Python - Pymongo MongoDB 3.4 - NumberDecimal

问题

i am using mongodb 3.4 in order to insert proper prices to my database..

According to:

https://github.com/mongodb/specifications/blob/master/source/bson-decimal128/decimal128.rst#reading-from-extended-json

i used this in my python code:

'credits': {'$numberDecimal': Decimal128('9.99')},

but throws:

bson.errors.InvalidDocument: key '$numberDecimal' must not start with '$'

So what is the correct syntax for inserting numberdecimal in mongodb using python ?

thanks and greetings

回答1:

Simply this:

collection.insert_one({'credits': Decimal128('9.99')})

(The "$numberDecimal" syntax is for expressing a decimal number within a JSON string. But you're not using JSON at all.)

回答2:

The link you provided tells you about reading from extended JSON. If you want to insert it as a decimal, you should just use:

{ 'credits': '{0:.2f}'.format(9.99) }

The '{0:.2f}'.format(9.99) part will format the number you pass (in this case 9.99) to include 2 decimals every time. So '{0:.2f}'.format(9) should result in 9.00 in your database.

来源：https://stackoverflow.com/questions/44283527/python-pymongo-mongodb-3-4-numberdecimal