## Dependency Injection

Using `BackgroundTasks` also works with the dependency injection system, you can declare a parameter of type `BackgroundTasks` at multiple levels: in a *path operation function*, in a dependency (dependable), in a sub-dependency, etc.

**FastAPI** knows what to do in each case and how to re-use the same object, so that all the background tasks are merged together and are run in the background afterwards:

=== "Python 3.10+"

        **extra,
    )


def Depends(  # noqa: N802
    dependency: Annotated[
        Optional[Callable[..., Any]],
        Doc(
            """
            A "dependable" callable (like a function).

            Don't call it directly, FastAPI will call it for you, just pass the object
            directly.
            """
        ),
    ] = None,
    *,

Bevor wir tiefer in das **Dependency Injection** System eintauchen, lassen Sie uns das vorherige Beispiel verbessern.

## Ein `dict` aus dem vorherigen Beispiel

Im vorherigen Beispiel haben wir ein `dict` von unserer Abhängigkeit („Dependable“) zurückgegeben:

=== "Python 3.10+"

    ```Python hl_lines="9"
    {!> ../../../docs_src/dependencies/tutorial001_an_py310.py!}
    ```

=== "Python 3.9+"

    ```Python hl_lines="11"

**FastAPI** weiß, was jeweils zu tun ist und wie dasselbe Objekt wiederverwendet werden kann, sodass alle Hintergrundtasks zusammengeführt und anschließend im Hintergrund ausgeführt werden:

     * address, isPermanent, isBeingDeleted, ...etc. This information can only
     * be retrieved with the Node Status request.
     * 
     * The degree of state that an NbtAddress has is dependant on how it was
     * created and what is required of it. The second degree of state is the
     * most common. This is the state information that would be retrieved from

# 依存関係としてのクラス

**依存性注入** システムを深く掘り下げる前に、先ほどの例をアップグレードしてみましょう。

## 前の例の`dict`

前の例では、依存関係（"dependable"）から`dict`を返していました:

```Python hl_lines="9"
{!../../../docs_src/dependencies/tutorial001.py!}
```

しかし、*path operation関数*のパラメータ`commons`に`dict`が含まれています。

また、エディタは`dict`のキーと値の型を知ることができないため、多くのサポート（補完のような）を提供することができません。

もっとうまくやれるはずです...。

## 依存関係を作るもの

これまでは、依存関係が関数として宣言されているのを見てきました。

bhack, Brendan Collins, Can Wang, Cheng Ren, Chris Leary, Chris Olivier, Clemens
Giuliani, Cloud Han, Corey Cole, Cui, Yifeng, Cuong V. Nguyen, Daniel Moore,
Dawid Wojciechowski, Ddavis-2015, Dean Wyatte, Denisa Roberts, dependabot[bot],
Dmitry Volodin, Dominic Jack, Duncan Riach, dushuai, Elena Zhelezina, Eli
Osherovich, Erik Smistad, ewsn1593, Felix Fent, fo40225, François Chollet,

                    } else {
                        out[j++] = ch;
                    }
                    break;
                case 1:
                    /* Get ASCII hex value and convert to platform dependant
                     * encoding like EBCDIC perhaps
                     */
                    b[0] = (byte)(Integer.parseInt( str.substring( i, i + 2 ), 16 ) & 0xFF);

 * address, isPermanent, isBeingDeleted, ...etc. This information can only
 * be retrieved with the Node Status request.
 * 
 * The degree of state that an NbtAddress has is dependant on how it was
 * created and what is required of it. The second degree of state is the
 * most common. This is the state information that would be retrieved from

### Tools. Gradle. Cocoapods

- [`KT-38749`](https://youtrack.jetbrains.com/issue/KT-38749) Support reusing generated C-interop between dependant pods
- [`KT-54161`](https://youtrack.jetbrains.com/issue/KT-54161) Support adding extra code to generated Podfile from the Kotlin gradle plugin