# Security - First Steps

Let's imagine that you have your **backend** API in some domain.

And you have a **frontend** in another domain or in a different path of the same domain (or in a mobile application).

And you want to have a way for the frontend to authenticate with the backend, using a **username** and **password**.

We can use **OAuth2** to build that with **FastAPI**.

在这个例子中，它是一个 `async` 函数。

---

你也可以将其定义为常规函数而不使用 `async def`:

```Python hl_lines="7"
{!../../../docs_src/first_steps/tutorial003.py!}
```

!!! note
    如果你不知道两者的区别，请查阅 [Async: *"In a hurry?"*](https://fastapi.tiangolo.com/async/#in-a-hurry){.internal-link target=_blank}。

### 步骤 5：返回内容

```Python hl_lines="8"
{!../../../docs_src/first_steps/tutorial001.py!}
```

你可以返回一个 `dict`、`list`，像 `str`、`int` 一样的单个值，等等。

!!! note "Teknik Detaylar"
    `FastAPI` doğrudan `Starlette`'i miras alan bir sınıftır.

    <a href="https://www.starlette.io/" class="external-link" target="_blank">Starlette</a>'in tüm işlevselliğini `FastAPI` ile de kullanabilirsiniz.

### Adım 2: Bir `FastAPI` "Örneği" Oluşturalım

```Python hl_lines="3"
{!../../../docs_src/first_steps/tutorial001.py!}
```

    Alle Sicherheits-Werkzeuge, die in OpenAPI integriert sind (und die automatische API-Dokumentation), erben von `SecurityBase`, so weiß **FastAPI**, wie es sie in OpenAPI integrieren muss.

## Was es macht

```Python hl_lines="7"
{!../../../docs_src/first_steps/tutorial003.py!}
```

!!! note
    Jeśli nie znasz różnicy, sprawdź [Async: *"In a hurry?"*](../async.md#in-a-hurry){.internal-link target=_blank}.

### Krok 5: zwróć zawartość

```Python hl_lines="8"
{!../../../docs_src/first_steps/tutorial001.py!}
```

```Python hl_lines="7"
{!../../../docs_src/first_steps/tutorial003.py!}
```

!!! note
    Nếu bạn không biết sự khác nhau, kiểm tra [Async: *"Trong khi vội vàng?"*](../async.md#in-a-hurry){.internal-link target=_blank}.

### Bước 5: Nội dung trả về

```Python hl_lines="8"
{!../../../docs_src/first_steps/tutorial001.py!}
```

In diesem Fall handelt es sich um eine `async`-Funktion.

---

Sie könnten sie auch als normale Funktion anstelle von `async def` definieren:

```Python hl_lines="7"
{!../../../docs_src/first_steps/tutorial003.py!}
```

!!! note "Hinweis"
    Wenn Sie den Unterschied nicht kennen, lesen Sie [Async: *„In Eile?“*](../async.md#in-eile){.internal-link target=_blank}.

In this case, it is an `async` function.

---

You could also define it as a normal function instead of `async def`:

```Python hl_lines="7"
{!../../../docs_src/first_steps/tutorial003.py!}
```

!!! note
    If you don't know the difference, check the [Async: *"In a hurry?"*](../async.md#in-a-hurry){.internal-link target=_blank}.