...but continue reading below to see how to overcome that.

## Return Type and Data Filtering { #return-type-and-data-filtering }

Let's continue from the previous example. We wanted to **annotate the function with one type**, but we wanted to be able to return from the function something that actually includes **more data**.

									<filtering>true</filtering>
									<includes>
										<include>**/*</include>
									</includes>
									<excludes>
										<exclude>packaging.properties</exclude>
									</excludes>
								</resource>
								<resource>
									<directory>src/packaging/deb/</directory>
									<filtering>true</filtering>
									<includes>
										<include>**/*</include>

- **Extensible Architecture**: Plugin system for custom extractors, transformers, and clients
- **Rate Limiting**: Politeness policies and interval controllers
- **URL Filtering**: Regex-based inclusion/exclusion patterns
- **Data Persistence**: Multiple backend options including OpenSearch integration

## Technology Stack

- **Java**: 21+ (requires Java 21 or higher)

    protected final AtomicBoolean forceStop = new AtomicBoolean(false);

    /** A cache for language items. */
    protected LoadingCache<String, List<Map<String, String>>> langItemsCache;

    /** The encoding for filtering paths. */
    protected String filterPathEncoding;

    /** An array of supported language codes. */
    protected String[] supportedLanguages;

947 title: 'Mastering Soft Delete: Advanced SQLAlchemy Techniques' - author: Shubhendra Kushwaha author_link: https://www.linkedin.com/in/theshubhendra/ link: https://theshubhendra.medium.com/role-based-row-filtering-advanced-sqlalchemy-techniques-733e6b1328f6 title: 'Role based row filtering: Advanced SQLAlchemy Techniques' German: - author: Marcel Sander (actidoo) author_link: https://www.actidoo.com link: https://www.actidoo.com/de/blog/python-fastapi-domain-driven-design title: Domain-driven...

 *
 * Features:
 * - Directory traversal prevention
 * - Path normalization
 * - Blacklist/whitelist support
 * - UNC path validation
 * - Special character filtering
 * - Length validation
 */
public class PathValidator {

    private static final Logger log = LoggerFactory.getLogger(PathValidator.class);

    // Path traversal patterns

	FastGetObjInfo bool // Only for S3 Head/Get Object calls for now
	NoAuditLog     bool // Only set for decom, rebalance, to avoid double audits.
}

// WalkOptions provides filtering, marker and other Walk() specific options.
type WalkOptions struct {
	Filter       func(info FileInfo) bool // return WalkFilter returns 'true/false'
	Marker       string                   // set to skip until this object

    ]
```

FastAPI will use the return type annotation to perform:

* Data validation
* Automatic documentation
    * It could power automatic client generators
* **Data filtering**

Before this version it was only supported via the `response_model` parameter.

Read more about it in the new docs: [Response Model - Return Type](https://fastapi.tiangolo.com/tutorial/response-model/).