dynamodbstreams: ApproximateCreationDateTime returns datetime.datetime Instead of timestamp

[RajasGujarathi]

moto version - 5.0.13

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For DynamoDB Streams, dynamodbstreams, I'm encountering an issue with the dynamodbstreams.get_records(ShardIterator=...) method.

Specifically, the response contains a field ApproximateCreationDateTime with a value of datetime.datetime(...), whereas as per AWS docs it is expected to be in ISO 8601 timestamp format.

I get the following response

{'Records': [{'eventID': '7d712df1b71b475da61a2f7aa17c7020', 'eventName': 'INSERT', 'eventVersion': '1.0', 'eventSource': 'aws:dynamodb', 'awsRegion': 'us-east-1', 'dynamodb': {'ApproximateCreationDateTime': datetime.datetime(2024, 8, 27, 15, 16, 17, 606284), .....

Can someone help confirm whether this is a bug or if I am doing something wrong?

[bblommers]

Hi @RajasGujarathi! The HTTP API will indeed send a ISO-8601 string, but boto3 will automatically convert that into a datetime object.
See the boto3-specific API here: https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/dynamodbstreams/client/get_records.html

For background information: Moto actually returns the date in ISO format as well, because we only intercept/mock the actual HTTP response. boto3 still converts the Moto response into a datetime object, like it would do with an actual AWS response.

moto/moto/dynamodbstreams/models.py

Line 92 in 035dfac

"CreationRequestDateTime": table.stream_shard.created_on.isoformat(), # type: ignore[union-attr]