Spring Data Join 规范
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【中文标题】Spring Data Join 规范【英文标题】：Spring Data Join with Specifications 【发布时间】：2016-11-05 04:55:59 【问题描述】：我正在尝试转换这个原始 sql 查询：
select product.* from following_relationship
join product on following_relationship.following=product.owner_id
where following_relationship.owner=input
在 Spring Data 规范中，我认为到目前为止我的问题在于加入这些表。
这是我目前在规范中的转换：
protected Specification<Product> test(final User user)
return new Specification<Product>()
@Override
public Predicate toPredicate(Root<Product> root, CriteriaQuery<?> query, CriteriaBuilder cb)
Join<FollowingRelationship,Product> pfJoin = query.from(FollowingRelationship.class).join("following");
pfJoin.on(cb.equal(pfJoin.get("following"),"owner"));
return query.where(cb.equal(pfJoin.get("following"),user)).getGroupRestriction();
;
我得到了这个例外：
Request processing failed; nested exception is org.springframework.dao.InvalidDataAccessA
piUsageException: org.hibernate.hql.internal.ast.InvalidWithClauseException: with clause can only reference columns in the driving table
我想补充一点，我是 Spring 框架的新手，例如这是我在 Spring 上的第一个应用程序，所以对于新手问题我深表歉意 ;)
编辑：添加实体 Product、FollowingRelationShip
Entity
@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "json_id_prop")
public class FollowingRelationship extends BaseEntity
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "OWNER", referencedColumnName = "uuid")
private User owner;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "FOLLOWING", referencedColumnName = "uuid")
private User following;
public User getOwner()
return owner;
public void setOwner(User owner)
this.owner = owner;
public User getFollowing()
return following;
public void setFollowing(User following)
this.following = following;
@Entity
@Table(name = "product")
@JsonIdentityInfo(generator = ObjectIdGenerators.IntSequenceGenerator.class, property = "json_id_prop")
public class Product extends BaseEntity
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "OWNER_ID", referencedColumnName = "uuid")
private User owner;
@NotNull
private String name;
@NotNull
private String description;
@NotNull
private String price;
@NotNull
private String brand;
public String getName()
return name;
public void setName(String name)
this.name = name;
public String getDescription()
return description;
public void setDescription(String description)
this.description = description;
public String getPrice()
return price;
public void setPrice(String price)
this.price = price;
public String getBrand()
return brand;
public void setBrand(String brand)
this.brand = brand;
public User getOwner()
return owner;
public void setOwner(User owner)
this.owner = owner;
Product 和 FollowRelationShip 实体没有任何明确的关系，因此加入我的实现 about。我想要实现的是从 Spring 数据规范中另一个用户遵循的所有用户获取所有产品。
【问题讨论】：
应该pfJoin.on(cb.equal(pfJoin.get("following"),"owner")); 是pfJoin.on(cb.equal(pfJoin.get("following"),"owner_id")); 吗？
编辑：好的，我在这里做得很乱，但我希望这次我更接近正确答案。
考虑（ID 是自动生成的，例如 John 等的 1）：
INSERT INTO some_user (name) VALUES ('John');
INSERT INTO some_user (name) VALUES ('Ariel');
INSERT INTO some_user (name) VALUES ('Brian');
INSERT INTO some_user (name) VALUES ('Kelly');
INSERT INTO some_user (name) VALUES ('Tom');
INSERT INTO some_user (name) VALUES ('Sonya');
INSERT INTO product (owner_id,name) VALUES (1,'Nokia 3310');
INSERT INTO product (owner_id,name) VALUES (2,'Sony Xperia Aqua');
INSERT INTO product (owner_id,name) VALUES (3,'IPhone 4S');
INSERT INTO product (owner_id,name) VALUES (1,'Xiaomi MI5');
INSERT INTO product (owner_id,name) VALUES (3,'Samsung Galaxy S7');
INSERT INTO product (owner_id,name) VALUES (3,'Sony Xperia Z3');
INSERT INTO following_relationship (follower_id, owner_id) VALUES (4,1);
INSERT INTO following_relationship (follower_id, owner_id) VALUES (5,1);
INSERT INTO following_relationship (follower_id, owner_id) VALUES (4,2);
INSERT INTO following_relationship (follower_id, owner_id) VALUES (6,2);
INSERT INTO following_relationship (follower_id, owner_id) VALUES (6,3);
INSERT INTO following_relationship (follower_id, owner_id) VALUES (1,3);
基于您提供的实体的简化版本，以及 SomeUser 实体，例如：
@Entity
public class FollowingRelationship
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Long id;
@ManyToOne(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
@JoinColumn(name = "owner_id")
SomeUser owner;
@ManyToOne(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
@JoinColumn(name = "follower_id")
SomeUser follower;
...
@Entity
public class Product
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Long id;
@ManyToOne()
@JoinColumn(name = "owner_id")
private SomeUser owner;
@Column
private String name;
...
@Entity
public class SomeUser
@Id
@GeneratedValue(strategy=GenerationType.IDENTITY)
private Long id;
@Column
private String name;
@OneToMany(mappedBy = "owner")
private Set<Product> products = new HashSet<Product>();
@OneToMany(mappedBy = "owner")
private Set<FollowingRelationship> ownedRelationships = new HashSet<FollowingRelationship>();
@OneToMany(mappedBy = "follower")
private Set<FollowingRelationship> followedRelationships = new HashSet<FollowingRelationship>();
我创建了如下规范：
public static Specification<Product> joinTest(SomeUser input)
return new Specification<Product>()
public Predicate toPredicate(Root<Product> root, CriteriaQuery<?> query, CriteriaBuilder cb)
Join<Product,SomeUser> userProd = root.join("owner");
Join<FollowingRelationship,Product> prodRelation = userProd.join("ownedRelationships");
return cb.equal(prodRelation.get("follower"), input);
;
现在，我们可以执行查询：
SomeUser someUser = someUserRepository.findOne(Specification.where(ProductSpecifications.userHasName("Kelly")));
List<Product> thatProducts = productRepository.findAll(Specification.where(ProductSpecifications.joinTest(someUser)));
System.out.println(thatProducts.toString());
我们得到：
[Product [id=1, name=Nokia 3310], Product [id=4, name=Xiaomi MI5], Product [id=2, name=Sony Xperia Aqua]]
在我看来，这相当于：“获取其他用户关注的所有用户的所有产品”- 获取 Kelly 关注的所有用户的产品。
【讨论】：
谢谢，我一回到家就会这样做。请 Product 和 FollowRelationship 没有任何关系，它们唯一的共同点是用户，因此每个产品都有它的所有者（用户），其中 FollowRelationship 具有以下字段和关注者字段（它们都是用户类型或实体）。因此，我试图获取其他特定用户正在关注的所有用户的所有产品。 这就是为什么我需要在 FollowRelationship 实体中加入产品实体的原因，其中 FollowRelationship.following = product.owner 好的，我会改写答案，但请在你回家后给我看实体。当你现在解释的时候我明白了基本的想法，但是当我看到它时会容易得多。 Helle @patrykos91 你有机会看看我更新的帖子吗？以上是关于Spring Data Join 规范的主要内容，如果未能解决你的问题，请参考以下文章
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