<div class="screenshot">
<img src="/img/tutorial/header-param-models/image01.png">
</div>

## Prohibir Headers Extra { #forbid-extra-headers }

En algunos casos de uso especiales (probablemente no muy comunes), podrías querer **restringir** los headers que deseas recibir.

Puedes usar la configuración del modelo de Pydantic para `prohibir` cualquier campo `extra`:

	{err: errObjectTampered, errCode: ErrObjectTampered},

	{err: nil, errCode: ErrNone},
	{err: errors.New("Custom error"), errCode: ErrInternalError}, // Case where err type is unknown.
}

func TestAPIErrCode(t *testing.T) {
	ctx := t.Context()
	for i, testCase := range toAPIErrorTests {
		errCode := toAPIErrorCode(ctx, testCase.err)
		if errCode != testCase.errCode {

)

var errEtcdUnreachable = errors.New("etcd is unreachable, please check your endpoints")

func etcdErrToErr(err error, etcdEndpoints []string) error {
	if err == nil {
		return nil
	}
	switch err {
	case context.DeadlineExceeded:
		return fmt.Errorf("%w %s", errEtcdUnreachable, etcdEndpoints)
	default:
		return fmt.Errorf("unexpected error %w from etcd, please check your endpoints %s", err, etcdEndpoints)
	}
}

        switch (form.crudMode) {
        case CrudMode.CREATE:
            return OptionalEntity.of(new RelatedContent()).map(entity -> {
                entity.setCreatedBy(username);
                entity.setCreatedTime(currentTime);
                return entity;
            });
        case CrudMode.EDIT:
            if (form instanceof EditForm) {

In this case, you could want to document how that external API *should* look like. What *path operation* it should have, what body it should expect, what response it should return, etc.

## An app with callbacks { #an-app-with-callbacks }

NOTE:

- `timeToFirstByte` and `timeToResponse` will be expressed in Nanoseconds.
- Additionally in the case of the erasure coded setup `tags.objectLocation` provides per object details about
  - Pool number the object operation was performed on.
  - Set number the object operation was performed on.

						globalMinioDefaultRegion, serviceS3), "policy"),
				},
				"Policy": []string{"policy"},
			},
			expected: ErrNone,
		},
	}

	// Run each test case individually.
	for i, testCase := range testCases {
		_, code := doesPolicySignatureMatch(testCase.form)
		if code != testCase.expected {

        switch (form.crudMode) {
        case CrudMode.CREATE:
            return OptionalEntity.of(new AccessToken()).map(entity -> {
                entity.setCreatedBy(username);
                entity.setCreatedTime(currentTime);
                return entity;
            });
        case CrudMode.EDIT:
            if (form instanceof EditForm) {

     */
    @Override
    public InputLocation getLocation(Object key) {
        if (key instanceof String string) {
            switch (string) {
                case "": {
                    return this.location;
                }
                default: {
                    return getOtherLocation(key);
                }
            }
        } else {

	if err != nil {
		t.Fatalf("%s.  Unable to get IP addresses of this host.", err)
	}

	for _, addr := range addrs {
		var ip net.IP
		switch v := addr.(type) {
		case *net.IPNet:
			ip = v.IP
		case *net.IPAddr:
			ip = v.IP
		}

		if ip.To4() != nil {
			localIP4.Add(ip.String())
		}
	}

	// Filter ipList by IPs those do not start with '127.'.