这是我从我们的课程中提取出来的

class CommonJSONEncoder(json.JSONEncoder):

    """
    Common JSON Encoder
    json.dumps(myString, cls=CommonJSONEncoder)
    """

    def default(self, obj):

        if isinstance(obj, decimal.Decimal):
            return {'type{decimal}': str(obj)}

class CommonJSONDecoder(json.JSONDecoder):

    """
    Common JSON Encoder
    json.loads(myString, cls=CommonJSONEncoder)
    """

    @classmethod
    def object_hook(cls, obj):
        for key in obj:
            if isinstance(key, six.string_types):
                if 'type{decimal}' == key:
                    try:
                        return decimal.Decimal(obj[key])
                    except:
                        pass

    def __init__(self, **kwargs):
        kwargs['object_hook'] = self.object_hook
        super(CommonJSONDecoder, self).__init__(**kwargs)

通过unittest的:

def test_encode_and_decode_decimal(self):
    obj = Decimal('1.11')
    result = json.dumps(obj, cls=CommonJSONEncoder)
    self.assertTrue('type{decimal}' in result)
    new_obj = json.loads(result, cls=CommonJSONDecoder)
    self.assertEqual(new_obj, obj)

    obj = {'test': Decimal('1.11')}
    result = json.dumps(obj, cls=CommonJSONEncoder)
    self.assertTrue('type{decimal}' in result)
    new_obj = json.loads(result, cls=CommonJSONDecoder)
    self.assertEqual(new_obj, obj)

    obj = {'test': {'abc': Decimal('1.11')}}
    result = json.dumps(obj, cls=CommonJSONEncoder)
    self.assertTrue('type{decimal}' in result)
    new_obj = json.loads(result, cls=CommonJSONDecoder)
    self.assertEqual(new_obj, obj)

对于任何想要快速解决的人来说，这里是我如何从Django中的查询中删除Decimal的

total_development_cost_var = process_assumption_objects.values('total_development_cost').aggregate(sum_dev = Sum('total_development_cost', output_field=FloatField()))
total_development_cost_var = list(total_development_cost_var.values())

步骤1:使用，output_field=FloatField()在你的查询 步骤2:使用列表eg list(total_development_cost_var.values())

希望能有所帮助

3.9不能准确地在IEEE浮点数中表示，它总是以3.899999999999999999表示，例如，尝试打印repr(3.9)，你可以在这里阅读更多信息:

http://en.wikipedia.org/wiki/Floating_point http://docs.sun.com/source/806-3568/ncg_goldberg.html

所以如果你不想要float，唯一的选项你必须将它作为字符串发送，并允许自动将十进制对象转换为JSON，做这样的事情:

import decimal
from django.utils import simplejson

def json_encode_decimal(obj):
    if isinstance(obj, decimal.Decimal):
        return str(obj)
    raise TypeError(repr(obj) + " is not JSON serializable")

d = decimal.Decimal('3.5')
print simplejson.dumps([d], default=json_encode_decimal)

子类化json.JSONEncoder怎么样?

class DecimalEncoder(json.JSONEncoder):
    def default(self, o):
        if isinstance(o, decimal.Decimal):
            # wanted a simple yield str(o) in the next line,
            # but that would mean a yield on the line with super(...),
            # which wouldn't work (see my comment below), so...
            return (str(o) for o in [o])
        return super(DecimalEncoder, self).default(o)

然后像这样使用它:

json.dumps({'x': decimal.Decimal('5.5')}, cls=DecimalEncoder)

Simplejson 2.1及更高版本原生支持十进制类型:

>>> json.dumps(Decimal('3.9'), use_decimal=True)
'3.9'

注意，use_decimal默认为True:

def dumps(obj, skipkeys=False, ensure_ascii=True, check_circular=True,
    allow_nan=True, cls=None, indent=None, separators=None,
    encoding='utf-8', default=None, use_decimal=True,
    namedtuple_as_object=True, tuple_as_array=True,
    bigint_as_string=False, sort_keys=False, item_sort_key=None,
    for_json=False, ignore_nan=False, **kw):

So:

>>> json.dumps(Decimal('3.9'))
'3.9'

希望该特性将包含在标准库中。

基于stdOrgnlDave的答案，我已经定义了这个包装器，它可以被可选的类型调用，所以编码器将只适用于项目中的某些类型。我相信工作应该在你的代码中完成，而不是使用这个“默认”编码器，因为“显式比隐式更好”，但我知道使用这将节省你的一些时间。: -)

import time
import json
import decimal
from uuid import UUID
from datetime import datetime

def JSONEncoder_newdefault(kind=['uuid', 'datetime', 'time', 'decimal']):
    '''
    JSON Encoder newdfeault is a wrapper capable of encoding several kinds
    Use it anywhere on your code to make the full system to work with this defaults:
        JSONEncoder_newdefault()  # for everything
        JSONEncoder_newdefault(['decimal'])  # only for Decimal
    '''
    JSONEncoder_olddefault = json.JSONEncoder.default

    def JSONEncoder_wrapped(self, o):
        '''
        json.JSONEncoder.default = JSONEncoder_newdefault
        '''
        if ('uuid' in kind) and isinstance(o, uuid.UUID):
            return str(o)
        if ('datetime' in kind) and isinstance(o, datetime):
            return str(o)
        if ('time' in kind) and isinstance(o, time.struct_time):
            return datetime.fromtimestamp(time.mktime(o))
        if ('decimal' in kind) and isinstance(o, decimal.Decimal):
            return str(o)
        return JSONEncoder_olddefault(self, o)
    json.JSONEncoder.default = JSONEncoder_wrapped

# Example
if __name__ == '__main__':
    JSONEncoder_newdefault()