我有 2 个实体。 Thread 实体和 Post 实体使用来自 Post->Thread 的 OnetoOne 映射。

Thread 实体包含许多 Posts。我知道我应该使用 OnetoMany 而不是 OnetoOne，但是为了避免所有的集合问题，我使用了 OnetoOne

现在的问题是，当我删除一个Thread 时，所有与之关联的post 也必须被删除。 我通过使用成功地做到了

@OnDelete(action = OnDeleteAction.CASCADE)

但它只适用于 Postgres 和 Ms-SQl，不适用于 MySql(也尝试过 InnoDb)。 on delete 级联 不是在架构生成查询中生成的。

代码如下

//Thread Entity
@Id
@GeneratedValue
@Column(name = "thread_id")
private int ThreadID;

//Post Entity
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "post_id")
private int PostID;

@OneToOne()
@OnDelete(action = OnDeleteAction.CASCADE)
private thread ThreadID;

使用以下查询从 Thread 实体中删除项目时出现以下错误

session.delete(session.load(thread.class,1));

Sep 02, 2014 8:33:51 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions WARN: SQL Error: 1451, SQLState: 23000 Sep 02, 2014 8:33:51 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions ERROR: Cannot delete or update a parent row: a foreign key constraint fails (forum.post_tbl, CONSTRAINT FK_bfbv5nknqj7ppd5630scimhtb FOREIGN KEY (ThreadID_thread_id) REFERENCES thread_tbl (thread_id)) org.hibernate.exception.ConstraintViolationException: could not execute statement at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:74) at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:49) at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:125) at org.hibernate.engine.jdbc.spi.SqlExceptionHelper.convert(SqlExceptionHelper.java:110) at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:136) at org.hibernate.engine.jdbc.batch.internal.NonBatchingBatch.addToBatch(NonBatchingBatch.java:58) at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3343) at org.hibernate.persister.entity.AbstractEntityPersister.delete(AbstractEntityPersister.java:3546) at org.hibernate.action.internal.EntityDeleteAction.execute(EntityDeleteAction.java:100) at org.hibernate.engine.spi.ActionQueue.execute(ActionQueue.java:377) at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:369) at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:293) at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:339) at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:52) at org.hibernate.internal.SessionImpl.flush(SessionImpl.java:1234) at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:404) at org.hibernate.engine.transaction.internal.jdbc.JdbcTransaction.beforeTransactionCommit(JdbcTransaction.java:101) at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.commit(AbstractTransactionImpl.java:175) at test.main(test.java:84) Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (forum.post_tbl, CONSTRAINT FK_bfbv5nknqj7ppd5630scimhtb FOREIGN KEY (ThreadID_thread_id) REFERENCES thread_tbl (thread_id)) HibernateException : could not execute statement at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:408) at com.mysql.jdbc.Util.handleNewInstance(Util.java:411) at com.mysql.jdbc.Util.getInstance(Util.java:386) at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1040) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4120) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4052) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2503) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2664) at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2794) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2458) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2375) at com.mysql.jdbc.PreparedStatement.executeUpdate(PreparedStatement.java:2359) at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:133) ... 14 more BUILD SUCCESSFUL (total time: 2 seconds)

请帮我想办法解决这个问题。

最佳答案

这就是我基于Spring Boot解决这个问题的方法。

解决方案

来自

// application.properties  
spring.jpa.database-platform=org.hibernate.dialect.MySQLDialect

到

spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect

解释
如下所示，MySQL5InnoDBDialect.java 中 CascadeDelete 的默认值似乎只支持 Cascade。

// MySQLDialect.java
@Override
    public boolean supportsCascadeDelete() {
        return false;
    }

// MySQL5InnoDBDialect.java
@Override
    public boolean supportsCascadeDelete() {
        return true;
    }

关于java - Hibernate OnDelete Cascade 不适用于 MySql 但适用于 postgres 和 Ms-Sql，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/25626675/