javatwosidejoin在JPA标准构建中的应用
我有三个实体,就像这样:-
@Entity
@Table(name = "product")
public class Product {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id")
@Expose
private long id;
@ManyToOne
@JoinColumn(name = "users_id")
@Expose
private User user;
}
@Entity
@Table(name = "users")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id")
@Expose
private long id;
}
@Entity
@Table(name = "users_phone")
public class UserPhone {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id")
@Expose
private int id;
@ManyToOne
@JoinColumn(name = "users_id")
@Expose
private User user;
}
现在,我想在连接三个表的基础上,从product表中得到结果。我可以将其传递到存储库中,这样我就可以将其传递到存储库中。以下是规范代码
Specification<ProductPost> productSpecification = new Specification<ProductPost>() {
@Override
public Predicate toPredicate(Root<ProductPost> root, CriteriaQuery<?> criteriaQuery, CriteriaBuilder criteriaBuilder) {
List<Predicate> predicates = new ArrayList<>();
criteriaQuery = criteriaBuilder.createQuery();
if (userName.length() > 0) {
predicates.add(criteriaBuilder.like(root.join("user").<String>get("fullName"), "%" + userName + "%"));
}
if (phoneNumber.length() > 0) {
// Below line isn't working actually as join("UserPhone") - 'user' table has no reference for 'userPhone'. But 'userPhone' has 'user'.
predicates.add(criteriaBuilder.like(root.join("user").join("UserPhone").<String>get("phoneNumber"), "%" + postType + "%"));
}
return criteriaBuilder.and(predicates.toArray(new Predicate[predicates.size()]));
}
};
是的,如果我在'user'表中有'userPhone'引用,比如-product -> user -> userPhone
,而不是product -> user, userPhone -> user
,那就很容易了。但我的模式是这样的。现在,我很难加入这三个表并获取结果
# 1 楼答案
如果
cross-join
被占用而不是join
,你可以尝试这个解决方案