def test_app_path_operation_overrides_generate_unique_id():
    app = FastAPI(generate_unique_id_function=custom_generate_unique_id)
    router = APIRouter(generate_unique_id_function=custom_generate_unique_id2)

    @app.post(
        "/",
        response_model=List[Item],
        responses={404: {"model": List[Message]}},
        generate_unique_id_function=custom_generate_unique_id3,
    )

In this case you will have to ensure that each operation ID is **unique** in some other way.

For example, you could make sure that each *path operation* has a tag, and then generate the operation ID based on the **tag** and the *path operation* **name** (the function name).

### Custom Generate Unique ID Function

    tags: Set[str] = set()


@app.post(
    "/items/",
    response_model=Item,
    summary="Create an item",
    description="Create an item with all the information, name, description, price, tax and a set of unique tags",
)
async def create_item(item: Item):

    - **name**: each item must have a name
    - **description**: a long description
    - **price**: required
    - **tax**: if the item doesn't have tax, you can omit this
    - **tags**: a set of unique tag strings for this item
    """

    - **name**: each item must have a name
    - **description**: a long description
    - **price**: required
    - **tax**: if the item doesn't have tax, you can omit this
    - **tags**: a set of unique tag strings for this item
    """

    - **name**: each item must have a name
    - **description**: a long description
    - **price**: required
    - **tax**: if the item doesn't have tax, you can omit this
    - **tags**: a set of unique tag strings for this item
    \f
    :param item: User input.
    """

    )
    operation_id = f"{name}{path}"
    operation_id = re.sub(r"\W", "_", operation_id)
    operation_id = f"{operation_id}_{method.lower()}"
    return operation_id


def generate_unique_id(route: "APIRoute") -> str:
    operation_id = f"{route.name}{route.path_format}"
    operation_id = re.sub(r"\W", "_", operation_id)
    assert route.methods

                """
            ),
        ] = None,
        generate_unique_id_function: Annotated[
            Callable[[routing.APIRoute], str],
            Doc(
                """
                Customize the function used to generate unique IDs for the *path
                operations* shown in the generated OpenAPI.

from typing import List

from fastapi import FastAPI
from fastapi.routing import APIRoute
from pydantic import BaseModel


def custom_generate_unique_id(route: APIRoute):
    return f"{route.tags[0]}-{route.name}"


app = FastAPI(generate_unique_id_function=custom_generate_unique_id)


class Item(BaseModel):
    name: str
    price: float


class ResponseMessage(BaseModel):
    message: str

        if isinstance(generate_unique_id_function, DefaultPlaceholder):
            current_generate_unique_id: Callable[
                ["APIRoute"], str
            ] = generate_unique_id_function.value
        else:
            current_generate_unique_id = generate_unique_id_function
        self.unique_id = self.operation_id or current_generate_unique_id(self)
        # normalize enums e.g. http.HTTPStatus