You can achieve that using <a href="https://docs.pydantic.dev/latest/concepts/validators/#field-after-validator" class="external-link" target="_blank">Pydantic's `AfterValidator`</a> inside of `Annotated`.

/// tip

Pydantic also has <a href="https://docs.pydantic.dev/latest/concepts/validators/#field-before-validator" class="external-link" target="_blank">`BeforeValidator`</a> and others. 🤓

FastAPI uses Pydantic model's `.dict()` with <a href="https://docs.pydantic.dev/1.10/usage/exporting_models/#modeldict" class="external-link" target="_blank">its `exclude_unset` parameter</a> to achieve this.

///

/// info

You can also use:

* `response_model_exclude_defaults=True`
* `response_model_exclude_none=True`

///

/// info | Informação

Você também pode usar:

* `response_model_exclude_defaults=True`
* `response_model_exclude_none=True`

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[66:73] hl[71] *}

### Executar o App

Você pode executar o app:

<div class="termy">

```console
$ fastapi dev main.py

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

pkg syscall (freebsd-386), type Dirent struct, Fileno uint32
pkg syscall (freebsd-386), type Dirent struct, Namlen uint8
pkg syscall (freebsd-386), type Stat_t struct, Blksize uint32
pkg syscall (freebsd-386), type Stat_t struct, Dev uint32
pkg syscall (freebsd-386), type Stat_t struct, Gen uint32
pkg syscall (freebsd-386), type Stat_t struct, Ino uint32
pkg syscall (freebsd-386), type Stat_t struct, Lspare int32

force_reload() {
    restart
}

rh_status() {
    # run checks to determine if the service is running or use generic status
    status -p $pidfile $prog
}

rh_status_q() {
    rh_status >/dev/null 2>&1
}


case "$1" in
    start)
        rh_status_q && exit 0
        $1
        ;;
    stop)
        rh_status_q || exit 0
        $1
        ;;
    restart)
        $1

### Check the automatic API docs { #check-the-automatic-api-docs }

Now, run the `fastapi` command with your file:

<div class="termy">

```console
$ fastapi dev main.py

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

</div>

          </offlineLinks>
          <links>
            <link>https://docs.oracle.com/en/java/javase/21/docs/api/</link>
            <link>https://errorprone.info/api/latest/</link>
            <link>https://jspecify.dev/docs/api/</link>
          </links>
          <overview>../overview.html</overview>
        </configuration>
      </plugin>
      <plugin>
        <artifactId>maven-resources-plugin</artifactId>

이 과정을 통해 코드 중복을 최소화하고, 모든 곳에서 자동 완성, 타입 검사, 에러 확인 기능이 제공되는 최적의 방식을 찾아냈습니다.

이 모든 것은 개발자들에게 최고의 개발 경험을 제공하기 위해 설계되었습니다.

---

## 필요조건

여러 대안을 테스트한 후, [Pydantic](https://docs.pydantic.dev/)을 사용하기로 결정했습니다.

이후 저는 **Pydantic**이 JSON Schema와 완벽히 호환되도록 개선하고, 다양한 제약 조건 선언을 지원하며, 여러 편집기에서의 자동 완성과 타입 검사 기능을 향상하기 위해 기여했습니다.

또한, 또 다른 주요 필요조건이었던 [Starlette](https://www.starlette.io/)에도 기여했습니다.

---

## 개발

Aqui estão várias formas de se fazer isso.

## `schema_extra` do Pydantic

Você pode declarar um `example` para um modelo Pydantic usando `Config` e `schema_extra`, conforme descrito em <a href="https://docs.pydantic.dev/latest/concepts/json_schema/#schema-customization" class="external-link" target="_blank">Documentação do Pydantic: Schema customization</a>:

{* ../../docs_src/schema_extra_example/tutorial001.py hl[15:23] *}