Python JSON serialize a Decimal object
decimal, floating-point, json, python
Solution
How about subclassing `json.JSONEncoder`?
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)
Then use it like so:
json.dumps({'x': decimal.Decimal('5.5')}, cls=DecimalEncoder)
Problem
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. 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.