Spring Data 是个好东西,极大简化了后端dao的操作,只需要在 dao 接口写个 findByXXX 的方法就能自动实现按条件查询这个简直太爽了。但是在实际使用过程中,可能会遇到一个持久化逻辑删除的问题。那么问题来了。spring data jpa并不支持逻辑删除。那如何处理?
在互联网项目中,通常删除都不是物理删除,而是逻辑删除。
那么在展示数据的时候需要过滤掉已删除的数据。而@Where 注解可以说就是为此而设计的。
package org.hibernate.annotations; import java.lang.annotation.Retention; import java.lang.annotation.Target; import static java.lang.annotation.ElementType.FIELD; import static java.lang.annotation.ElementType.METHOD; import static java.lang.annotation.ElementType.TYPE; import static java.lang.annotation.RetentionPolicy.RUNTIME; /** * Where clause to add to the element Entity or target entity of a collection. The clause is written in SQL. * A common use case here is for soft-deletes. * * @author Emmanuel Bernard */ @Target({TYPE, METHOD, FIELD}) @Retention(RUNTIME) public @interface Where { /** * The where-clause predicate. */ String clause(); }
这玩意儿乍一看很美好。但是实际不然。这样做将所有的删除方法都覆盖了。当我想要用到物理删除的时候。就不能用了。于是再次出发。寻找一种更加美妙的解决方案。终于让我找到了。话不多说。直接放码。
@NoRepositoryBean public interface BaseDao<T extends BaseEntry, ID extends Serializable> extends PagingAndSortingRepository<T, ID> { @Override @Transactional(readOnly = true) @Query("select e from #{#entityName} e where e.deleted = false") List<T> findAll(); @Override @Transactional(readOnly = true) @Query("select e from #{#entityName} e where e.id in ?1 and e.deleted = false") Iterable<T> findAll(Iterable<ID> ids); @Override @Transactional(readOnly = true) @Query("select e from #{#entityName} e where e.id = ?1 and e.deleted = false") T findOne(ID id); @Override @Transactional(readOnly = true) @Query("select count(e) from #{#entityName} e where e.deleted = false") long count(); @Override @Transactional(readOnly = true) default boolean exists(ID id) { return findOne(id) != null; } @Query("update #{#entityName} e set e.deleted = true where e.id = ?1") @Transactional @Modifying void logicDelete(ID id); @Transactional default void logicDelete(T entity) { logicDelete((ID) entity.getId()); } @Transactional default void logicDelete(Iterable<? extends T> entities) { entities.forEach(entity -> logicDelete((ID) entity.getId())); } @Query("update #{#entityName} e set e.deleted = true ") @Transactional @Modifying void logicDeleteAll(); }
BaseEntry代码如下:
@Data @MappedSuperclass public class BaseEntry implements Serializable { private static final long serialVersionUID = 5966306766659220492L; @Id protected String id; @Temporal(TemporalType.TIMESTAMP) protected Date createdDate; protected String createdBy; @Temporal(TemporalType.TIMESTAMP) protected Date updatedDate; protected String updatedBy; protected Boolean deleted = false; }