Camelize FastAPI path params and query params.

fastapi_camel.py

"""
Camelize FastAPI path params and query params.

For body params and responses, use pydantic model's alias_generator config.
"""

from fastapi import FastAPI
from fastapi.dependencies.models import Dependant
from fastapi.routing import APIRoute
from humps import camelize
from starlette.routing import compile_path


def camelize_app(
    app: FastAPI,
    path_params: bool = True,
    query_params: bool = True,
):
    routes = [route for route in app.routes if isinstance(route, APIRoute)]

    if path_params:
        for route in routes:
            _camelize_path_params(route.dependant)
            _recompile_path(route)

    if query_params:
        for route in routes:
            _camelize_query_params(route.dependant)


def _camelize_path_params(dependant: Dependant):
    for param in dependant.path_params:
        param.alias = camelize(param.name)
        if dependant.path:
            dependant.path = dependant.path.replace(f"{{{param.name}}}", f"{{{param.alias}}}")

    for sub_dependant in dependant.dependencies:
        _camelize_path_params(sub_dependant)


def _camelize_query_params(dependant: Dependant):
    for param in dependant.query_params:
        param.alias = camelize(param.name)

    for sub_dependant in dependant.dependencies:
        _camelize_query_params(sub_dependant)


def _recompile_path(route: APIRoute):
    if not route.dependant.path:
        return
    route.path = route.dependant.path
    route.path_regex, route.path_format, route.param_convertors = compile_path(route.path)