Maven + Spring + Hibernate: hibernate3-maven-plugin hbm2ddl fails for reason “Caused by: java.lang.NullPointerException”

Question

I had to downgrade Hibernate from version 4 to version 3 (3.3.2.GA to be specific), due to current lack of support for Hibernate 4 within Spring, and now the project fails t

Answer 1

For a large project (more than 250 Entities), I use the following pom.xml witch works fine and generate the schema during the compile phase. Note : persistence.xml specifies the database dialect.

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>test</groupId>
<artifactId>jpa</artifactId>
<version>1.0-SNAPSHOT</version>

<dependencies>
    <!-- java EE (for annotations) -->
    <dependency>
        <groupId>javax</groupId>
        <artifactId>javaee-api</artifactId>
        <version>6.0</version>
        <scope>provided</scope>
    </dependency>
</dependencies>

<build>
    <plugins>

        <!-- hibernate hmb2ddl plugin configuration -->
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>hibernate3-maven-plugin</artifactId>
            <version>3.0</version>
            <executions>
                <execution>
                    <id>generate.database.schema.from.ejb.annotation</id>
                    <phase>compile</phase>
                    <goals>
                        <goal>run</goal>
                    </goals>
                    <configuration>
                        <hibernatetool>
                            <classpath><path location="src/main/java"/></classpath>
                            <hbm2ddl console="false" export="false" update="false"
                                drop="false" create="true" outputfilename="create.sql" format="false"
                                haltonerror="true">
                                <jpaconfiguration persistenceunit="persist" />
                            </hbm2ddl>
                        </hibernatetool>
                    </configuration>
                </execution>
            </executions>
            <dependencies>
                <!-- hibernate tools -->
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-core</artifactId>
                    <version>3.6.10.Final</version>
                </dependency>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-entitymanager</artifactId>
                    <version>3.6.10.Final</version>
                </dependency>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-validator</artifactId>
                    <version>4.1.0.Final</version>
                </dependency>
                <dependency>
                    <groupId>javassist</groupId>
                    <artifactId>javassist</artifactId>
                    <version>3.4.GA</version>
                </dependency>
            </dependencies>
        </plugin>

    </plugins>
</build>

Answer 2

I faced the same problem while trying to make maven bootstrap a database from a hibernate model (issue described in Generate database schema (Hibernate) on maven test).

I got hbm2ddl working quite well with the following combination of versions: Hibernate (runtime): 4.1.7.Final hibernate3-maven-plugin: 3.6.10.Final, specified plugin version 2.2 hibernate3-maven-plugin's hibernate-validator dependency: 4.2.0.Final

Below the relevant parts of the pom:

Versions:

<properties>

    <org.hibernate.version>4.1.7.Final</org.hibernate.version>
    <hibernate.maven.plugin.version>3.6.10.Final</hibernate.maven.plugin.version>

</properties>

hibernate3-maven-plugin's definition:

<build>
    <plugins>
        <plugin>
            <groupId>org.codehaus.mojo</groupId>
            <artifactId>hibernate3-maven-plugin</artifactId>
            <version>2.2</version>
            <configuration>
                <components>
                    <component>
                        <name>hbm2ddl</name>
                        <implementation>jpaconfiguration</implementation>
                    </component>

                </components>

                <componentProperties>
                    <outputfilename>schema.ddl</outputfilename>
                    <create>true</create>
                    <export>false</export>
                    <format>true</format>
                    <drop>false</drop>
                    <jdk5>true</jdk5>
                    <propertyfile>target/test-classes/application.properties</propertyfile>
                    <skip>${skipTests}</skip>
                </componentProperties>
            </configuration>
            <executions>
                <execution>
                    <phase>process-classes</phase>
                    <goals>
                        <goal>hbm2ddl</goal>
                    </goals>
                </execution>
            </executions>
            <dependencies>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-entitymanager</artifactId>
                    <version>${hibernate.maven.plugin.version}</version>
                    <exclusions>
                        <exclusion>
                            <groupId>cglib</groupId>
                            <artifactId>cglib</artifactId>
                        </exclusion>
                        <exclusion>
                            <groupId>commons-logging</groupId>
                            <artifactId>commons-logging</artifactId>
                        </exclusion>
                    </exclusions>
                </dependency>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-core</artifactId>
                    <version>${hibernate.maven.plugin.version}</version>
                    <exclusions>
                        <exclusion>
                            <groupId>cglib</groupId>
                            <artifactId>cglib</artifactId>
                        </exclusion>
                        <exclusion>
                            <groupId>commons-logging</groupId>
                            <artifactId>commons-logging</artifactId>
                        </exclusion>
                    </exclusions>
                </dependency>
                <dependency>
                    <groupId>org.hibernate</groupId>
                    <artifactId>hibernate-validator</artifactId>
                    <version>4.2.0.Final</version>
                </dependency>

            </dependencies>
        </plugin>

    </plugins>
</build>

Runtime dependencies:

<dependencies>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>${org.hibernate.version}</version>
    </dependency>

    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>${org.hibernate.version}</version>
    </dependency>
</dependencies>

I hope this helps.