* **Soporte en el editor**.
* **Type checks**.

...y **FastAPI** usa las mismas declaraciones para:

* **Definir requerimientos**: desde request path parameters, query parameters, headers, bodies, dependencies, etc.
* **Convertir datos**: desde el request al tipo requerido.
* **Validar datos**: viniendo de cada request:

    val encodedPathSegments: List<String> = httpUrl.encodedPathSegments
    val pathSegments: List<String> = httpUrl.pathSegments
    val encodedQuery: String? = httpUrl.encodedQuery
    val query: String? = httpUrl.query
    val querySize: Int = httpUrl.querySize
    val queryParameter: String? = httpUrl.queryParameter("")
    val queryParameterNames: Set<String> = httpUrl.queryParameterNames

};\n\n    // init state\n    this.state = {\n      isDestroyed: false,\n      isCreated: false,\n      scrollParents: [],\n    };\n\n    // get reference and popper elements (allow jQuery wrappers)\n    this.reference = reference && reference.jquery ? reference[0] : reference;\n    this.popper = popper && popper.jquery ? popper[0] : popper;\n\n    // Deep merge modifiers options\n    this.options.modifiers = {};\n    Object.keys({\n      ...Popper.Defaults.modifiers,\n      ...options.modifiers,\n...

## 定义 `File` 参数

创建文件（`File`）参数的方式与 `Body` 和 `Form` 一样：

```Python hl_lines="7"
{!../../docs_src/request_files/tutorial001.py!}
```

/// info | "说明"

`File` 是直接继承自 `Form` 的类。

注意，从 `fastapi` 导入的 `Query`、`Path`、`File` 等项，实际上是返回特定类的函数。

///

/// tip | "提示"

声明文件体必须使用 `File`，否则，FastAPI 会把该参数当作查询参数或请求体（JSON）参数。

///

文件作为「表单数据」上传。

如果把*路径操作函数*参数的类型声明为 `bytes`，**FastAPI** 将以 `bytes` 形式读取和接收文件内容。

{!> ../../docs_src/request_files/tutorial001.py!}
```

////

/// info | "Дополнительная информация"

`File` - это класс, который наследуется непосредственно от `Form`.

Но помните, что когда вы импортируете `Query`, `Path`, `File` и другие из `fastapi`, на самом деле это функции, которые возвращают специальные классы.

///

/// tip | "Подсказка"

	// Find
	var user2 User
	DB.Find(&user2, "id = ?", user.ID)
	pointerOfUser := &user2
	if err := DB.Model(&pointerOfUser).Association("Company").Find(&user2.Company); err != nil {
		t.Errorf("failed to query users, got error %#v", err)
	}
	user2.Manager = &User{}
	DB.Model(&user2).Association("Manager").Find(user2.Manager)
	CheckUser(t, user2, user)

	// Count
	AssertAssociationCount(t, user, "Company", 1, "")

   * unprivileged user may return a resource accessible only to a privileged user making a similar
   * call. To prevent this problem, create a key object that includes all values that affect the
   * result of the query. Or use {@code LoadingCache.get(K)}, which lacks the ability to refer to
   * state other than that in the key.
   *
   * <p><b>Warning:</b> as with {@link CacheLoader#load}, {@code loader} <b>must not</b> return

</p>
<p align="center">
    FastAPI 프레임워크, 고성능, 간편한 학습, 빠른 코드 작성, 준비된 프로덕션
</p>
<p align="center">
<a href="https://github.com/fastapi/fastapi/actions?query=workflow%3ATest" target="_blank">
    <img src="https://github.com/fastapi/fastapi/workflows/Test/badge.svg" alt="Test">
</a>
<a href="https://codecov.io/gh/fastapi/fastapi" target="_blank">

			<form action="<%=request.getContextPath()%>/admin/searchlist/search" method="GET" class="form-inline mt-2 sidebar-search">
				<div class="input-group">
					<input class="form-control form-control-sidebar" name="q" id="query"
						   maxlength="1000"
						   placeholder="<la:message key="labels.sidebar.placeholder_search" />">
					<div class="input-group-append">
						<button class="btn btn-sidebar" type="submit" name="search" id="search-btn">

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>

Isso significa que ele **sempre terá um valor**, só que às vezes o valor pode ser `None` (ou `null` em termos de JSON).

Isso quer dizer que, os clientes que usam sua API não precisam verificar se o valor existe ou não, eles podem **assumir que o campo sempre estará lá**, mas que em alguns casos terá o valor padrão de `None`.