```

默认情况下，这个 `CORSMiddleware` 实现所使用的默认参数较为保守，所以你需要显式地启用特定的源、方法或者 headers，以便浏览器能够在跨域上下文中使用它们。

支持以下参数：

* `allow_origins` - 一个允许跨域请求的源列表。例如 `['https://example.org', 'https://www.example.org']`。你可以使用 `['*']` 允许任何源。
* `allow_origin_regex` - 一个正则表达式字符串，匹配的源允许跨域请求。例如 `'https://.*\.example\.org'`。
* `allow_methods` - 一个允许跨域请求的 HTTP 方法列表。默认为 `['GET']`。你可以使用 `['*']` 来允许所有标准方法。

        "username": "johndoe",
        "full_name": "John Doe",
        "email": "johndoe@example.com",
        "hashed_password": "$2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW",
        "disabled": False,
    },
    "alice": {
        "username": "alice",
        "full_name": "Alice Chains",
        "email": "alicechains@example.com",
        "hashed_password": "$2b$12$gSvqqUPvlXP2tfVFaWK1Be7DlH.PKZbv5H8KnzzVgXXbVxpva.pFm",

        "username": "johndoe",
        "full_name": "John Doe",
        "email": "johndoe@example.com",
        "hashed_password": "$2b$12$EixZaYVK1fsbw1ZfbX3OXePaWxn96p36WQoeG6Lruj3vjPGga31lW",
        "disabled": False,
    },
    "alice": {
        "username": "alice",
        "full_name": "Alice Chains",
        "email": "alicechains@example.com",
        "hashed_password": "$2b$12$gSvqqUPvlXP2tfVFaWK1Be7DlH.PKZbv5H8KnzzVgXXbVxpva.pFm",

Activating a virtual environment also changes a couple of other things, but this is one of the most important things it does.

## Checking a Virtual Environment

When you check if a virtual environment is active, for example with:

//// tab | Linux, macOS, Windows Bash

<div class="termy">

    return value < min ? min : value < max ? value : max;
  }

  /**
   * Returns the values from each provided array combined into a single array. For example, {@code
   * concat(new short[] {a, b}, new short[] {}, new short[] {c}} returns the array {@code {a, b,
   * c}}.
   *
   * @param arrays zero or more {@code short} arrays

    return value < min ? min : value < max ? value : max;
  }

  /**
   * Returns the values from each provided array combined into a single array. For example, {@code
   * concat(new short[] {a, b}, new short[] {}, new short[] {c}} returns the array {@code {a, b,
   * c}}.
   *
   * @param arrays zero or more {@code short} arrays

 * with {@link #where} and types are resolved using {@link #resolveType}.
 *
 * <p>Note that usually type mappings are already implied by the static type hierarchy (for example,
 * the {@code E} type variable declared by class {@code List} naturally maps to {@code String} in
 * the context of {@code class MyStringList implements List<String>}). In such case, prefer to use

# Query Parameters and String Validations

**FastAPI** allows you to declare additional information and validation for your parameters.

Let's take this application as example:

//// tab | Python 3.10+

```Python hl_lines="7"
{!> ../../docs_src/query_params_str_validations/tutorial001_py310.py!}
```

////

//// tab | Python 3.8+

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

Поскольку мы используем относительный URL, если ваш API расположен по адресу `https://example.com/`, то он будет ссылаться на `https://example.com/token`. Если же ваш API расположен по адресу `https://example.com/api/v1/`, то он будет ссылаться на `https://example.com/api/v1/token`.

  // must start and end with an alphanumeric character (e.g. 'MyName',  or 'my.name',  or
  // '123-abc', regex used for validation is '([A-Za-z0-9][-A-Za-z0-9_.]*)?[A-Za-z0-9]') with an
  // optional DNS subdomain prefix and '/' (e.g. 'example.com/MyName')
  //
  // Required.
  optional string name = 1;

  // Expression represents the expression which will be evaluated by CEL. Must evaluate to bool.