHandler(BaseHandler):
|
||
|
|
"""Serialize threading.Lock objects"""
|
||
|
|
|
||
|
|
def flatten(self, obj, data):
|
||
|
|
data['locked'] = obj.locked()
|
||
|
|
return data
|
||
|
|
|
||
|
|
def restore(self, data):
|
||
|
|
lock = threading.Lock()
|
||
|
|
if data.get('locked', False):
|
||
|
|
lock.acquire()
|
||
|
|
return lock
|
||
|
|
|
||
|
|
|
||
|
|
_lock = threading.Lock()
|
||
|
|
LockHandler.handles(_lock.__class__)
|
||
|
|
|
||
|
|
|
||
|
|
class TextIOHandler(BaseHandler):
|
||
|
|
"""Serialize file descriptors as None because we cannot roundtrip"""
|
||
|
|
|
||
|
|
def flatten(self, obj, data):
|
||
|
|
return None
|
||
|
|
|
||
|
|
def restore(self, data):
|
||
|
|
"""Restore should never get called because flatten() returns None"""
|
||
|
|
raise AssertionError('Restoring IO.TextIOHandler is not supported')
|
||
|
|
|
||
|
|
|
||
|
|
if sys.version_info >= (3, 8):
|
||
|
|
TextIOHandler.handles(io.TextIOWrapper)
|