# 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`と`ValidationError`

/// warning | 注意

これらは今のあなたにとって重要でない場合は省略しても良い技術的な詳細です。

///

`RequestValidationError`はPydanticの<a href="https://docs.pydantic.dev/latest/concepts/models/#error-handling" class="external-link" target="_blank">`ValidationError`</a>のサブクラスです。

**FastAPI** は`response_model`でPydanticモデルを使用していて、データにエラーがあった場合、ログにエラーが表示されるようにこれを使用しています。

 *
 * @author higa
 */
public abstract class PropertiesUtil {

    /**
     * Do not instantiate.
     */
    protected PropertiesUtil() {
    }

    /**
     * Wraps exception handling for {@link Properties#load(InputStream)}.
     * <p>
     * The input stream is not closed.
     * </p>
     *
     * @param props the property set (must not be {@literal null})

- **I/O Operations** (`org.codelibs.core.io`) - File handling, resource management, stream utilities, and traversal utilities for efficient resource processing
- **Reflection** (`org.codelibs.core.lang`) - Class loading, method/field access, type introspection utilities, and generics support
- **Exception Handling** (`org.codelibs.core.exception`) - Runtime exception wrappers for common checked exceptions with consistent error handling

### Modern Java 21 Support

* 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.

- [ ] Implement lease break notification handling
- [ ] Modify SmbFile to support lease-based caching
- [ ] Add lease upgrade/downgrade logic
- [ ] Implement lease epoch tracking for v2 leases

#### 1.3 Integration Points
- Modify `Smb2CreateRequest` to include lease contexts
- Update `SmbFile` caching logic to use leases
- Add lease break handling in `SmbTransport`

---

### Phase 2: Persistent Handles

import org.lastaflute.web.response.StreamResponse;

import jakarta.annotation.Resource;

/**
 * Action class for handling document redirection requests.
 * This action processes "go" requests that redirect users to specific documents
 * while tracking click events and handling various URL types including file system paths.
 */
public class GoAction extends FessSearchAction {

    /**

import org.codelibs.core.exception.NoSuchAlgorithmRuntimeException;

/**
 * Utility for handling {@link MessageDigest}.
 *
 * @author higa
 * @author shinsuke
 */
public abstract class MessageDigestUtil {

    /**
     * Do not instantiate.
     */
    protected MessageDigestUtil() {
    }

    /**
     * Wraps the exception handling of {@link MessageDigest#getInstance(String)}.
     *
     * @param algorithm

    /** The time manager for handling time-related operations. */
    @Resource
    private TimeManager timeManager;

    /** The async manager for handling asynchronous operations. */
    @Resource
    private AsyncManager asyncManager;

    /** The session manager for handling user sessions. */
    @Resource
    private SessionManager sessionManager;

    @Resource
    protected ActivityHelper activityHelper;

    /** Manager for handling HTTP response operations. */
    @Resource
    protected ResponseManager responseManager;

    /** Time manager for handling date and time operations. */
    @Resource
    protected TimeManager timeManager;

    /** System helper for various system-level operations. */
    @Resource