Use case
Hi, thank you for working on Powertools.
My Pydantic models are shared between multiple applications. For example, a client application builds an instance of a model and submits it to the API, which validates the request against the same model.
A few types I want to accept as API payloads or parameters are annotated with Field, mainly tagged unions.
I am aware of the Powertools OpenAPI Param annotations, but they have downsides:
- having to import Powertools into non-Lambda projects;
- being stuck with a single
Param type (i.e. Body, Path, etc) per annotated type, or having to duplicate the arguments for different types
With Powertools 3.5.0, the example code below fails:
- with
def create_action(action: Action): AssertionError: Param: action can only be a request body, use Body()
- with
def create_action(action: Annotated[Action, Body()]): AssertionError: Only one FieldInfo can be used per parameter
It would be nice if event_handler would allow nested Field annotations, so that I can apply Annotated[some_type, Body()] to an existing annotated type such as a tagged union.
Thank you for considering.
Solution/User Experience
class FooAction(BaseModel):
action: Literal['foo']
foo: int
class BarAction(BaseModel):
action: Literal['bar']
bar: int
Action = Annotated[FooAction | BarAction, Field(discriminator='action')]
app = APIGatewayHttpResolver(enable_validation=True)
@app.post('/actions')
def create_action(action: Action): # or Annotated[Action, Body()]
...
def lambda_handler(event, context):
return app.resolve(event, context)Alternative solutions
- use event_handler OpenAPI Param annotations exclusively
Action = Annotated[FooAction | BarAction, Body(discriminator='action')]
- use TypeAdapter manually
Action = Annotated[FooAction | BarAction, Field(discriminator='action')]
action_adapter = TypeAdapter(Action)
@app.post('/actions')
def create_action():
try:
action = action_adapter.validate_json(app.current_event.body)
except ValidationError as e:
raise RequestValidationError(e.errors())Acknowledgment
Use case
Hi, thank you for working on Powertools.
My Pydantic models are shared between multiple applications. For example, a client application builds an instance of a model and submits it to the API, which validates the request against the same model.
A few types I want to accept as API payloads or parameters are annotated with
Field, mainly tagged unions.I am aware of the Powertools OpenAPI
Paramannotations, but they have downsides:Paramtype (i.e.Body,Path, etc) per annotated type, or having to duplicate the arguments for different typesWith Powertools 3.5.0, the example code below fails:
def create_action(action: Action):AssertionError: Param: action can only be a request body, use Body()def create_action(action: Annotated[Action, Body()]):AssertionError: Only one FieldInfo can be used per parameterIt would be nice if
event_handlerwould allow nestedFieldannotations, so that I can applyAnnotated[some_type, Body()]to an existing annotated type such as a tagged union.Thank you for considering.
Solution/User Experience
Alternative solutions
Acknowledgment