Python JSON 序列化一个 Decimal 对象 [英] Python JSON serialize a Decimal object
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问题描述
我有一个 Decimal('3.9')
作为对象的一部分,并希望将其编码为一个 JSON 字符串,它应该看起来像 {'x': 3.9}代码>.我不在乎客户端的精度,所以浮点数就可以了.
I have a Decimal('3.9')
as part of an object, and wish to encode this to a JSON string which should look like {'x': 3.9}
. I don't care about precision on the client side, so a float is fine.
有没有好的方法来序列化这个?JSONDecoder 不接受 Decimal 对象,并且预先转换为浮点数会产生 {'x': 3.8999999999999999}
,这是错误的,并且会浪费带宽.
Is there a good way to serialize this? JSONDecoder doesn't accept Decimal objects, and converting to a float beforehand yields {'x': 3.8999999999999999}
which is wrong, and will be a big waste of bandwidth.
推荐答案
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)
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