How do you handle type annotations in the backend classes?

[andresliszt]

I recently submitted a PR #9856. I will take as example the create_event method of Bedrock Agent Core. The argument clientToken is optional in boto3 but it is autogenerated if not provided This field is autopopulated if not provided.. Therefore in boto3 is clientToken: str | None but in the corresponding backend class is client_token: str, because backend always expects to get the autogenerated token if it was not provided. Is that true right?

[bblommers]

Hi @andresliszt, that sounds right.

In general we don't really look at boto3 when determining the attribute types in Moto because of this. There are quite a few classes of attribute types where what boto3 uses is not relevant to us:

• boto3 required str | None, but because it's autopopulated (automatically generated) if not provided, Moto can use str
• boto3 requires str | None, but AWS/Moto uses a default value if not provided, therefore we always type it as a str
• boto3 might require a datetime, but parses it automatically and Moto receives it as a timestamp representation (int)

So in short - the type annotations in the backend classes are only guided by what makes sense, not by what boto3 provides.