Set by_alias dynamically when using a schema response?

[stanorama]

Is there a better way to toggle between returning a response with by_alias set.
I have some API clients that require camelCase and some that require snake_case.
The X-Format header can be set to specify which format to return the response in.
However this only works with a response of dict.

If i use the response as the schema, the by_alias attibute set in the router decorator will take prescendence.
I have looked at using a custom renderer, but this seems to too late in the response chain.

The below works, however the repsonse of dict means the open API docs are limited.

@router.post(
    path="/cost_calc/acquisitions",
    response=dict,
    openapi_extra={
        "parameters": [
            {"in": "header", "name": "X-Format", "schema": {"type": "string"}}
        ]
    },
)
def create_acquisition_deal(request: HttpRequest, payload: AcquisitionDealSchema):

    by_alias = request.headers.get("X-Format") == "camel"

    acquisition_deal = AcquisitionDeal.objects.create(
        **payload.model_dump(by_alias=False),
        is_deleted=False,
    )

    return AcquisitionDealSchema.from_orm(acquisition_deal).model_dump(
        by_alias=by_alias
    )

[vitalik]

well you can do something like

from ninja import HeaderEx, P, Router
XFormat = HeaderEx[Literal["camel", "snake"], P(alias="X-Format")]

class AcquisitionDealSchema(Schema):
    model_config = ConfigDict(from_attributes=True, populate_by_name=True)

    deal_name: str = Field(alias="dealName")
    cost: Decimal = Field(alias="cost")



@router.post(path="/acquisitions", response=dict)
def create_acquisition_deal(request, payload: AcquisitionDealSchema, x_format: XFormat = None):
    by_alias = x_format == "camel"

    acquisition_deal = AcquisitionDeal.objects.create(
        **payload.model_dump(by_alias=False),
        is_deleted=False,
    )

    return AcquisitionDealSchema.from_orm(acquisition_deal).model_dump(
        by_alias=by_alias,
    )

making reusable XFormat instead of openapi_extra

as for return - I guess response=dict for now

I'll think how can we adapt it between result and renderer

[stanorama]

Thanks @vitalik. The route header declaration is useful to know.

I am adding the header to all routes via the NinjaAPI. i.e.

class NinjaWithExtra(NinjaAPI):
    def get_openapi_schema(self, *args, **kwargs):
        schema = super().get_openapi_schema(*args, **kwargs)
        paths = schema.get("paths", {})
        for _, methods in paths.items():
            for _, details in methods.items():
                parameters = details.get("parameters", [])
                parameters.append(
                    {
                        "in": "header",
                        "name": "X-format",
                        "schema": {"type": "string"},
                        "description": "Optional header to specify camelCase format. Set to 'camel' to enable camelCase formatting.",
                    }
                )
                details["parameters"] = parameters

        return schema

For reference for any other readers.
With the pydantic config, that will change in v3 (populate_by_name is deprecated), so the future proof way is something like this...

from pydantic import AliasGenerator, ConfigDict
from pydantic.alias_generators import to_camel


class CamelCaseSchema(Schema):
    model_config = ConfigDict(
        alias_generator=AliasGenerator(
            validation_alias=to_camel, serialization_alias=to_camel
        ),
        serialize_by_alias=True,
        validate_by_name=True,
        validate_by_alias=True,
        from_attributes=True,
    )

I will continue to use the dict repsonse type for now. Thanks again.