*
 * <p>Advantages compared to {@code long[]}:
 *
 * <ul>
 *   <li>All the many well-known advantages of immutability (read <i>Effective Java</i>, third
 *       edition, Item 17).
 *   <li>Has the value-based (not identity-based) {@link #equals}, {@link #hashCode}, and {@link
 *       #toString} behavior you expect.

///

The end result is that the item paths are now:

* `/items/`
* `/items/{item_id}`

...as we intended.

* They will be marked with a list of tags that contain a single string `"items"`.

 *
 * <p>Advantages compared to {@code int[]}:
 *
 * <ul>
 *   <li>All the many well-known advantages of immutability (read <i>Effective Java</i>, third
 *       edition, Item 17).
 *   <li>Has the value-based (not identity-based) {@link #equals}, {@link #hashCode}, and {@link
 *       #toString} behavior you expect.

<img src="/img/python-types/image05.png">

Sans types, c'est presque impossible à réaliser.

Vous remarquerez que la variable `item` n'est qu'un des éléments de la list `items`.

Et pourtant, l'éditeur sait qu'elle est de type `str` et pourra donc vous aider à l'utiliser.

#### `Tuple` et `Set`

```

////

/// note

注意，`response_model`是「装饰器」方法（`get`，`post` 等）的一个参数。不像之前的所有参数和请求体，它不属于*路径操作函数*。

///

它接收的类型与你将为 Pydantic 模型属性所声明的类型相同，因此它可以是一个 Pydantic 模型，但也可以是一个由 Pydantic 模型组成的 `list`，例如 `List[Item]`。

FastAPI 将使用此 `response_model` 来：

* 将输出数据转换为其声明的类型。
* 校验数据。
* 在 OpenAPI 的*路径操作*中为响应添加一个 JSON Schema。
* 并在自动生成文档系统中使用。

但最重要的是：

* 会将输出数据限制在该模型定义内。下面我们会看到这一点有多重要。

/// note | "技术细节"

                        </h1>
                    </div>
                    <div class="col-sm-6">
                        <ol class="breadcrumb float-sm-right">
                            <li class="breadcrumb-item active"><la:link href="/admin/searchlist/search?q=${f:u(q)}">
                                <la:message key="labels.search_list_configuration"/>
                            </la:link></li>
                        </ol>

### Validación

* Validación para la mayoría (¿o todos?) los **tipos de datos** de Python incluyendo:
    * Objetos JSON (`dict`).
    * JSON array (`list`) definiendo tipos de ítem.
    * Campos de texto (`str`) definiendo longitudes mínimas y máximas.
    * Números (`int`, `float`) con valores mínimos y máximos, etc.

* Validación para tipos más exóticos como:
    * URL.
    * Email.

Isso ocorre por que, por padrão, o FastAPI irá verificar cada item dentro do dicionário e garantir que ele seja serializável para JSON, utilizando o mesmo[Codificador Compatível com JSON](../tutorial/encoder.md){.internal-link target=_blank} explicado no tutorial. Isso permite que você retorne **objetos abstratos**, como modelos do banco de dados, por exemplo.

// or a string representing a sub-field or item. The string will follow one of these four formats:
// 'f:<name>', where <name> is the name of a field in a struct, or key in a map
// 'v:<value>', where <value> is the exact json formatted value of a list item
// 'i:<index>', where <index> is position of a item in a list
// 'k:<keys>', where <keys> is a map of  a list item's key fields to their unique values

      private var canRemove = false

      override fun hasNext(): Boolean {
        if (nextUrl != null) return true

        canRemove = false // Prevent delegate.remove() on the wrong item!
        while (delegate.hasNext()) {
          try {
            delegate.next().use { snapshot ->
              val metadata = snapshot.getSource(ENTRY_METADATA).buffer()