Python 带有simplejson后端的jsonpickle将十进制序列化为null
我试图在Python3.7中使用jsonpickle将对象树序列化为json。但是,所有的Python 带有simplejson后端的jsonpickle将十进制序列化为null,python,python-3.x,simplejson,jsonpickle,Python,Python 3.x,Simplejson,Jsonpickle,我试图在Python3.7中使用jsonpickle将对象树序列化为json。但是,所有的Decimals都被序列化为null。我使用simplejson作为后端,因此应该能够序列化小数 如何将(复杂的)对象树序列化为json,包括小数 示例代码(需要安装simplejson和jsonpickle): 预期的序列化json应该是{“amount”:1.0},由于舍入错误,我不想使用float import jsonpickle from decimal import Decimal jsonp
Decimal
s都被序列化为null
。我使用simplejson作为后端,因此应该能够序列化小数
如何将(复杂的)对象树序列化为json,包括小数
示例代码(需要安装simplejson和jsonpickle):
预期的序列化json应该是{“amount”:1.0}
,由于舍入错误,我不想使用float
import jsonpickle
from decimal import Decimal
jsonpickle.set_preferred_backend('simplejson')
jsonpickle.set_encoder_options('simplejson', use_decimal=True)
class MyClass():
def __init__(self, amount):
self.amount = amount
def to_json(self):
return jsonpickle.dumps(self, unpicklable=False)
if __name__ == '__main__':
obj = MyClass(Decimal('1.0'))
print(obj.to_json()) # prints '{"amount": null}'
PS我不在乎使用jsonpickle。因此,将复杂对象树序列化为json(包括十进制字段)的jsonpickle替代方案也很受欢迎。您需要注册一个处理程序来处理十进制类
import jsonpickle
from decimal import Decimal
jsonpickle.set_preferred_backend('simplejson')
jsonpickle.set_encoder_options('simplejson', use_decimal=True)
class DecimalHandler(jsonpickle.handlers.BaseHandler):
def flatten(self, obj, data):
return obj.__str__() #Convert to json friendly format
jsonpickle.handlers.registry.register(Decimal, DecimalHandler)
class MyClass():
def __init__(self, amount):
self.amount = amount
def to_json(self):
return jsonpickle.dumps(self, unpicklable=False)
if __name__ == '__main__':
obj = MyClass(Decimal('1.0'))
print(obj.to_json())
更新答案:jsonpickle的主分支现在有一个use_decimal模式,允许您在不使用任何自定义处理程序的情况下实现此结果
import decimal
import unittest
import jsonpickle
class Example(object):
"""Example class holding a Decimal"""
def __init__(self, amount):
self.amount = decimal.Decimal(amount)
class UseDecimalTestCase(unittest.TestCase):
"""Demonstrate the new use_decimal mode"""
def test_use_decimal(self):
obj = Example(0.5)
# Configure simplejson to use decimals.
jsonpickle.set_encoder_options('simplejson', use_decimal=True, sort_keys=True)
jsonpickle.set_preferred_backend('simplejson')
as_json = jsonpickle.dumps(obj, unpicklable=False, use_decimal=True)
print(as_json)
# {"amount": 0.5}
# Configure simplejson to get back Decimal when restoring from json.
jsonpickle.set_decoder_options('simplejson', use_decimal=True)
obj_clone = jsonpickle.loads(as_json)
# NOTE: we get back a dict, not an Example instance.
self.assertTrue(isinstance(obj_clone, dict))
# But, the Decimal *is* preserved
self.assertTrue(isinstance(obj_clone['amount'], decimal.Decimal))
self.assertEqual(obj.amount, obj_clone['amount'])
# Side-effect of simplejson decimal mode:
# floats become Decimal when round-tripping
obj.amount = 0.5 # float
as_json = jsonpickle.dumps(obj, unpicklable=False)
obj_clone = jsonpickle.loads(as_json)
self.assertTrue(isinstance(obj_clone['amount'], decimal.Decimal))
if __name__ == '__main__':
unittest.main()
相关问题:
对于较旧的jsonpickle版本:
这可以通过允许simplejson进行编码的自定义传递处理程序来完成。您必须配置编码器和解码器选项,以便返回小数。如果您不关心往返,那么用例就更简单了
import decimal
import unittest
import jsonpickle
from jsonpickle.handlers import BaseHandler
class SimpleDecimalHandler(BaseHandler):
"""Simple pass-through handler so that simplejson can do the encoding"""
def flatten(self, obj, data):
return obj
def restore(self, obj):
return obj
class Example(object):
"""Example class holding a Decimal"""
def __init__(self, amount):
self.amount = decimal.Decimal(amount)
class DecimalTestCase(unittest.TestCase):
"""Test Decimal json serialization"""
def test_custom_handler(self):
obj = Example(0.5)
# Enable the simplejson Decimal handler -- slightly simpler than jsonpickle's
# default handler which does the right thing already.
# If you don't care about the json representation then you don't
# need to do anything -- jsonpickle preserves decimal by default
# when using its default dumps() options.
#
# We use this decimal handler so that simplejson does the encoding
# rather than jsonpickle. Thus, we have to configure simplejson too,
# which is not needed otherwise when using jsonpickle's defaults.
jsonpickle.set_encoder_options('simplejson', use_decimal=True, sort_keys=True)
jsonpickle.set_decoder_options('simplejson', use_decimal=True)
jsonpickle.set_preferred_backend('simplejson')
SimpleDecimalHandler.handles(decimal.Decimal)
as_json = jsonpickle.dumps(obj)
print(as_json)
# {"amount": 0.5, "py/object": "__main__.Example"}
# NOTE: this comes back as an Example instance
clone = jsonpickle.loads(as_json)
self.assertTrue(isinstance(clone, Example))
self.assertTrue(isinstance(clone.amount, decimal.Decimal))
self.assertEqual(obj.amount, clone.amount)
# We can simplify the JSON representation a little further
# by using unpickleable=False, but we lose the Example class.
as_json = jsonpickle.dumps(obj, unpicklable=False)
# Upside: this prints {"amount": 0.5}
# Downside: this object cannot be reconstructed back into an
# instance of the Example class.
print(as_json)
# NOTE: we get back a dict, not an Example instance.
obj_clone = jsonpickle.loads(as_json)
self.assertTrue(isinstance(obj_clone, dict))
# But, the Decimal *is* preserved
self.assertTrue(isinstance(obj_clone['amount'], decimal.Decimal))
self.assertEqual(obj.amount, obj_clone['amount'])
if __name__ == '__main__':
unittest.main()
这实际上打印的是
{“amount”:“1.0”}
,我希望它是{“amount”:1.0}
(小数点周围没有引号)。@JessedeWit您可以将obj.\uu str_uuuuuuuuuuuuuu()转换为带浮点数的浮点数(obj.\uu str_uuuuuuuuuuuuuuu()),我担心浮点数会产生舍入错误。这就是我尝试使用simplejson的原因。simplejson能够序列化小数,但显然不能与jsonpickle一起使用。