Estos validadores personalizados son para cosas que pueden comprobarse solo con los mismos datos provistos en el request.

///

### Entiende ese código { #understand-that-code }

El punto importante es solo usar `AfterValidator` con una función dentro de `Annotated`. Si quieres, sáltate esta parte. 🤸

---

                 * behavior is undefined because of the concurrent mutation.)
                 *
                 * (Our prototype checker happens to be "smart" enough to understand this for the
                 * *get* call in getValue but not for the *put* call here.)
                 *
                 * (Arguably we should use requireNonNull rather than uncheckedCastNullableTToT: We

## Ready to Work { #ready-to-work }

Now you're ready to start working on your project.



/// tip

Do you want to understand what's all that above?

Continue reading. 👇🤓

///

## Why Virtual Environments { #why-virtual-environments }

To work with FastAPI you need to install [Python](https://www.python.org/).

We will enable bucket event notification to trigger whenever a JPEG image is uploaded or deleted `images` bucket on `myminio` server. Here ARN value is `arn:minio:sqs::1:amqp`. To understand more about ARN please follow [AWS ARN](http://docs.aws.amazon.com/general/latest/gr/aws-arns-and-namespaces.html) documentation.

```
mc mb myminio/images
mc event add myminio/images arn:minio:sqs::1:amqp --suffix .jpg

mouse--a mouse--O mouse!'  The Mouse looked at her rather
inquisitively, and seemed to her to wink with one of its little
eyes, but it said nothing.

  `Perhaps it doesn't understand English,' thought Alice; `I
daresay it's a French mouse, come over with William the
Conqueror.'  (For, with all her knowledge of history, Alice had
no very clear notion how long ago anything had happened.)  So she

Check more details in the [Deployment](deployment/index.md) section.

///

## Benchmarks and speed { #benchmarks-and-speed }

To understand more about it, see the section [Benchmarks](https://fastapi.tiangolo.com/benchmarks/).

## Dependencies

FastAPI depends on Pydantic and Starlette.

### `standard` Dependencies

   * Integer#decode} and {@link Integer#toString()}. The returned converter throws {@link
   * NumberFormatException} if the input string is invalid.
   *
   * <p><b>Warning:</b> please see {@link Integer#decode} to understand exactly how strings are
   * parsed. For example, the string {@code "0123"} is treated as <i>octal</i> and converted to the
   * value {@code 83}.
   *
   * @since 16.0
   */

데이터베이스나 다른 API 같은 **외부 구성요소**와 통신이 필요한 어떤 종류의 검증이든 해야 한다면, 대신 **FastAPI Dependencies**를 사용해야 합니다. 이에 대해서는 나중에 배우게 됩니다.

이 커스텀 validator는 요청에서 제공된 **같은 데이터만**으로 확인할 수 있는 것들을 위한 것입니다.

///

### 코드 이해하기 { #understand-that-code }

중요한 부분은 **`Annotated` 안에서 함수와 함께 `AfterValidator`를 사용한다는 것**뿐입니다. 이 부분은 건너뛰셔도 됩니다. 🤸

---

하지만 이 특정 코드 예제가 궁금하고 계속 보고 싶다면, 추가 세부사항은 다음과 같습니다.

To understand more about it, see the section [Benchmarks](https://fastapi.tiangolo.com/benchmarks/).

## Dependencies { #dependencies }

FastAPI depends on Pydantic and Starlette.