## Official Guide { #official-guide }

Pydantic has an official <a href="https://docs.pydantic.dev/latest/migration/" class="external-link" target="_blank">Migration Guide</a> from v1 to v2.

It also includes what has changed, how validations are now more correct and strict, possible caveats, etc.

You can read it to understand better what has changed.

**FastAPI CLI** 是一個命令列程式，能用來運行你的 FastAPI 應用程式、管理你的 FastAPI 專案等。

當你安裝 FastAPI（例如使用 `pip install "fastapi[standard]"`），它會包含一個叫做 `fastapi-cli` 的套件，這個套件提供了 `fastapi` 命令。

要運行你的 FastAPI 應用程式來進行開發，你可以使用 `fastapi dev` 命令：

<div class="termy">

```console
$ <font color="#4E9A06">fastapi</font> dev <u style="text-decoration-style:single">main.py</u>
<font color="#3465A4">INFO    </font> Using path <font color="#3465A4">main.py</font>

/// tip | 豆知識

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers" class="external-link" target="_blank">'X-'プレフィックスを使用</a>してカスタムの独自ヘッダーを追加できます。

import org.apache.maven.artifact.Artifact;
import org.apache.maven.artifact.repository.ArtifactRepository;
import org.apache.maven.artifact.repository.ArtifactRepositoryPolicy;

/**
 * Base class for artifact resolution exceptions.
 *
 */
public class AbstractArtifactResolutionException extends Exception {
    private String groupId;

    private String artifactId;

    private String version;

    private String type;

 *   <li>Hot thread monitoring for performance analysis</li>
 *   <li>Process isolation with separate JVM</li>
 * </ul>
 */
public class CrawlJob extends ExecJob {

    private static final Logger logger = LogManager.getLogger(CrawlJob.class);

    /**
     * The namespace identifier for the crawling session.
     * Used to organize and identify crawling activities in the system.

package org.codelibs.core.collection;

import static org.hamcrest.CoreMatchers.is;
import static org.junit.Assert.assertThat;

import java.util.Set;

import org.junit.Test;

/**
 * @author higa
 */
public class CaseInsensitiveSetTest {

    /**
     * @throws Exception
     */
    @Test
    public void testContains() throws Exception {
        final Set<String> set = new CaseInsensitiveSet();
        set.add("one");

 */
package org.codelibs.fess.crawler.exception;

/**
 * The crawler login failure exception.
 * This exception is thrown when the crawler fails to login to a website.
 *
 */
public class CrawlerLoginFailureException extends CrawlerSystemException {
    private static final long serialVersionUID = 1L;

    /**
     * Constructs a new CrawlerLoginFailureException with the specified detail message.
     *

import static org.codelibs.core.collection.ArrayUtil.asArray;

import java.security.NoSuchAlgorithmException;

/**
 * Exception that wraps {@link NoSuchAlgorithmException}.
 *
 * @author higa
 */
public class NoSuchAlgorithmRuntimeException extends ClRuntimeException {

    private static final long serialVersionUID = -3176447530746274091L;

    /**
     * Creates a {@link NoSuchAlgorithmRuntimeException}.
     *

import static org.codelibs.core.collection.ArrayUtil.asArray;

import javax.xml.parsers.ParserConfigurationException;

/**
 * Exception that wraps {@link ParserConfigurationException}.
 *
 * @author higa
 */
public class ParserConfigurationRuntimeException extends ClRuntimeException {

    private static final long serialVersionUID = -4610465906028959083L;

    /**
     * Creates a {@link ParserConfigurationRuntimeException}.
     *

 */
package org.codelibs.core.exception;

import java.io.UnsupportedEncodingException;

/**
 * Signals that a character encoding is not supported.
 * @author shinsuke
 */
public class UnsupportedEncodingRuntimeException extends ClRuntimeException {

    private static final long serialVersionUID = 1L;

    /**
     * Creates a new {@link UnsupportedEncodingRuntimeException} with the specified cause.