Java 不能在 CrudRepository 上使用 delete()

Cannot use delete() on CrudRepository

提问by webhammer

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.

我第一次使用最新的 spring (4.0.4) 和 Hibernate (4.3.5) 和 spring-data-jpa (1.6.0) 并且无法让存储库在 MySQL 表上工作以进行写入或删除数据。它读取数据很好，但是当我尝试删除时，没有任何反应。如果我使用 H2 数据库一切正常，但是当我将数据源切换为 MySQL 服务器时，delete() 停止工作。

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?

问题 1：为什么当我使用 MySQL 数据源时 CrudRepository 子类不能从我的表实体中删除行，但如果我使用 H2 数据源，它可以使用相同的代码？

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

如果我在 CrudRepository 的子类中创建这样的函数，我可以删除数据：

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:

我希望我错过了一些简单的东西。但是在我的单元测试类中，我有这个自动装配的存储库参考：

@Autowired
MyEntityRepository myEntityRepository;

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

当我使用 MySQL 数据源时，这些命令什么都不做（它们甚至不会出现运行时错误）：

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:

这是我使用此代码创建的 2 个数据源（H2 已注释掉）和实体管理器工厂：

@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:

编辑：我已将以下内容添加到我的 log4j.xml 中：

<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:

当我在 Repository 子类中取消注释我的方法时，我会在控制台中得到这个：

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!

并且删除成功！

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

但是，如果我将存储库子类方法注释掉，我会在控制台中得到它：

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?

删除失败和这个消息有关系吗？

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...

我不确定那是什么意思...

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?

问题 2：我是否必须为每个需要基本 CRUD 操作的表创建子类 CrudRepository，还是可以使用对表实体类的引用在运行时为给定表创建 CrudRepository？

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?

问题3：如果我需要在大量的CrudRepository子类上手动创建我的delete和insert方法，在MySQL中给定表生成表实体和DAO或存储库类有什么建议吗？

采纳答案by webhammer

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.

我发现问题的根源在于我使用单元测试运行我的代码。显然，单元测试被设置为自动回滚的事务，但我找不到支持它的文档。我的单元测试是在表中创建一行，然后根据它的 ID 删除该行。它总是失败，因为它总是在回滚事务。

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

如果您需要实际执行删除操作的单元测试，请添加 rollback(false) 注释，以便您的单元测试方法如下所示：

@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 );
}