This could be especially useful during testing, as it's very easy to override a dependency with your own custom settings.

### The config file { #the-config-file }

Coming from the previous example, your `config.py` file could look like:

{* ../../docs_src/settings/app02_an_py39/config.py hl[10] *}

func newMinioCollector() *minioCollector {
	return &minioCollector{
		desc: prometheus.NewDesc("minio_stats", "Statistics exposed by MinIO server", nil, nil),
	}
}

// minioCollector is the Custom Collector
type minioCollector struct {
	desc *prometheus.Desc
}

// Describe sends the super-set of all possible descriptors of metrics
func (c *minioCollector) Describe(ch chan<- *prometheus.Desc) {
	ch <- c.desc

}

// URI scheme constants.
const (
	httpScheme  = "http"
	httpsScheme = "https"
)

// nopCharsetConverter is a dummy charset convert which just copies input to output,
// it is used to ignore custom encoding charset in S3 XML body.
func nopCharsetConverter(label string, input io.Reader) (io.Reader, error) {
	return input, nil
}

// xmlDecoder provide decoded value in xml.

{* ../../docs_src/query_params_str_validations/tutorial014_an_py310.py hl[10] *}

## Benutzerdefinierte Validierung { #custom-validation }

Es kann Fälle geben, in denen Sie eine **benutzerdefinierte Validierung** durchführen müssen, die nicht mit den oben gezeigten Parametern durchgeführt werden kann.

But you can also provide other alternative `servers`, for example if you want *the same* docs UI to interact with both a staging and a production environment.

If you pass a custom list of `servers` and there's a `root_path` (because your API lives behind a proxy), **FastAPI** will insert a "server" with this `root_path` at the beginning of the list.

For example:

{* ../../docs_src/query_params_str_validations/tutorial014_an_py310.py hl[10] *}

## Validação personalizada { #custom-validation }

Podem existir casos em que você precise fazer alguma **validação personalizada** que não pode ser feita com os parâmetros mostrados acima.

		// the client. So, logger and Error response XML were not using this
		// value. This is set here so that this header can be logged as
		// part of the log entry, Error response XML and auditing.
		// Set custom headers such as x-amz-request-id for each request.
		w.Header().Set(xhttp.AmzRequestID, mustGetRequestID(UTCNow()))
		if globalLocalNodeName != "" {
			w.Header().Set(xhttp.AmzRequestHostID, globalLocalNodeNameHex)
		}

    /**
     * Returns the path to the pom file for this project.
     * A project is usually read from a file named {@code pom.xml},
     * which contains the {@linkplain #getModel() model} in an XML form.
     * When a custom {@code org.apache.maven.api.spi.ModelParser} is used,
     * the path may point to a non XML file.
     * <p>
     * The POM path is also used to define the {@linkplain #getBasedir() base directory}
     * of the project.

		return nil, config.ErrInvalidNumberOfErasureEndpoints(nil).Msg(msg)
	}

	var setSize uint64
	// Custom set drive count allows to override automatic distribution.
	// only meant if you want to further optimize drive distribution.
	if setDriveCount > 0 {

{* ../../docs_src/dependencies/tutorial008b_an_py39.py hl[18:22,31] *}

Si quieres capturar excepciones y crear un response personalizado en base a eso, crea un [Manejador de Excepciones Personalizado](../handling-errors.md#install-custom-exception-handlers){.internal-link target=_blank}.

## Dependencias con `yield` y `except` { #dependencies-with-yield-and-except }