```Python
q: Union[str, None] = None
```

Ou bien, en Python 3.10 et supérieur :

```Python
q: str | None = None
```

Par exemple :

//// tab | Python 3.10+

```Python hl_lines="27"
{!> ../../docs_src/body_multiple_params/tutorial004_an_py310.py!}
```

## Use `StaticFiles`

* Import `StaticFiles`.
* "Mount" a `StaticFiles()` instance in a specific path.

{* ../../docs_src/static_files/tutorial001.py hl[2,6] *}

/// note | "Technical Details"

You could also use `from starlette.staticfiles import StaticFiles`.

```

由于我们必须用 `Query(default=None)` 替换默认值 `None`，`Query` 的第一个参数同样也是用于定义默认值。

所以：

```Python
q: Union[str, None] = Query(default=None)
```

...使得参数可选，等同于：

```Python
q: str = None
```

但是 `Query` 显式地将其声明为查询参数。

然后，我们可以将更多的参数传递给 `Query`。在本例中，适用于字符串的 `max_length` 参数：

```Python
q: Union[str, None] = Query(default=None, max_length=50)
```

  @After
  public void validateUndirectedEdges() {
    for (Integer node : graph.nodes()) {
      new EqualsTester()
          .addEqualityGroup(
              graph.predecessors(node), graph.successors(node), graph.adjacentNodes(node))
          .testEquals();
    }
  }

  @Override
  @Test
  public void nodes_checkReturnedSetMutability() {

    call: Call,
    byteCount: Long,
  ) {
  }

  /**
   * Invoked when a request fails to be written.
   *
   * This method is invoked after [requestHeadersStart] or [requestBodyStart]. Note that request
   * failures do not necessarily fail the entire call.
   */
  open fun requestFailed(
    call: Call,
    ioe: IOException,
  ) {
  }

  /**

import java.io.File;

import org.apache.maven.toolchain.model.PersistedToolchains;

/**
 * Builds the toolchains model from a previously configured filesystem path to the toolchains file.
 * <strong>Note:</strong> This is an internal component whose interface can change without prior notice.
 *
 * @deprecated use {@link org.apache.maven.toolchain.building.ToolchainsBuilder} instead
 */
@Deprecated

   * Unicode 6.0. Note that this is a stronger criterion than simply whether the bytes can be
   * decoded. For example, some versions of the JDK decoder will accept "non-shortest form" byte
   * sequences, but encoding never reproduces these. Such byte sequences are <i>not</i> considered
   * well-formed.
   *

/**
 * Relocation source from standard distribution management. This is the "one and only" relocation implementation that
 * existed in Maven 3 land, uses POM distributionManagement/relocation.
 * <p>
 * Note: this component should kick-in last regarding relocations.
 *
 * @since 4.0.0
 * @deprecated since 4.0.0, use {@code maven-api-impl} jar instead
 */
@Singleton
@Named(DistributionManagementArtifactRelocationSource.NAME)

```

## `Cookie`のパラメータを宣言

次に、`Path`や`Query`と同じ構造を使ってクッキーのパラメータを宣言します。

最初の値がデフォルト値で、追加の検証パラメータや注釈パラメータをすべて渡すことができます:

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

/// note | "技術詳細"

`Cookie`は`Path`と`Query`の「姉妹」クラスです。また、同じ共通の`Param`クラスを継承しています。

しかし、`fastapi`から`Query`や`Path`、`Cookie`などをインポートする場合、それらは実際には特殊なクラスを返す関数であることを覚えておいてください。

///

/// info | "情報"

So, you will have to make sure your data is of the correct type. E.g. it is compatible with JSON, if you are returning a `JSONResponse`.

And also that you are not sending any data that should have been filtered by a `response_model`.

///

### More info

/// note | "Technical Details"

You could also use `from starlette.responses import Response` or `from starlette.responses import JSONResponse`.