Question

我之前问过这个问题，它被标记为this的副本，但是接受的答案不起作用，甚至pylint也显示代码中存在错误。

我想做什么：

from decimal import Decimal
import json

thang = {
    'Items': [{'contact_id': Decimal('2'), 'street_name': 'Asdasd'}, {'contact_id': Decimal('1'), 'name': 'Lukas', 'customer_id': Decimal('1')}],
     'Count': 2}

print(json.dumps(thang))

这引发： TypeError: Object of type 'Decimal' is not JSON serializable

所以我尝试了链接的answer：

from decimal import Decimal
import json

thang = {
    'Items': [{'contact_id': Decimal('2'), 'street_name': 'Asdasd'}, {'contact_id': Decimal('1'), 'name': 'Lukas', 'customer_id': Decimal('1')}],
     'Count': 2}


class DecimalEncoder(json.JSONEncoder):
    def _iterencode(self, o, markers=None):
        if isinstance(o, 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)._iterencode(o, markers)


print(json.dumps(thang, cls=DecimalEncoder))

在这里，linter显示行return super(DecimalEncoder, self)._iterencode(o, markers)有错误，因为Super of 'DecimalEncoder' has no '_iterencode' member并且在运行时抛出 TypeError: Object of type 'Decimal' is not JSON serializable

我如何使这项工作？

Answer 1

那个答案结果已经过时，还有另一个answer的工作解决方案：

class DecimalEncoder(json.JSONEncoder):
    def default(self, o):
        if isinstance(o, decimal.Decimal):
            return float(o)
        return super(DecimalEncoder, self).default(o)

Answer 2

我想序列化十进制为JSON，还想反序列化它回到其他地方的字典中的实际Decimal类对象。

这是适合我的示例程序（Python 3.6）：

import json
from decimal import Decimal
import decimal

class DecimalEncoder(json.JSONEncoder):
    def default(self, obj):
        if isinstance(obj, decimal.Decimal):
            return {'__Decimal__': str(obj)}
        # Let the base class default method raise the TypeError
        return json.JSONEncoder.default(self, obj)

def as_Decimal(dct):
    if '__Decimal__' in dct:
        return decimal.Decimal(dct['__Decimal__'])
    return dct


sample_dict = {
        "sample1": Decimal("100"), 
        "sample2": [ Decimal("2.0"), Decimal("2.1") ],
        "sample3": Decimal("3.1415"),
        "other": "hello!"
    }
print("1. sample_dict is:\n{0}\n".format(sample_dict))

sample_dict_encoded_as_json_string = json.dumps(sample_dict, cls=DecimalEncoder)
print("2. sample_dict_encoded_as_json_string is:\n{0}\n".format(sample_dict_encoded_as_json_string))

sample_dict_recreated = json.loads(sample_dict_encoded_as_json_string, object_hook=as_Decimal)
print("3. sample_dict_recreated is:\n{0}\n".format(sample_dict_recreated))

这是输出：

1. sample_dict is:
{'sample1': Decimal('100'), 'sample2': [Decimal('2.0'), Decimal('2.1')], 'sample3': Decimal('3.1415'), 'other': 'hello!'}

2. sample_dict_encoded_as_json_string is:
{"sample1": {"__Decimal__": "100"}, "sample2": [{"__Decimal__": "2.0"}, {"__Decimal__": "2.1"}], "sample3": {"__Decimal__": "3.1415"}, "other": "hello!"}

3. sample_dict_recreated is:
{'sample1': Decimal('100'), 'sample2': [Decimal('2.0'), Decimal('2.1')], 'sample3': Decimal('3.1415'), 'other': 'hello!'}

希望这会有所帮助！

Python 3.x无法将Decimal（）序列化为JSON

2 个答案: