{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[4] *}


/// warning | 注意

`Field`は他の全てのもの（`Query`、`Path`、`Body`など）とは違い、`fastapi`からではなく、`pydantic`から直接インポートされていることに注意してください。

///

## モデルの属性の宣言 { #declare-model-attributes }

以下のように`Field`をモデルの属性として使用することができます:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[11:14] *}

`Field`は`Query`や`Path`、`Body`と同じように動作し、全く同様のパラメータなどを持ちます。

/// note | 技術詳細

In this case, the list would have to include `http://localhost:8080` for the `:8080`-frontend to work correctly.

## Wildcards { #wildcards }

It's also possible to declare the list as `"*"` (a "wildcard") to say that all are allowed.

# Using Dataclasses { #using-dataclasses }

FastAPI is built on top of **Pydantic**, and I have been showing you how to use Pydantic models to declare requests and responses.

But FastAPI also supports using [`dataclasses`](https://docs.python.org/3/library/dataclasses.html) the same way:

{* ../../docs_src/dataclasses_/tutorial001_py310.py hl[1,6:11,18:19] *}

헤더 매개변수를 `Query`, `Path` 그리고 `Cookie` 매개변수들과 같은 방식으로 정의할 수 있습니다.

## `Header` 임포트 { #import-header }

먼저 `Header`를 임포트합니다:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[3] *}

## `Header` 매개변수 선언 { #declare-header-parameters }

`Path`, `Query` 그리고 `Cookie`를 사용한 동일한 구조를 이용하여 헤더 매개변수를 선언합니다.

첫 번째 값은 기본값이며, 추가 검증이나 어노테이션 매개변수 모두 전달할 수 있습니다:

{* ../../docs_src/header_params/tutorial001_an_py310.py hl[9] *}

        assertEquals(boolean.class, m1.getReturnType());
        assertEquals(0, m1.getParameterCount());
        assertEquals(0, m1.getExceptionTypes().length);

        // overlaps(SmbResourceLocator): boolean, declares CIFSException
        Method m2 = clazz.getMethod("overlaps", SmbResourceLocator.class);
        assertEquals(boolean.class, m2.getReturnType());
        assertEquals(1, m2.getParameterCount());

`Annotated` kullanmadan önce mutlaka FastAPI sürümünü en az 0.95.1 olacak şekilde [FastAPI sürümünü yükseltin](../deployment/versions.md#upgrading-the-fastapi-versions).

///

## Metadata Tanımlayın { #declare-metadata }

`Query` için geçerli olan parametrelerin aynısını tanımlayabilirsiniz.

Örneğin, `item_id` path parametresi için bir `title` metadata değeri tanımlamak isterseniz şunu yazabilirsiniz:

  echo 'If you have not, you will see a lot of undefined variable errors.'
else
  FROM_ENV=$(mktemp)
  # "export -p" prints a list of environment values in a safe-to-source format,
  # e.g. `declare -x TFCI_BAZEL_COMMON_ARGS="list of args"` for bash.
  export -p | grep TFCI > "$FROM_ENV"

  # Source the default ci values
  source ./ci/official/envs/ci_default

  # TODO(angerson) write this documentation

Todas las dependencias que hemos visto son una función o clase fija.

Pero podría haber casos en los que quieras poder establecer parámetros en la dependencia, sin tener que declarar muchas funciones o clases diferentes.

Imaginemos que queremos tener una dependencia que revise si el parámetro de query `q` contiene algún contenido fijo.

Pero queremos poder parametrizar ese contenido fijo.

Use base64 apenas se realmente precisar incluir dados binários em JSON e não puder usar arquivos para isso.

## Pydantic `bytes` { #pydantic-bytes }

Você pode declarar um modelo Pydantic com campos `bytes` e então usar `val_json_bytes` na configuração do modelo para indicar que deve usar base64 para *validar* os dados JSON de entrada; como parte dessa validação, ele decodificará a string base64 em bytes.

   * probably work around it by changing how we annotate the J2CL EnumMap, but that's probably more
   * trouble than just using Object.class.)
   *
   * Then we declare the getters for these fields as @GwtIncompatible so that no one can try to use
   * them under J2CL—or, as an unfortunate side effect, under GWT. We do still give the fields