Python / Boto3: Float types are not supported. Use Decimal types instead

user_1546990 0
Viewed 8474

I'm using Python 3.7 to store data in a DynamoDB database and encountering the following error message when I try and write an item to the database:

Float types are not supported. Use Decimal types instead.

My code:

ddb_table = my_client.Table(table_name)

with ddb_table.batch_writer() as batch:
    for item in items:
        item_to_put: dict = json.loads(json.dumps(item), parse_float=Decimal)

        # Send record to database.
        batch.put_item(Item=item_to_put)

"items" is a list of Python dicts. If I print out the types of the "item_to_put" dict, they are all of type str.

Thanks in advance for any assistance.

amazon-dynamodb boto3 python
3 Answers

Convert all the float to the Decimal

import json
from decimal import Decimal
item = json.loads(json.dumps(item), parse_float=Decimal)

table.put_item(
    Item=item
)
user_144113530

Ran into the same issue and it turned out that Python was passing a string parameter as something else. The issue went away when I wrapped all of the items in str().

user_58970350

Same issue here. In my case it was because some of my records did not have a certain key, and that key was being auto-added with nan by default(I guess?). I added some simple logic to check if that key was a list and set it to an empty list if not before running batch.put_item which has seemingly satisfied the Dynamo beast.

user_144532690
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