Converting schema field names from snake_case

[janbuchar]

I have an API that returns objects whose fields have snake_case names. openapi-generator can convert those to camelCase for me when I use it to generate typescript interfaces. Can Orval do something similar?

[anymaniax]

Not at the moment, the only solution is to use a mutator that transforms the data of your API and a transformer to transform all your types in camelCase. But could be a good feature to add

[janbuchar]

Thanks! The solution you describe seems feasible, even though baking the conversion into the generated code might be more convenient.

[janbuchar]

I experimented with the suggested solution and found a possible pitfall. When the API produces free-form key-value structures (type:object with additionalProperties), the mutator will update these as well, which is certainly unexpected.

[jordan-rigo]

Iam having the same issue. Did you find a working solution for this?

[janbuchar]

Unfortunately, no. Except the old-fashioned openapi-generator, which lacks a lot of features, I haven't found this functionality in any OpenAPI code generator. It's frustrating and I'd be very happy if you could share your results should you find something 🙂

[devraj]

We have a similar situation our API built in python with FastAPI has snake_case function and variables names and they are converted to camelCase without needing orval do anything extra.

FastAPI allow us to provide a method that can return the operation_id:

def generate_operation_id(route: APIRoute) -> str:
    """
        With a little help from FastAPI docs
        https://bit.ly/3rXeAvH

        Globally use the path name as the operation id thus
        making things a lot more readable, note that this requires
        you name your functions really well.

        Read  more about this on the FastAPI docs
        https://shorturl.at/vwz03
    """
    return route.name

and then configuration FastAPI to use this function:

app = FastAPI(
    generate_unique_id_function=generate_operation_id,
    ....
)

FastAPI is tightly coupled with pyndatic, which can be configured to translate these:

def to_lower_camel(name: str) -> str:
    """
    Converts a snake_case string to lowerCamelCase
    """
    upper = "".join(word.capitalize() for word in name.split("_"))
    return upper[:1].lower() + upper[1:]


class AppBaseModel(BaseModel):
    """ Pydantic base model for applications

    This class is used to define the base model for all schema
    that we use in the Application, it configures pydantic to
    translate between camcelCase and snake_case for the JSON
    amongst other default settings.

    populate_by_name will allow pydantic to translate SQLAlchemy 
    results into serializable models, while being able to translate
    the aliases back to the original names when serializing to JSON.

    For a full set of options, see:
    https://pydantic-docs.helpmanual.io/usage/model_config/
    """
    model_config = ConfigDict(
        populate_by_name=True,
        alias_generator=to_lower_camel,
    )

The solution is specific to python and fastapi but hopefully of some use in finding a relevant path forward.