* 如果你还在一个具体的*路径操作*中声明了依赖项，**它们也会被执行**。
    * 路由器的依赖项最先执行，然后是[装饰器中的 `dependencies`](dependencies/dependencies-in-path-operation-decorators.md){.internal-link target=_blank}，再然后是普通的参数依赖项。
    * 你还可以添加[具有 `scopes` 的 `Security` 依赖项](../advanced/security/oauth2-scopes.md){.internal-link target=_blank}。

/// tip

在 `APIRouter`中具有 `dependencies` 可以用来，例如，对一整组的*路径操作*要求身份认证。即使这些依赖项并没有分别添加到每个路径操作中。

///

/// check

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* Security and authentication, including support for **OAuth2** with **JWT tokens** and **HTTP Basic** auth.
* More advanced (but equally easy) techniques for declaring **deeply nested JSON models** (thanks to Pydantic).
* **GraphQL** integration with <a href="https://strawberry.rocks" class="external-link" target="_blank">Strawberry</a> and other libraries.

def read_user(user_id: int, db: Session = Depends(get_db)):
    db_user = crud.get_user(db, user_id=user_id)
    ...
```

/// info

🚥 👆 💪 🔗 👆 🔗 💽 🔁, 👀 [🔁 🗄 (🔗) 💽](../advanced/async-sql-databases.md){.internal-link target=_blank}.

///

/// note | "📶 📡 ℹ"

🚥 👆 😟 & ✔️ ⏬ 📡 💡, 👆 💪 ✅ 📶 📡 ℹ ❔ 👉 `async def` 🆚 `def` 🍵 [🔁](../async.md#i_2){.internal-link target=_blank} 🩺.

    Read more about it in the
    [FastAPI docs for Security](https://fastapi.tiangolo.com/tutorial/security/) and
    in the
    [FastAPI docs for OAuth2 scopes](https://fastapi.tiangolo.com/advanced/security/oauth2-scopes/).

    **Example**

    ```python
    from typing import Annotated

    from fastapi import Security, FastAPI

    from .db import User

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   * uncommon to specify {@code concurrencyLevel(1)} in order to achieve more deterministic eviction
   * behavior.
   *
   * <p>Note that future implementations may abandon segment locking in favor of more advanced
   * concurrency controls.
   *
   * @return this {@code CacheBuilder} instance (for chaining)
   * @throws IllegalArgumentException if {@code concurrencyLevel} is nonpositive

⛔️ **Shell** form:

```Dockerfile
# ⛔️ Don't do this
CMD fastapi run app/main.py --port 80
```

Make sure to always use the **exec** form to ensure that FastAPI can shutdown gracefully and [lifespan events](../advanced/events.md){.internal-link target=_blank} are triggered.

    db_user = crud.get_user(db, user_id=user_id)
    ...
```

/// info

如果您需要异步连接到关系数据库，请参阅[Async SQL (Relational) Databases](https://fastapi.tiangolo.com/zh/advanced/async-sql-databases/)

///

/// note | "Very Technical Details"

如果您很好奇并且拥有深厚的技术知识，您可以在[Async](https://fastapi.tiangolo.com/zh/async/#very-technical-details)文档中查看有关如何处理 `async def`于`def`差别的技术细节。

///