# Migra de Pydantic v1 a Pydantic v2 { #migrate-from-pydantic-v1-to-pydantic-v2 }

Si tienes una app de FastAPI antigua, podrías estar usando Pydantic versión 1.

FastAPI ha tenido compatibilidad con Pydantic v1 o v2 desde la versión 0.100.0.

Si tenías instalado Pydantic v2, lo usaba. Si en cambio tenías Pydantic v1, usaba ese.

<project>
  <modelVersion>4.0.0</modelVersion>
  <groupId>maven</groupId>
  <artifactId>p0</artifactId>
  <packaging>pom</packaging>
  <version>1.0</version>

  <build>
    <plugins>
      <plugin>
        <groupId>org.apache.maven.plugins</groupId>
        <artifactId>maven-compiler-plugin</artifactId>
        <executions>
          <execution>
            <id>test</id>

            <!--  The key to this test... -->

        InternalMavenSession mSession = InternalMavenSession.from(iSession);
        MavenSession session = mSession.getMavenSession();

        session.setProjects(projects);
        session.setAllProjects(session.getProjects());

        return session;
    }

    protected void initRepoSession(

Sebastián Ramírez <******@****.***> 1722919710 -0500

            throws UnresolvableModelException {
        File pomFile = null;

        if (modelPool != null) {
            pomFile = modelPool.get(groupId, artifactId, version);
        }

        if (pomFile == null) {
            Artifact pomArtifact = new DefaultArtifact(groupId, artifactId, "", "pom", version);

            try {

			<artifactId>lasta-di</artifactId>
			<version>${lasta.di.version}</version>
		</dependency>
		<dependency>
			<groupId>org.lastaflute</groupId>
			<artifactId>lastaflute</artifactId>
			<version>${lastaflute.version}</version>
		</dependency>
		<dependency>
			<groupId>org.lastaflute.html</groupId>
			<artifactId>lasta-taglib</artifactId>
			<version>${lasta.taglib.version}</version>
		</dependency>

| versions        | msgp int                    | Number of versions following
| header_1        | msgp bin array              | Header of version 1
| metadata_1      | msgp bin array              | Metadata of version 1
| ...header_n     | msgp bin array              | Header of last version
| ...metadata_n   | msgp bin array              | Metadata of last version

Each header contains a mspg array (tuple) encoded object:

        RepositoryCache cache = session.getCache();
        if (cache != null && !ConfigUtils.getBoolean(session, false, "aether.versionResolver.noCache")) {
            cacheKey = new Key(session, request);

            Object obj = cache.get(session, cacheKey);
            if (obj instanceof Record record) {
                result.setVersion(record.version);
                result.setRepository(

            String message,
            String groupId,
            String artifactId,
            String version,
            String type,
            String classifier,
            List<ArtifactRepository> remoteRepositories,
            List<String> path) {
        this(message, groupId, artifactId, version, type, classifier, remoteRepositories, path, null);
    }

    @SuppressWarnings("checkstyle:parameternumber")

     * Resolves an artifact's meta version (if any) to a concrete version.
     * For example, resolves "1.0-SNAPSHOT" to "1.0-20090208.132618-23".
     *
     * @param session The repository session, must not be {@code null}.
     * @param artifactCoordinates The artifact coordinates for which the version needs to be resolved, must not be {@code null}
     * @return The version result, never {@code null}.