无法在CrudRepository上使用delete（）

Question

I'm using the latest spring (4.0.4) and Hibernate (4.3.5) and spring-data-jpa (1.6.0) for the first time and am having trouble getting the repository to work on a MySQL table to write or delete data. It's reading data fine, but when I try to delete, nothing happens. Things work fine if I use an H2 database, but when I switch my data source to be a MySQL server, delete() stops working.

Question 1: Why isn't the CrudRepository sub-class able to delete rows from my table entity when I use a MySQL data source, but it works with the same code if I use an H2 data source?

I can delete data if I create functions like this in my sub-class of CrudRepository:

public interface MyEntityRepository extends CrudRepository<MyEntity, Long> {
    @Modifying
    @Query("delete from MyEntity where entity_id = ?1")
    void delete(Long entityId);

    @Modifying
    @Query("delete from StageTeacher")
    void deleteAll();
}

I am hoping I'm missing something simple. But in my unit test class, I've got this autowired repository reference:

@Autowired
MyEntityRepository myEntityRepository;

When I'm using the MySQL data source these commands do nothing (they don't even case a run-time error):

myEntityRepository.deleteAll();
myEntityRepository.delete(myEntity.getId());

Here's the 2 data sources (H2 is commented out) and the entity manager factory I create using this code:

@Bean
public EntityManagerFactory entityManagerFactory() throws SQLException {
    DriverManagerDataSource dataSource = new DriverManagerDataSource();
    dataSource.setDriverClassName("com.mysql.jdbc.Driver");
    dataSource.setUrl("jdbc:mysql://<host name>:3306/<schema name>");
    dataSource.setUsername("<username>");
    dataSource.setPassword("<password>");

    /*
    EmbeddedDatabaseBuilder builder = new EmbeddedDatabaseBuilder();
    DriverManagerDataSource dataSource = builder.setType(EmbeddedDatabaseType.H2).build();
    */

    HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
    // used when I have H2 enabled
    //vendorAdapter.setGenerateDdl(true);

    LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
    factory.setJpaVendorAdapter(vendorAdapter);

    Properties properties = new Properties();
    properties.setProperty("hibernate.show_sql", "true");
    properties.setProperty("hibernate.dialect", "org.hibernate.dialect.MySQLMyISAMDialect");
    factory.setJpaProperties(properties);

    factory.setPackagesToScan("<package with table entity classes>");
    factory.setDataSource(dataSource);
    factory.afterPropertiesSet();

    return factory.getObject();
}

EDIT: I've added the following to my log4j.xml:

<logger name="org.hibernate">
    <level value="DEBUG"/>
</logger>
<logger name="org.springframework.data">
    <level value="DEBUG"/>
</logger>

I get this in the console when I have my methods un-commented in the Repository sub-class:

DEBUG [main] IntegrationTests.delete(54) | >>>>>>>>>> delete all??
DEBUG [main] AbstractTransactionImpl.begin(160) | begin
DEBUG [main] LogicalConnectionImpl.obtainConnection(226) | Obtaining JDBC connection
DEBUG [main] LogicalConnectionImpl.obtainConnection(232) | Obtained JDBC connection
DEBUG [main] JdbcTransaction.doBegin(69) | initial autocommit status: true
DEBUG [main] JdbcTransaction.doBegin(71) | disabling autocommit
Hibernate: delete from stage_teacher
DEBUG [main] AbstractTransactionImpl.commit(175) | committing
DEBUG [main] JdbcTransaction.doCommit(113) | committed JDBC Connection
DEBUG [main] JdbcTransaction.releaseManagedConnection(126) | re-enabling autocommit
DEBUG [main] LogicalConnectionImpl.releaseConnection(246) | Releasing JDBC connection
DEBUG [main] LogicalConnectionImpl.releaseConnection(264) | Released JDBC connection

and the delete succeeds!

However, if I comment the repository sub-class methods out, I'll get this in the console:

DEBUG [main] IntegrationTests.delete(54) | >>>>>>>>>> delete??
DEBUG [main] AbstractTransactionImpl.begin(160) | begin
DEBUG [main] LogicalConnectionImpl.obtainConnection(226) | Obtaining JDBC connection
DEBUG [main] LogicalConnectionImpl.obtainConnection(232) | Obtained JDBC connection
DEBUG [main] JdbcTransaction.doBegin(69) | initial autocommit status: true
DEBUG [main] JdbcTransaction.doBegin(71) | disabling autocommit
Hibernate: select stageteach0_.entity_id as entity_i1_0_0_, stageteach0_.active as active2_0_0_, stageteach0_.alias as alias3_0_0_, stageteach0_.allow_marketing_emails as allow_ma4_0_0_, stageteach0_.allow_password_resets as allow_pa5_0_0_, stageteach0_.console_setting_id as console_6_0_0_, stageteach0_.date_created as date_cre7_0_0_, stageteach0_.date_deactivated as date_dea8_0_0_, stageteach0_.date_modified as date_mod9_0_0_, stageteach0_.default_role_id as default10_0_0_, stageteach0_.district_teacher_id as distric11_0_0_, stageteach0_.email_address as email_a12_0_0_, stageteach0_.first_name as first_n13_0_0_, stageteach0_.first_name_localized as first_n14_0_0_, stageteach0_.iid as iid15_0_0_, stageteach0_.last_name as last_na16_0_0_, stageteach0_.last_name_localized as last_na17_0_0_, stageteach0_.main_teacher_id as main_te18_0_0_, stageteach0_.password as passwor19_0_0_, stageteach0_.pref_language_id as pref_la20_0_0_, stageteach0_.rest_id as rest_id21_0_0_, stageteach0_.salutation_id as salutat22_0_0_, stageteach0_.school_teacher_id as school_23_0_0_, stageteach0_.status_id as status_24_0_0_, stageteach0_.tcd as tcd25_0_0_, stageteach0_.teacher_type_id as teacher26_0_0_, stageteach0_.username as usernam27_0_0_ from stage_teacher stageteach0_ where stageteach0_.entity_id=?
DEBUG [main] ResultSetProcessorImpl.extractResults(127) | Starting ResultSet row #0
DEBUG [main] EntityReferenceInitializerImpl.resolveEntityKey(142) | On call to EntityIdentifierReaderImpl#resolve, EntityKey was already known; should only happen on root returns with an optional identifier specified
DEBUG [main] TwoPhaseLoad.doInitializeEntity(160) | Resolving associations for [org.mind.gen40.domain.gen40.StageTeacher#10956]
DEBUG [main] TwoPhaseLoad.doInitializeEntity(286) | Done materializing entity [org.mind.gen40.domain.gen40.StageTeacher#10956]
DEBUG [main] AbstractLoadPlanBasedEntityLoader.load(208) | Done entity load : org.mind.gen40.domain.gen40.StageTeacher#10956
DEBUG [main] AbstractTransactionImpl.commit(175) | committing
DEBUG [main] JdbcTransaction.doCommit(113) | committed JDBC Connection
DEBUG [main] JdbcTransaction.releaseManagedConnection(126) | re-enabling autocommit
DEBUG [main] LogicalConnectionImpl.releaseConnection(246) | Releasing JDBC connection
DEBUG [main] LogicalConnectionImpl.releaseConnection(264) | Released JDBC connection

Does the failure to delete have something to do with this message?

On call to EntityIdentifierReaderImpl#resolve, EntityKey was already known; should only happen on root returns with an optional identifier specified

I'm not sure what that means...

Question 2: Do I have to sub-class CrudRepository for each table that I need basic CRUD operations on, or can I use a reference to the table entity class to create a CrudRepository at run-time for a given table?

Question 3: If I need to manually create my delete and insert methods on a large number of CrudRepository sub-classes, are there any suggestions on generating table entities and DAO or repository classes given tables in MySQL?

Answer 1

I've discovered that the problem was rooted in the fact that I was running my code using a unit test. Apparently unit tests are setup as transactions that are automatically rolled back, but I can't find documentation to support that. My unit test was creating a row in a table and then deleting the row based on it's ID. It was always failing because it was always rolling back the transaction.

If you need unit tests that actually do a delete then add the rollback(false) annotation so your unit test method looks like this:

@Autowired
MyEntityRepository myEntityRepository;

@Test
@Rollback(false)
public void createAndThenDeleteRow() {
    MyEntity testRecord = new TestRecord( "fake", "data" );
    TestRecord savedRecord = myEntityRepository.save( testRecord );
    Long id = savedRecord.getId();
    TestRecord loadedRecord = myEntityRepository.findOne( id );
    assertNotNull( loadedRecord );
    myEntityRepository.delete( id );
    TestRecord reloadedRecord = myEntityRepository.findOne( id );
    assertNull( reloadedRecord );
}