path_params=dependant.path_params.copy(),
        query_params=dependant.query_params.copy(),
        header_params=dependant.header_params.copy(),
        cookie_params=dependant.cookie_params.copy(),
        body_params=dependant.body_params.copy(),
        name=dependant.name,
        call=dependant.call,
        request_param_name=dependant.request_param_name,

async def run_endpoint_function(
    *, dependant: Dependant, values: dict[str, Any], is_coroutine: bool
) -> Any:
    # Only called by get_request_handler. Has been split into its own function to
    # facilitate profiling endpoints, since inner functions are harder to profile.
    assert dependant.call is not None, "dependant.call must be a function"

    if is_coroutine:

def _get_openapi_operation_parameters(
    *,
    dependant: Dependant,
    model_name_map: ModelNameMap,
    field_mapping: dict[
        tuple[ModelField, Literal["validation", "serialization"]], dict[str, Any]
    ],
    separate_input_output_schemas: bool = True,
) -> list[dict[str, Any]]:
    parameters = []
    flat_dependant = get_flat_dependant(dependant, skip_repeats=True)

    ] = None,
    *,
    use_cache: Annotated[
        bool,
        Doc(
            """
            By default, after a dependency is called the first time in a request, if
            the dependency is declared again for the rest of the request (for example
            if the dependency is needed by several dependencies), the value will be
            re-used for the rest of the request.

from pydantic import BaseModel

app = FastAPI()

client = TestClient(app)


class Item(BaseModel):
    data: str


def duplicate_dependency(item: Item):
    return item


def dependency(item2: Item):
    return item2


def sub_duplicate_dependency(
    item: Item, sub_item: Item = Depends(duplicate_dependency)
):
    return [item, sub_item]


@app.post("/with-duplicates")

      - name: Set up Python
        uses: actions/setup-python@v6
        with:
          python-version: "3.11"
      - name: Setup uv
        uses: astral-sh/setup-uv@v7
        with:
          cache-dependency-glob: |
            requirements**.txt
            pyproject.toml
      - name: Install Dependencies
        run: uv pip install -r requirements-github-actions.txt -r requirements-translations.txt

        with:
          python-version: ${{ matrix.python-version }}
      - name: Setup uv
        uses: astral-sh/setup-uv@v7
        with:
          version: "0.4.15"
          enable-cache: true
          cache-dependency-glob: |
            requirements**.txt
            pyproject.toml
      - name: Install Dependencies
        run: uv pip install -r requirements-tests.txt
      - run: mkdir coverage
      - name: Test

class FastAPIError(RuntimeError):
    """
    A generic, FastAPI-specific error.
    """


class DependencyScopeError(FastAPIError):
    """
    A dependency declared that it depends on another dependency with an invalid
    (narrower) scope.
    """


class ValidationException(Exception):
    def __init__(
        self,
        errors: Sequence[Any],
        *,

      - name: Set up Python
        uses: actions/setup-python@v6
        with:
          python-version: "3.14"
      - name: Setup uv
        uses: astral-sh/setup-uv@v7
        with:
          cache-dependency-glob: |
            requirements**.txt
            pyproject.toml
            uv.lock
      - name: Install Dependencies
        run: |
          uv venv
          uv pip install -r requirements.txt

Depending on your use case, you might prefer to use a different library, but if you asked me, I would probably suggest you try **Strawberry**.

Here's a small preview of how you could integrate Strawberry with FastAPI: