在 Spring Data JPA 中处理实体继承的最佳方式 [英] Best way of handling entities inheritance in Spring Data JPA

问题描述

我有三个 JPA 实体 类 A、B 和 C，具有以下层次结构:>

I've three JPA entity classes A, B and C with the following hierarchy:

    A
    |
+---+---+
|       |
C       B

即:

@Entity
@Inheritance
public abstract class A { /* ... */ }

@Entity
public class B extends A { /* ... */ }

@Entity
public class C extends A { /* ... */ }

使用Spring Data JPA，为此类实体编写存储库类的最佳方法是什么?

Using Spring Data JPA, what is the best way to write repositories classes for such entities?

我知道我可以写这些:

public interface ARespository extends CrudRepository<A, Long> { }

public interface BRespository extends CrudRepository<B, Long> { }

public interface CRespository extends CrudRepository<C, Long> { }

但是如果在 A 类中有一个字段 name 并且我在 ARepository 中添加了这个方法:

but if in the class A there is a field name and I add this method in the ARepository:

public A findByName(String name);

我必须在其他两个存储库中也编写这样的方法，这有点烦人..有没有更好的方法来处理这种情况?

I've to write such method also in the other two repositories, and this is a bit annoying.. Is there a better way to handle such situation?

我想要的另一点是 ARespository 应该是一个只读存储库(即扩展 Repository 类)，而其他两个存储库应该公开所有CRUD 操作.

Another point I would like to have is that ARespository should be a read-only repository (i.e. extend the Repository class) while the other two repositories should expose all the CRUD operations.

告诉我可能的解决方案.

Let me know possible solutions.

推荐答案

我使用了同样在 这篇文章 来自 Netgloo 的博客.

I used the solution also described in this post from Netgloo's blog.

这个想法是创建一个通用存储库类，如下所示:

The idea is to create a generic repository class like the following:

@NoRepositoryBean
public interface ABaseRepository<T extends A> 
extends CrudRepository<T, Long> {
  // All methods in this repository will be available in the ARepository,
  // in the BRepository and in the CRepository.
  // ...
}

那么我可以这样写三个仓库:

then I can write the three repositories in this way:

@Transactional
public interface ARepository extends ABaseRepository<A> { /* ... */ }

@Transactional
public interface BRepository extends ABaseRepository<B> { /* ... */ }

@Transactional
public interface CRepository extends ABaseRepository<C> { /* ... */ }

此外，要获得 ARepository 的只读存储库，我可以将 ABaseRepository 定义为只读:

Moreover, to obtain a read-only repository for ARepository I can define the ABaseRepository as read-only:

@NoRepositoryBean
public interface ABaseRepository<T> 
extends Repository<T, Long> {
  T findOne(Long id);
  Iterable<T> findAll();
  Iterable<T> findAll(Sort sort);
  Page<T> findAll(Pageable pageable);
}

并且从 BRepository 还扩展 Spring Data JPA 的 CrudRepository 以实现读/写存储库:

and from BRepository extend also the Spring Data JPA's CrudRepository to achieve a read/write repository:

@Transactional
public interface BRepository 
extends ABaseRepository<B>, CrudRepository<B, Long> 
{ /* ... */ }

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