# Handling Errors { #handling-errors }

There are many situations in which you need to notify an error to a client that is using your API.

This client could be a browser with a frontend, a code from someone else, an IoT device, etc.

You could need to tell the client that:

* The client doesn't have enough privileges for that operation.
* The client doesn't have access to that resource.
* The item the client was trying to access doesn't exist.
* etc.

### `RequestValidationError` vs `ValidationError`

/// warning | 警告

如果您觉得现在还用不到以下技术细节，可以先跳过下面的内容。

///

`RequestValidationError` 是 Pydantic 的 <a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a> 的子类。

**FastAPI** 调用的就是 `RequestValidationError` 类，因此，如果在 `response_model` 中使用 Pydantic 模型，且数据有错误时，在日志中就会看到这个错误。

# Manejo de Errores { #handling-errors }

Existen muchas situaciones en las que necesitas notificar un error a un cliente que está usando tu API.

Este cliente podría ser un navegador con un frontend, un código de otra persona, un dispositivo IoT, etc.

Podrías necesitar decirle al cliente que:

* El cliente no tiene suficientes privilegios para esa operación.
* El cliente no tiene acceso a ese recurso.
* El ítem al que el cliente intentaba acceder no existe.

* Decompressing gzip-compressed request bodies.
* Automatically logging all request bodies.

## Handling custom request body encodings { #handling-custom-request-body-encodings }

Let's see how to make use of a custom `Request` subclass to decompress gzip requests.

And an `APIRoute` subclass to use that custom request class.

// one of the comparison instructions that require special handling.
func IsARM64ADR(op obj.As) bool {
	switch op {
	case arm64.AADR, arm64.AADRP:
		return true
	}
	return false
}

// IsARM64CMP reports whether the op (as defined by an arm64.A* constant) is
// one of the comparison instructions that require special handling.
func IsARM64CMP(op obj.As) bool {
	switch op {

	tw := tar.NewWriter(&buf)
	var files = []struct {
		Name, Body string
	}{
		{"readme.txt", "This archive contains some text files."},
		{"gopher.txt", "Gopher names:\nGeorge\nGeoffrey\nGonzo"},
		{"todo.txt", "Get animal handling license."},
	}
	for _, file := range files {
		hdr := &tar.Header{
			Name: file.Name,
			Mode: 0600,
			Size: int64(len(file.Body)),
		}
		if err := tw.WriteHeader(hdr); err != nil {
			log.Fatal(err)

    validations:
      required: true

  - type: textarea
    id: error-handling-proposal
    attributes:
      label: Does this affect error handling?
      description: If so, how does this differ from previous error handling proposals?
      placeholder: |
       Yes or No

       If yes, 
        1.how does this differ from previous error handling proposals?

    validations:
      required: true

  - type: textarea

		return true
	}
	return false
}

// IsPPC64CMP reports whether the op (as defined by an ppc64.A* constant) is
// one of the CMP instructions that require special handling.
func IsPPC64CMP(op obj.As) bool {
	switch op {
	case ppc64.ACMP, ppc64.ACMPU, ppc64.ACMPW, ppc64.ACMPWU, ppc64.AFCMPO, ppc64.AFCMPU, ppc64.ADCMPO, ppc64.ADCMPU, ppc64.ADCMPOQ, ppc64.ADCMPUQ:
		return true
	}

* Распаковка тел запросов, сжатых с помощью gzip.
* Автоматическое логирование всех тел запросов.

## Обработка пользовательского кодирования тела запроса { #handling-custom-request-body-encodings }

Посмотрим как использовать пользовательский подкласс `Request` для распаковки gzip-запросов.

И подкласс `APIRoute`, чтобы использовать этот пользовательский класс запроса.

// one of the CMP instructions that require special handling.
func IsMIPSCMP(op obj.As) bool {
	switch op {
	case mips.ACMPEQF, mips.ACMPEQD, mips.ACMPGEF, mips.ACMPGED,
		mips.ACMPGTF, mips.ACMPGTD:
		return true
	}
	return false
}

// IsMIPSMUL reports whether the op (as defined by an mips.A* constant) is
// one of the MUL/DIV/REM/MADD/MSUB instructions that require special handling.
func IsMIPSMUL(op obj.As) bool {
	switch op {