boto3 remove Decimal() notation from dynamodb query results - python

Question

So I'm working with boto3, trying to retrieve some data from a dynamoDB table, and every number that is returned to me is using this Decimal(..) notation, like instead of getting

{
 "itemId" : 123
}
I get
{
 "itemId": Decimal(123)
}

Is there a way to remove this without having to write a regExp for it?

I was doing it manually with a for, for example using int(itemId) and it worked for some items but these are very big and complex objects that don't always have the same structure and key names, so I can't do everything like this.

Answer 1

For me, I create a DecimalEncoder class and use it to parse my data when needed. Here is an example:

import boto3
import json
import decimal

dynamodb = boto3.resource('dynamodb')
table = dynamodb.Table('MyTable')
class DecimalEncoder(json.JSONEncoder):
    """
    Helper class to convert a DynamoDB item to JSON.
    """
    def default(self, o):  # pylint: disable=E0202
        if isinstance(o, decimal.Decimal):
            if abs(o) % 1 > 0:
                return float(o)
            return int(o)
        return super(DecimalEncoder, self).default(o)


def getitem():
    ddbresponse = table.get_item(
        Key={'pk': 'a', 'sk': 'b'},
        ConsistentRead=True
    )
    return json.dumps(ddbresponse['Item'], cls=DecimalEncoder) if 'Item' in ddbresponse else ddbresponse

print(getitem())

DynamoDB has no idea what data type a number actually is, which causes python to represent it as a Decimal.