* ♻️ Refactor internals of dependencies, simplify code and remove `get_param_sub_dependant`. PR [#14255](https://github.com/fastapi/fastapi/pull/14255) by [@tiangolo](https://github.com/tiangolo).

description: FastAPI best practices and conventions. Use when working with FastAPI APIs and Pydantic models for them. Keeps FastAPI code clean and up to date with the latest features and patterns, updated with new versions. Write new code or refactor and update old code.
---

# FastAPI

Official FastAPI skill to write code with best practices, keeping up to date with new versions and features.

## Use the `fastapi` CLI

Later you will see how **powerful** it can be.

/// tip

The fact that this is **standard Python** means that you will still get the **best possible developer experience** in your editor, with the tools you use to analyze and refactor your code, etc. ✨

And also that your code will be very compatible with many other Python tools and libraries. 🚀

///

## Type hints in **FastAPI** { #type-hints-in-fastapi }

// 現在就可以讀取到環境變數了

Hello Wade Wilson from Python

// 在此之後這個環境變數將不再存在
$ python main.py

Hello World from Python
```

</div>

/// tip

你可以在 [The Twelve-Factor App: 配置](https://12factor.net/config) 中了解更多資訊。

///

## 型別和驗證 { #types-and-validation }

這些環境變數只能處理**文字字串**，因為它們是位於 Python 範疇之外的，必須與其他程式和作業系統的其餘部分相容（甚至與不同的作業系統相容，如 Linux、Windows、macOS）。

  TF_AbstractOpSetOpType(fn_op, fn_name.c_str(), s);
  ASSERT_EQ(TF_OK, TF_GetCode(s)) << TF_Message(s);

  // Build two abstract input tensors as function arguments.
  std::vector<TF_AbstractTensor*> func_args;
  {
    TFE_Context* eager_ctx =
        TF_ExecutionContextGetTFEContext(eager_execution_ctx, status.get());
    ASSERT_EQ(TF_OK, TF_GetCode(status.get())) << TF_Message(status.get());

// 이제 환경 변수를 읽을 수 있습니다

Hello Wade Wilson from Python

// 이후에는 해당 환경 변수가 존재하지 않습니다
$ python main.py

Hello World from Python
```

</div>

/// tip | 팁

[The Twelve-Factor App: Config](https://12factor.net/config) 에서 좀 더 자세히 알아볼 수 있습니다.

///

## 타입과 검증 { #types-and-validation }

// 现在就可以读取到环境变量了

Hello Wade Wilson from Python

// 在此之后这个环境变量将不会依然存在
$ python main.py

Hello World from Python
```

</div>

/// tip | 提示

你可以在 [The Twelve-Factor App: 配置](https://12factor.net/config) 中了解更多信息。

///

## 类型和验证 { #types-and-validation }

这些环境变量只能处理**文本字符串**，因为它们是处于 Python 范畴之外的，必须与其他程序和操作系统的其余部分兼容（甚至与不同的操作系统兼容，如 Linux、Windows、macOS）。

          // requireNonNull is safe because right must exist in order to get a negative factor.
          requireNonNull(right);
          if (right.balanceFactor() > 0) {
            right = right.rotateRight();
          }
          return rotateLeft();
        case 2:
          // requireNonNull is safe because left must exist in order to get a positive factor.
          requireNonNull(left);
          if (left.balanceFactor() < 0) {

max_wait  (duration)  maximum wait time between operations, defaults to '15s'
cycle     (duration)  time duration between scanner cycles
```

Example: the following setting will decrease the scanner speed by a factor of 3, reducing the system resource use, but increasing the latency of updates being reflected.

```sh
~ mc admin config set alias/ scanner delay=30.0
```

    private final transient ConcurrentMap<E, Integer> countMap;

    /**
     * Creates a new, empty {@code OldConcurrentHashMultiset} using the default initial capacity,
     * load factor, and concurrency settings.
     */
    static <E> OldConcurrentHashMultiset<E> create() {
      return new OldConcurrentHashMultiset<E>(new ConcurrentHashMap<E, Integer>());
    }

    @VisibleForTesting