if not isinstance(v, StarletteUploadFile):
            raise ValueError(f"Expected UploadFile, received: {type(v)}")
        return v

    @classmethod
    def _validate(cls, __input_value: Any, _: Any) -> "UploadFile":
        if not isinstance(__input_value, StarletteUploadFile):
            raise ValueError(f"Expected UploadFile, received: {type(__input_value)}")

    async def __call__(self, request: Request) -> Optional[str]:
        authorization = request.headers.get("Authorization")
        if not authorization:
            if self.auto_error:
                raise HTTPException(
                    status_code=HTTP_403_FORBIDDEN, detail="Not authenticated"
                )
            else:
                return None

def main() -> None:
    if not cli_main:  # type: ignore[truthy-function]
        message = 'To use the fastapi command, please install "fastapi[standard]":\n\n\tpip install "fastapi[standard]"\n'
        print(message)
        raise RuntimeError(message)  # noqa: B904

list](https://groups.google.com/forum/#!forum/golang-nuts) or [other forums](https://golang.org/help/) first. If
the behavior you are seeing is confirmed as a bug or issue, it can easily be re-raised in the issue tracker.

## Filing issues

Sensitive security-related issues should be reported to [******@****.***](mailto:******@****.***).
See the [security policy](https://golang.org/security) for details.

from fastapi import FastAPI, HTTPException

app = FastAPI()

items = {"foo": "The Foo Wrestlers"}


@app.get("/items/{item_id}")
async def read_item(item_id: str):
    if item_id not in items:
        raise HTTPException(status_code=404, detail="Item not found")

# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# Run go tool dist to install a command.
# The -v causes dist to print the name of each directory as it runs.
# The -vv causes dist to print each build command as it runs.
# go tool dist clean cleans all directories, not just this one,
# but it's as close as we can get.

# Default target (first).
install:

/// tip

Prefer to use the `Annotated` version if possible.

///

```Python hl_lines="6  11"
{!> ../../docs_src/dependencies/tutorial006.py!}
```

////

### Raise exceptions

These dependencies can `raise` exceptions, the same as normal dependencies:

//// tab | Python 3.9+

```Python hl_lines="10  15"
{!> ../../docs_src/dependencies/tutorial006_an_py39.py!}
```

////

async def validation_exception_handler(request, exc):
    return PlainTextResponse(str(exc), status_code=400)


@app.get("/items/{item_id}")
async def read_item(item_id: int):
    if item_id == 3:
        raise HTTPException(status_code=418, detail="Nope! I don't like 3.")

    correct_password_bytes = b"swordfish"
    is_correct_password = secrets.compare_digest(
        current_password_bytes, correct_password_bytes
    )
    if not (is_correct_username and is_correct_password):
        raise HTTPException(
            status_code=status.HTTP_401_UNAUTHORIZED,
            detail="Incorrect username or password",
            headers={"WWW-Authenticate": "Basic"},
        )
    return credentials.username

    async def __call__(self, request: Request) -> Optional[str]:
        authorization = request.headers.get("Authorization")
        if not authorization:
            if self.auto_error:
                raise HTTPException(
                    status_code=HTTP_403_FORBIDDEN, detail="Not authenticated"
                )
            else:
                return None
        return authorization