Spring Data JPA中关系@ManyToOne的查询方法

Question

错误：

beanCreationException：创建名为“post repository”的bean时出错：FactoryBean在创建对象时引发异常；嵌套异常为java.lang.IllegalArgumentException：无法为方法public抽象org.springframework.data.domain.page com.example.forumproject.authentication.repository.postrepository.findByTags（java.util.list,org.springframework.data.domain.pagable）创建查询！标记上的操作符SIMPLE_PROPERTY需要一个标量参数，在方法public abstract org.springframework.data.domain.page com.example.forumproject.authentication.repository.postrepository.findByTags（java.util.list,org.springframework.data.domain.pagable）中找到了接口java.util.list。

这是定义的Post类：

@EqualsAndHashCode(callSuper = true)
@Entity
@Data
@Table(name = "posts", uniqueConstraints = { @UniqueConstraint(columnNames = { "title" }) })
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class Post extends UserDateAudit {
    ... 
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "user_id")
    private User user;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "category_id")
    private Category category;

    @JsonIgnore
    @OneToMany(mappedBy = "post", cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Comment> comments;

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(name = "post_tag", joinColumns = @JoinColumn(name = "post_id", referencedColumnName = "id"), inverseJoinColumns = @JoinColumn(name = "tag_id", referencedColumnName = "id"))
    private List<Tag> tags;

存储库：

@Repository
public interface PostRepository extends JpaRepository<Post, Long> {
    Page<Post> findByCreatedBy(Long userId, Pageable pageable);

    Page<Post> findByCategory(Long categoryId, Pageable pageable);

    Page<Post> findByTags(List<Tag> tags, Pageable pageable);

    Long countByCreatedBy(Long userId);
}

Answer 1

如果我们希望使用in子句进行具有Spring Data JPA规范动态查询

我们需要在方法名中使用关键字in，如下所示。

Page<Post> findByTagsIn(List<Tag> tags, Pageable pageable);

您可以在这里找到方法名称中所有支持的关键字