Object of type 'Decimal' is not JSON serializable : AWS Lambda - DynamoDB

Question

Lambda execution failed with status 200 due to customer function error: Object of type 'Decimal' is not JSON serializable

I went through all the existing solutions in the following link but nothing worked for me. What am I doing wrong?: Python JSON serialize a Decimal object

import json
import boto3
import decimal


client = boto3.resource('dynamodb')
table = client.Table('table')

def lambda_handler(event, context):
    method = event["httpMethod"]
    print(event)
    if method=="POST":
        return POST(event)
    elif method=="DELETE":
        return DELETE(event)
    elif method=="GET":
        return GET(event)

#the respons format
def send_respons(responseBody, statusCode):
    response = {
        "statusCode": statusCode,
        "headers": {
            "my_header": "my_value"
        },
        "body": json.dumps(responseBody),
        "isBase64Encoded": 'false'
    }
    return response
    

def GET(event):
    tab = table.scan()['Items']
    ids = []
            for item in tab:
                    ids.append({"id":item["id"], "decimalOBJ":decimal.Decimal(item["decimalOBJ"]}))
            return send_respons(ids, 201)

Answer 1

Here is an example of extending the JSONEncoder to handle Decimal type also specified in the json docs

from decimal import Decimal

class DecimalEncoder(json.JSONEncoder):
  def default(self, obj):
    if isinstance(obj, Decimal):
      return str(obj)
    return json.JSONEncoder.default(self, obj)

Call it using

json.dumps(some_object, cls=DecimalEncoder)

By converting to a str a good degree of precision will be maintained, without relying on external packages.