引起：org.hibernate.MappingException：属性映射的列数错误：

Question

我正在开发Spring Boot + Spring Data JPA + MYSQL示例。在此示例中，我在尝试运行示例时遇到以下错误。电影表有列special_features set('Trailers','Commentaries','Deleted Scenes','Behind the Scenes') DEFAULT NULL,。在 pojo 类中，我使用如下 -@Column(name="special_features")private Object specialFeatures;错误：-org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFactory; nested exception is org.hibernate.MappingException: property mapping has wrong number of columns: com.example.model.Film.specialFeatures type: object    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1694) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:573) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317) ~[spring-beans-5.0.10.RELEASE.jar:5.0.10.RELEASE]

Answer 1

Hibernate 无法处理开箱即用的 SET 数据类型。即使可以，如果将其映射到通用对象是一种方法，我也会感到惊讶。Hibernate 没有机会将其转换回字符串。

您需要做的是实现一个 AttributeConverter，它将字符串从 DB 转换为合适的数据类型，例如 EnumSet，反之亦然。看看这里的例子：Mapping EnumSet to mysql Set using JPA 2.1