Feature request: alias generator for Query, Path or Header

[tonnico]

Use case

In a BaseModel you can setup an alias_generator.

It would be release nice to have something configurable for e.g. Query

Solution/User Experience

Think about this:

@app.get("/")
def list_something(max_results: Annotated[int, Query(alias="maxResults")]) -> Response[str]:
    ...

could become something like this:

class CamelCaseQuery(Query):
    field_config = {"alias_generator": alias_generators.to_camel}

@app.get("/")
def list_something(max_results: Annotated[int, CamelCaseQuery()]) -> Response[str]:
    ...

Alternative solutions

Acknowledgment

• This feature request meets Powertools for AWS Lambda (Python) Tenets
• Should this be considered in other Powertools for AWS Lambda languages? i.e. Java, TypeScript, and .NET

[leandrodamascena]

Hi @tonnico, thanks for opening this issue! I know about the alias generator in Pydantic, but I might not understand your point here. Can you explain a bit more?

Thanks

[tonnico]

Our default for query parameters is camelCase. It would be nice to setup this without repeating any time with an alias.
Maybe this should be a feature for pydantic FieldInfo?

[leandrodamascena]

Our default for query parameters is camelCase. It would be nice to setup this without repeating any time with an alias. Maybe this should be a feature for pydantic FieldInfo?

Aaa, thanks for explaining the use case, I get it now. The problem here is that Query inherits from FieldInfo and not from BaseModel, so there's no model_config that allows auto-transformation to camelCase. Also, the Pydantic documentation says (search for "camel") that the correct way is to use alias (which is what you're doing). So, yes, I think we can open a feature request in Pydantic.

I tried searching and didn't find anything: https://github.com/pydantic/pydantic/issues?q=sort%3Aupdated-desc%20is%3Aissue%20state%3Aopen%20fieldInfo%20camel

What do you think?

[tonnico]

I think it is not possible to add such information to the type on some way. Probably the best solution would be to add something similar to FastAPI. There you are able to use complete BaseModel's for queries, headers and body.

class Q(BaseModel):
    model_config = {"alias_generator": to_camel}

    my_value: str

@app.get("/")
def list(q: Annotated[Q, Query()]):
    return q.my_value