Generic Spring Data JPA repository implementation to load data by class type

Question

I am using Spring Data JPA 1.4.3.RELEASE with Hibernate 4.2.7.Final I was able to successfully create a Base Repository class, something on the lines of : http://docs.spring.io/spring-data/jpa/docs/1.4.2.RELEASE/reference/html/repositories.html#repositories.custom-behaviour-for-all-repositories

            @NoRepositoryBean
            public interface BaseRepository <T extends BaseEntity, ID extends Serializable>
            extends JpaRepository<T, ID>

            @NoRepositoryBean
            public class BaseRepositoryImpl<T extends BaseEntity, ID extends Serializable>
            extends SimpleJpaRepository<T, ID> implements BaseRepository<T, ID> {

I am able to sucessfully work with :

            public interface FlowerRepository extends BaseRepository<Flower, Long> {

Now, I am trying to write an generic implementation(that extends the base repository) to load all reference data like Flower types. That is because I do not want to have a repository for every single "type" data or "reference" data. I want to be able to manage that using a generic repository by passing a specific "class" type(that implements a interface specific to reference data type).For E-g

            loadAll(FlowerType.class)

I use HBMs to map hibernate entities so I have :

            <?xml version="1.0"?>
            <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
            "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
            <hibernate-mapping>
                <class name="xxx.FlowerType" table="FLWTYP">
                <meta attribute="extends" inherit="false">xxx.BaseReferenceType</meta>
                <id name="primaryKey" type="string">
                    <column name="TYP_CDE" length="5" />
                    <generator class="assigned" />
                </id>

            public class FlowerType extends BaseReferenceType<String> implements ReferenceEntity<String>

            public abstract class BaseReferenceEntity<T extends Serializable> extends BaseEntity implements
    ReferenceEntity<T>

            public abstract class BaseEntity implements DomainEntity

            public interface ReferenceEntity<PK extends Serializable> {

Persistence XML :

            <?xml version="1.0" encoding="UTF-8" standalone="no"?>
            <persistence xmlns="http://java.sun.com/xml/ns/persistence"
                xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.0"
                xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
                <persistence-unit name="xxxPU"
                    transaction-type="RESOURCE_LOCAL">
                    <provider>org.hibernate.ejb.HibernatePersistence</provider>
                    <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>
                    <properties>
                        <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect" />
                        <property name="hibernate.hbm2ddl.auto" value="none" />
                        <property name="hibernate.ejb.naming_strategy" value="org.hibernate.cfg.ImprovedNamingStrategy" />
                        <property name="hibernate.connection.charSet" value="UTF-8" />
                        <property name="hibernate.jdbc.batch_size" value="100" />
                        <property name="hibernate.show_sql" value="false" />
                        <property name="hibernate.format_sql" value="false" />
                        <property name="hibernate.transaction.flush_before_completion"
                            value="false" />
                        <property name="hibernate.connection.autocommit" value="false" />
                        <property name="hibernate.ejb.cfgfile" value="hibernate.cfg.xml"/>
                        <property name="jadira.usertype.autoRegisterUserTypes" value="true" />
                        <property name="jadira.usertype.databaseZone" value="jvm" />
                        <property name="jadira.usertype.javaZone" value="jvm" />
                    </properties>
                </persistence-unit>
            </persistence>

Hibernate config :

            <?xml version="1.0" encoding="UTF-8"?>
            <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                                 "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
            <hibernate-configuration>
                <session-factory>
                    <mapping resource="FlowerType.hbm.xml"/>
                    <mapping resource="Flower.hbm.xml"/>
                </session-factory>
            </hibernate-configuration>

So I looked at some tutorial links and SO posts and did some work based on :

Spring Jpa adding custom functionality to all repositories and at the same time other custom funcs to a single repository

I have :

            @NoRepositoryBean
            public interface CustomReferenceDataRepository<T extends BaseEntity & ReferenceEntity<PK>, PK extends Serializable> {
                public Map<PK, T> findAll(Class<T> clz);
            }

            public interface ReferenceDataRepository extends BaseRepository, CustomReferenceDataRepository {
            }

            public class ReferenceDataRepositoryImpl<T extends BaseEntity & ReferenceEntity<PK>, PK extends Serializable>
                    implements CustomReferenceDataRepository<T, PK> {

                @PersistenceContext
                private EntityManager em;


                @Override
                public Map<PK, T> findAll(Class<T> clz) {
                //do whatever
                    return null;
                }

            }

Ended up with a exception :

            Caused by: java.lang.IllegalArgumentException: Not an managed type: class xxx.BaseEntity
                at org.hibernate.ejb.metamodel.MetamodelImpl.managedType(MetamodelImpl.java:200) ~[hibernate-entitymanager-4.2.7.Final.jar:4.2.7.Final]
                at org.springframework.data.jpa.repository.support.JpaMetamodelEntityInformation.<init>(JpaMetamodelEntityInformation.java:68) ~[spring-data-jpa-1.4.3.RELEASE.jar:na]
                at org.springframework.data.jpa.repository.support.JpaEntityInformationSupport.getMetadata(JpaEntityInformationSupport.java:65) ~[spring-data-jpa-1.4.3.RELEASE.jar:na]
                at org.springframework.data.jpa.repository.support.JpaRepositoryFactory.getEntityInformation(JpaRepositoryFactory.java:146) ~[spring-data-jpa-1.4.3.RELEASE.jar:na]

I understand Hibernate does not manage "BaseEntity" but am not able to figure out what I am missing.

Is my requirement of implementing a generic repository for reference data even possible ? If yes, what am I doing wrong ? Any guidance appreciated. Thanks.

Answer 1

You have to add mapping for BaseEntity as well:

<class name="xxx.BaseEntity " abstract="true">

You can also try to use annotations and just set packagesToScan property