Eclipselink 2.5 Metamodel Generation using Maven

Question

I would like to know how to generate static metamodels using Maven and Eclipselink 2.5. It worked fine by adding this lines to pom.xml when running Eclipselink 2.4.

// Generate meta model for eclipselink 2.4 (does not work for 2.5)
    <plugin>
                    <groupId>org.bsc.maven</groupId>
                    <artifactId>maven-processor-plugin</artifactId>
                    <version>1.3.1</version>
                    <executions>
                        <execution>
                            <id>process</id>
                            <goals>
                                <goal>process</goal>
                            </goals>
                            <phase>generate-sources</phase>
                            <configuration>
                                <compilerArguments>-Aeclipselink.persistencexml=src/main/resources/META-INF/persistence.xml</compilerArguments>
                                <processors>
                                    <processor>org.eclipse.persistence.internal.jpa.modelgen.CanonicalModelProcessor</processor>
                                </processors>
                                <outputDirectory>${project.build.directory}/generated-sources/meta-model</outputDirectory>
                            </configuration>
                        </execution>
                    </executions>
                </plugin>

But it seems like something has changed since 2.4 cause I get following error:

[INFO] javac option: -proc:only
[INFO] javac option: -Aeclipselink.persistencexml=src/main/resources/META-INF/persistence.xml
[INFO] javac option: -processor
[INFO] javac option: org.eclipse.persistence.internal.jpa.modelgen.CanonicalModelProcessor
[INFO] javac option: -s
[INFO] javac option: /home/asdf/target/generated-sources/meta-model
[INFO] diagnostic error: Annotation processor 'org.eclipse.persistence.internal.jpa.modelgen.CanonicalModelProcessor' not found
[INFO] diagnostic warning: Annotation processing without compilation requested but no processors were found.
[ERROR] execute error
java.lang.Exception: error during compilation
    at org.bsc.maven.plugin.processor.AbstractAnnotationProcessorMojo.executeWithExceptionsHandled(AbstractAnnotationProcessorMojo.java:183)
    at org.bsc.maven.plugin.processor.AbstractAnnotationProcessorMojo.execute(AbstractAnnotationProcessorMojo.java:96)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo(DefaultBuildPluginManager.java:101)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:209)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:153)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute(MojoExecutor.java:145)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:84)
    at org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject(LifecycleModuleBuilder.java:59)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.singleThreadedBuild(LifecycleStarter.java:183)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute(LifecycleStarter.java:161)
    at org.apache.maven.DefaultMaven.doExecute(DefaultMaven.java:320)
    at org.apache.maven.DefaultMaven.execute(DefaultMaven.java:156)
    at org.apache.maven.cli.MavenCli.execute(MavenCli.java:537)
    at org.apache.maven.cli.MavenCli.doMain(MavenCli.java:196)
    at org.apache.maven.cli.MavenCli.main(MavenCli.java:141)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launchEnhanced(Launcher.java:290)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch(Launcher.java:230)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode(Launcher.java:409)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main(Launcher.java:352)

Can you guys out there help me? =)

B.R

Answer 1

It appears that they've moved the CanonicalModelProcessor class to it's own maven artifact:

<dependency>
  <groupId>org.eclipse.persistence</groupId>
  <artifactId>org.eclipse.persistence.jpa.modelgen.processor</artifactId>
  <version>2.5.0</version>
</dependency>

The following maven-processor-plugin configuration works for me:

        <plugin>
            <groupId>org.bsc.maven</groupId>
            <artifactId>maven-processor-plugin</artifactId>
            <version>2.2.4</version>
            <executions>
                <execution>
                    <id>eclipselink-jpa-metamodel</id>
                    <goals>
                        <goal>process</goal>
                    </goals>
                    <phase>generate-sources</phase>
                    <configuration>
                        <processors>
                            <processor>org.eclipse.persistence.internal.jpa.modelgen.CanonicalModelProcessor</processor>
                        </processors>
                        <outputDirectory>${project.build.directory}/generated-sources/meta-model</outputDirectory>
                    </configuration>
                </execution>
            </executions>
            <dependencies>
                <dependency>
                    <groupId>org.eclipse.persistence</groupId>
                    <artifactId>org.eclipse.persistence.jpa.modelgen.processor</artifactId>
                    <version>2.5.0</version>
                    <scope>provided</scope>
                </dependency>
            </dependencies>
        </plugin>

Very important note: the metamodel is generated only if the entities are declared in the persistence unit. It doesn't work with discovered entities.

Answer 2

For me using maven-compiler-plugin from org.apache.maven.plugins resulted in MojoFailureException when using other command than mvn clean install.

The tested the solutions with org.eclipse.persistence.jpa.modelgen.processor 2.6.0.

The configuration in both cases is quite similar.

The main issue which I had with org.bsc.maven was to properly configure the compilerArguments parts. That is why I post (both) the solutions below.

The documentation is available: HERE.

---

Solution using maven-compiler-plugin from org.bsc.maven

For me this one worked better

<plugin>
    <groupId>org.bsc.maven</groupId>
    <artifactId>maven-processor-plugin</artifactId>
    <executions>
        <execution>
            <id>eclipselink-jpa-metamodel</id>
            <goals>
                <goal>process</goal>
            </goals>
            <configuration>
                <compilerArguments>
                    -Aeclipselink.persistencexml=${basedir}/src/main/resources/META-INF/persistence.xml
                </compilerArguments>
                <processors>
                    <processor>org.eclipse.persistence.internal.jpa.modelgen.CanonicalModelProcessor
                    </processor>
                </processors>
            </configuration>
        </execution>
    </executions>
    <dependencies>
        <dependency>
            <groupId>org.eclipse.persistence</groupId>
            <artifactId>org.eclipse.persistence.jpa.modelgen.processor</artifactId>
            <version>${eclipselink.version}</version>
            <scope>compile</scope>
        </dependency>
    </dependencies>
</plugin>

---

Solution using maven-compiler-plugin from org.apache.maven.plugins

<dependency>
    <groupId>org.eclipse.persistence</groupId>
    <artifactId>org.eclipse.persistence.jpa.modelgen.processor</artifactId>
    <version>${eclipselink.version}</version>
    <scope>compile</scope>
</dependency>

...

<plugin>
    <groupId>org.apache.maven.plugins</groupId>
    <artifactId>maven-compiler-plugin</artifactId>
    <configuration>
        <compilerArgs>
            <arg>-Aeclipselink.persistencexml=src/main/resources/META-INF/persistence.xml</arg>
        </compilerArgs>
    </configuration>
</plugin>