Spring Data Combines with Features

Question

I am trying to convert this raw SQL query:

select product.* from following_relationship join product on following_relationship.following=product.owner_id where following_relationship.owner=input 

In the Spring Data Specification, I think my problem so far is to join these tables.

Here is my current conversion to Specification:

 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(); } }; } 

And I get this exception:

 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 

I would like to add that I am new to Spring framework, for example, this is my first spring application, so I apologize for the newbie question;)

Edit: added objects Product, nextRelationShip

 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; } } 

The product and the subsequent RelationShip entities do not have any explicit relationships, therefore, the union in my implementation is about. What I want to achieve is to get all products from all users who follow other users in the Spring data specifications.

Answer 1

EDITOR: Well, I'm quite a mess here, but hope this time I'm closer to the correct answer.

Consider (identifiers are automatically generated as 1 for John, etc.):

 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); 

Based on the simplified version of the entities you provided and SomeUser Entity, for example:

 @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>(); 

I created a spec like:

 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); } }; } 

And now, when we make a request like:

 SomeUser someUser = someUserRepository.findOne(Specifications.where(ProductSpecifications.userHasName("Kelly"))); List<Product> thatProducts = productRepository.findAll(Specifications.where(ProductSpecifications.joinTest(someUser))); System.out.println(thatProducts.toString()); 

We get:

 [Product [id=1, name=Nokia 3310], Product [id=4, name=Xiaomi MI5], Product [id=2, name=Sony Xperia Aqua]] 

And this, in my opinion, is equivalent to: "get all the products from all users to which another user is subject" - get the products of all users that Kelly adheres to.