# Body – Felder { #body-fields }

So wie Sie zusätzliche Validierung und Metadaten in Parametern der *Pfadoperation-Funktion* mittels `Query`, `Path` und `Body` deklarieren, können Sie auch innerhalb von Pydantic-Modellen zusätzliche Validierung und Metadaten deklarieren, mittels Pydantics `Field`.

## `Field` importieren { #import-field }

Importieren Sie es zuerst:

{* ../../docs_src/body_fields/tutorial001_an_py310.py hl[4] *}

/// warning | Achtung

import org.apache.maven.artifact.versioning.DefaultArtifactVersion;
import org.apache.maven.repository.legacy.metadata.ArtifactMetadataSource;
import org.apache.maven.repository.legacy.metadata.MetadataResolutionRequest;
import org.apache.maven.repository.legacy.metadata.ResolutionGroup;

@Named("classpath")
@Singleton
@Deprecated
public class SimpleArtifactMetadataSource implements ArtifactMetadataSource {

        }
    }

    /**
     * SSO metadata endpoint.
     *
     * This method handles requests for SSO metadata, typically used by SAML or
     * other SSO protocols that require metadata exchange. The actual metadata
     * content is generated by the configured SSO authenticator.
     *
     * @return ActionResponse containing the SSO metadata or error page
     */
    @Execute

h3. Plugins

* Execution model
* Metadata model
* Metadata tooling
 ** Metadata extractor
 ** Metadata reader
 ** Metadata writer
 ** Metadata adapter (if required for the target system)
* Maven packaging and lifecycle
* Maven test harness for plugin execution model
* Eclipse IDE tooling for plugin execution model and metadata model

- we also seem to have information like the plugin lifecycle model that's buried inside the maven execution model

import org.apache.maven.artifact.repository.ArtifactRepository;
import org.apache.maven.artifact.repository.RepositoryRequest;
import org.apache.maven.artifact.repository.metadata.RepositoryMetadataResolutionException;
import org.apache.maven.artifact.repository.metadata.Versioning;
import org.apache.maven.artifact.resolver.ArtifactNotFoundException;
import org.apache.maven.artifact.resolver.ArtifactResolutionException;

/**

package org.apache.maven.artifact.repository.metadata;

import org.apache.maven.artifact.Artifact;
import org.apache.maven.artifact.ArtifactUtils;
import org.apache.maven.artifact.repository.ArtifactRepository;
import org.apache.maven.artifact.versioning.ArtifactVersion;
import org.apache.maven.artifact.versioning.Restriction;
import org.apache.maven.artifact.versioning.VersionRange;

/**
 * Metadata for the artifact directory of the repository.

	"encoding/binary"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"time"

	"github.com/cespare/xxhash/v2"
	jsoniter "github.com/json-iterator/go"
)

// XL constants.
const (
	// XL metadata file carries per object metadata.
	xlStorageFormatFileV1 = "xl.json"
)

// Valid - tells us if the format is sane by validating
// format version and erasure coding information.
func (m *xlMetaV1Object) valid() bool {

 * This enum is used to differentiate between various SSO operations,
 * such as metadata requests and logout actions.
 */
public enum SsoResponseType {
    /**
     * Indicates a request for SSO metadata, which is typically used for
     * configuration and discovery in protocols like SAML.
     */
    METADATA,

    /**
     * Indicates a request to perform a logout operation, terminating the

 * under the License.
 */
package org.apache.maven.artifact.metadata;

import org.apache.maven.artifact.Artifact;

/**
 * AbstractArtifactMetadata
 */
@Deprecated
public abstract class AbstractArtifactMetadata
        extends org.apache.maven.repository.legacy.metadata.AbstractArtifactMetadata
        implements org.apache.maven.artifact.metadata.ArtifactMetadata {
    protected AbstractArtifactMetadata(Artifact artifact) {

// from the metadata using the SSE-Copy client key of the HTTP headers
// and returns the decrypted object key.
func (sse ssecCopy) UnsealObjectKey(h http.Header, metadata map[string]string, bucket, object string) (key ObjectKey, err error) {
	clientKey, err := sse.ParseHTTP(h)
	if err != nil {
		return key, err
	}
	return unsealObjectKey(clientKey[:], metadata, bucket, object)
}