Bug: APIGatewayProxyEventV2Model not deserializing str to custom model

Expected Behaviour

It should be possible to use own model classes for body in APIGatewayProxyEventV2Model

Current Behaviour

When I extend APIGatewayProxyEventV2Model model to include my own model for the body following exception is raised 1 validation error for Event\nbody\n value is not a valid dict (type=type_error.dict). I suppose the reason for that is that body of apigw v2 event is a string

Code snippet

from aws_lambda_powertools.utilities.parser import BaseModel
from aws_lambda_powertools.utilities.parser.models import (
    APIGatewayProxyEventV2Model
)


class OrderCancelationRequest(BaseModel):
    reason: str
    orderNo: str


class MyEventModel(APIGatewayProxyEventV2Model):
    body: OrderCancelationRequest

Possible Solution

No response

Steps to Reproduce

parse(model=MyEventModel, event=any valid apigw event)

AWS Lambda Powertools for Python version

latest

AWS Lambda function runtime

3.9

Packaging format used

PyPi

Debugging logs

No response

[nleipi]

I think the correct way to handle this is to use pydantics own Json type as a wrapper for the model.

class MyEventModel(APIGatewayProxyEventV2Model):
    body: Json[OrderCancelationRequest]

That should be definitely highlighted in the documentation.

[rubenfonseca]

Thank you so much for your input! I’ve opened a PR now to add this use case to our parser docs 😃