它的属性 `scopes`  是作用域列表，所有依赖项都把它作为子依赖项。也就是说所有**依赖**……这听起来有些绕，后文会有解释。

（类 `SecurityScopes` 的）`security_scopes` 对象还提供了单字符串类型的属性 `scope_str`，该属性是（要在本例中使用的）用空格分割的作用域。

此处还创建了后续代码中要复用（`raise`）的 `HTTPException` 。

该异常包含了作用域所需的（如有），以空格分割的字符串（使用 `scope_str`）。该字符串要放到包含作用域的 `WWW-Authenticate` 请求头中（这也是规范的要求）。

```Python hl_lines="105  107-115"
{!../../../docs_src/security/tutorial005.py!}
```

Wir erstellen eine `HTTPException`, die wir später an mehreren Stellen wiederverwenden (`raise`n) können.

Und Sie möchten diese Exception global mit FastAPI handhaben.

Sie könnten einen benutzerdefinierten Exceptionhandler mittels `@app.exception_handler()` hinzufügen:

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

Wenn Sie nun `/unicorns/yolo` anfragen, `raise`d die *Pfadoperation* eine `UnicornException`.

The `security_scopes` object (of class `SecurityScopes`) also provides a `scope_str` attribute with a single string, containing those scopes separated by spaces (we are going to use it).

We create an `HTTPException` that we can re-use (`raise`) later at several points.

But then, even though you still don't have your burgers, your work with the cashier is "on pause" ⏸, because you have to wait 🕙 for your burgers to be ready.

##### Nouvelle langue non prise en charge

Si, lors de l'exécution du script du serveur en direct, vous obtenez une erreur indiquant que la langue n'est pas prise en charge, quelque chose comme :

```
 raise TemplateNotFound(template)
jinja2.exceptions.TemplateNotFound: partials/language/xx.html
```

Cela signifie que le thème ne supporte pas cette langue (dans ce cas, avec un faux code de 2 lettres de `xx`).

So, in our case, if we set the Peewee state variable (with a default `dict`) in the `async` dependency, all the rest of the internal code in our app will see this value and will be able to reuse it for the whole request.

And the context variable would be set again for the next request, even if they are concurrent.

### Set database state in the dependency `get_db()`

# Exceptions - `HTTPException` and `WebSocketException`

These are the exceptions that you can raise to show errors to the client.

When you raise an exception, as would happen with normal Python, the rest of the execution is aborted. This way you can raise these exceptions from anywhere in the code to abort a request and show the error to the client.

You can use:

* `HTTPException`
* `WebSocketException`

    Note over client,tasks: Can raise exception for dependency, handled after response is sent
    Note over client,operation: Can raise HTTPException and can change the response
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise
        dep -->> handler: Raise HTTPException
        handler -->> client: HTTP error response
        dep -->> dep: Raise other exception
    end

    Note over client,tasks: Can raise exception for dependency, handled after response is sent
    Note over client,operation: Can raise HTTPException and can change the response
    client ->> dep: Start request
    Note over dep: Run code up to yield
    opt raise
        dep -->> handler: Raise HTTPException
        handler -->> client: HTTP error response
        dep -->> dep: Raise other exception
    end