from typing_extensions import Annotated, Doc


class OAuth2PasswordRequestForm:
    """
    This is a dependency class to collect the `username` and `password` as form data
    for an OAuth2 password flow.

    The OAuth2 specification dictates that for a password flow the data should be
    collected using form data (instead of JSON) and that it should have the specific
    fields `username` and `password`.

If you added the return type annotation, tools and editors would complain with a (correct) error telling you that your function is returning a type (e.g. a dict) that is different from what you declared (e.g. a Pydantic model).

```

but this time at the URL with the prefix path provided by the proxy: `/api/v1`.

Of course, the idea here is that everyone would access the app through the proxy, so the version with the path prefix `/api/v1` is the "correct" one.

And the version without the path prefix (`http://127.0.0.1:8000/app`), provided by Uvicorn directly, would be exclusively for the _proxy_ (Traefik) to access it.

```

#### 注意

参数:

```Python
connect_args={"check_same_thread": False}
```

...仅用于`SQLite`，在其他数据库不需要它。

!!! info "技术细节"

    默认情况下，SQLite 只允许一个线程与其通信，假设有多个线程的话，也只将处理一个独立的请求。

    这是为了防止意外地为不同的事物（不同的请求）共享相同的连接。

    但是在 FastAPI 中，普遍使用def函数，多个线程可以为同一个请求与数据库交互，所以我们需要使用`connect_args={"check_same_thread": False}`来让SQLite允许这样。

                    "type": "value_error.str.regex",
                    "ctx": {"pattern": "password"},
                }
            ]
        }
    )


def test_strict_login_correct_data():
    response = client.post(
        "/login",
        data={"username": "johndoe", "password": "secret", "grant_type": "password"},
    )
    assert response.status_code == 200

And open the docs at <a href="http://127.0.0.1:8000/docs" class="external-link" target="_blank">http://127.0.0.1:8000/docs</a>.

You will see the automatic API docs, including the paths from all the submodules, using the correct paths (and prefixes) and the correct tags:

<img src="/img/tutorial/bigger-applications/image01.png">

## Include the same router multiple times with different `prefix`

<img src="/img/deployment/https/https07.svg">

The client (browser) will know that the response comes from the correct server because it is using the cryptography they agreed using the **HTTPS certificate** before.

### Multiple Applications

```

#### 🗒

❌:

```Python
connect_args={"check_same_thread": False}
```

...💪 🕴 `SQLite`. ⚫️ 🚫 💪 🎏 💽.

!!! info "📡 ℹ"

    🔢 🗄 🔜 🕴 ✔ 1️⃣ 🧵 🔗 ⏮️ ⚫️, 🤔 👈 🔠 🧵 🔜 🍵 🔬 📨.

    👉 ❎ 😫 🤝 🎏 🔗 🎏 👜 (🎏 📨).

    ✋️ FastAPI, ⚙️ 😐 🔢 (`def`) 🌅 🌘 1️⃣ 🧵 💪 🔗 ⏮️ 💽 🎏 📨, 👥 💪 ⚒ 🗄 💭 👈 ⚫️ 🔜 ✔ 👈 ⏮️ `connect_args={"check_same_thread": False}`.

Mais ensuite, même si vous n'avez pas encore vos burgers 🍔, votre travail avec le serveur 💁 est "en pause" ⏸, car vous devez attendre 🕙 que vos burgers soient prêts.

Whenever a new request arrives, **FastAPI** will take care of:

* Calling your dependency ("dependable") function with the correct parameters.
* Get the result from your function.
* Assign that result to the parameter in your *path operation function*.

```mermaid
graph TB

common_parameters(["common_parameters"])