Then one the last requests that wait less seconds will try to open a database connection, but as one of those previous requests for the other tabs will probably be handled in the same thread as the first one, it will have the same database connection that is already open, and Peewee will throw an error and you will see it in the terminal, and the response will have an `Internal Server Error`.

    It's almost the only thing that you have to remember to do correctly yourself, to be compliant with the specifications.

    For the rest, **FastAPI** handles it for you.

## Update the dependencies

Now we are going to update our dependencies.

We want to get the `current_user` *only* if this user is active.

        @classmethod
        def __get_pydantic_json_schema__(
            cls, core_schema: CoreSchema, handler: GetJsonSchemaHandler
        ) -> JsonSchemaValue:
            return {"type": "string", "format": "email"}

        @classmethod
        def __get_pydantic_core_schema__(
            cls, source: Type[Any], handler: Callable[[Any], CoreSchema]
        ) -> CoreSchema:

    * In requests and responses will be treated as `str`.
    * The generated schema will specify that it's a `str` with `binary` "format".
* `Decimal`:
    * Standard Python `Decimal`.
    * In requests and responses, handled the same as a `float`.
* You can check all the valid pydantic data types here: <a href="https://docs.pydantic.dev/latest/usage/types/types/" class="external-link" target="_blank">Pydantic data types</a>.

## Example

!!! note
    You don't necessarily need to add different scopes in different places.

    We are doing it here to demonstrate how **FastAPI** handles scopes declared at different levels.

=== "Python 3.10+"

    ```Python hl_lines="4  139  170"
    {!> ../../../docs_src/security/tutorial005_an_py310.py!}
    ```

=== "Python 3.9+"

`secrets.compare_digest()` needs to take `bytes` or a `str` that only contains ASCII characters (the ones in English), this means it wouldn't work with characters like `á`, as in `Sebastián`.

To handle that, we first convert the `username` and `password` to `bytes` encoding them with UTF-8.

        ),
    ] = "https://fastapi.tiangolo.com/img/favicon.png",
    oauth2_redirect_url: Annotated[
        Optional[str],
        Doc(
            """
            The OAuth2 redirect URL, it is normally automatically handled by FastAPI.
            """
        ),
    ] = None,
    init_oauth: Annotated[
        Optional[Dict[str, Any]],
        Doc(
            """

An alternative JSON response using <a href="https://github.com/ultrajson/ultrajson" class="external-link" target="_blank">`ujson`</a>.

!!! warning
    `ujson` is less careful than Python's built-in implementation in how it handles some edge-cases.

```Python hl_lines="2  7"
{!../../../docs_src/custom_response/tutorial001.py!}
```

!!! tip
    It's possible that `ORJSONResponse` might be a faster alternative.

    These are very technical details of how **FastAPI** works underneath.

    If you have quite some technical knowledge (coroutines, threads, blocking, etc.) and are curious about how FastAPI handles `async def` vs normal `def`, go ahead.

### Path operation functions

Можно добавить собственный обработчик исключений с помощью `@app.exception_handler()`:

```Python hl_lines="5-7  13-18  24"
{!../../../docs_src/handling_errors/tutorial003.py!}
```

Здесь, если запросить `/unicorns/yolo`, то *операция пути* вызовет `UnicornException`.

Но оно будет обработано `unicorn_exception_handler`.

Таким образом, вы получите чистую ошибку с кодом состояния HTTP `418` и содержимым JSON: