I have two entities, Movie and Genre, with a many to many relationship from genre to movie. Genre being the "parent" of the relationship.
This generates three tables: genre, movie and genre_movie
#Entity
public class Genre {
#Id
#GeneratedValue(strategy = AUTO)
private Long id;
#ManyToMany(fetch = LAZY)
#JoinTable( name = "genre_movie",
joinColumns = {#JoinColumn(name = "genre_id")},
inverseJoinColumns = {#JoinColumn(name = "movie_id")}
)
private Set<Movie> movies = new HashSet<>();
...
}
#Entity
public class Movie {
#Id
#GeneratedValue(strategy = AUTO)
private Long id;
...
}
I it possible perform this query using the criteria query api? Filter movies based on their genre id.
select *
from movie
join genre_movie on movie.id = genre_movie.movie_id
where genre_id = 19;
It is not possible because the Movie entity does not have a reference to Genre as it is not bidirectional.
But you can restructure the query to get the same results:
Select * from genre
inner join genre_movie on genre.id = genre_movie.genre_id
inner join movie on genre_movie.movie_id = movie.id
where genre.genre_id = 19;
The query would be implemented as follows:
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<Movie> cq = cb.createQuery(Movie.class);
Root<Genre> rootGenre = cq.from(Genre.class);
Join<Genre,Movie> joinMovie = rootGenre.join("movies");
//Join<Genre,Movie> joinMovie = rootGenre.join(Genre_.movies);
cq.select(joinMovie);
cq.where(cb.equals(rootGenre.get("id"), 19));
//cq.where(cb.equals(rootGenre.get(Genre_.id), 19));
return this.em.createQuery(cq).getResultList();
I particularly recommend using metamodels (commented lines) since when accessing the properties by name in String format, errors can occur that with Metamodels not in more complex queries.
I also think it would be interesting to define the relationship as bidirectional to be able to set the Movie class as Root
Related
Hello This is my 2 tables:
record and submission.
In submission, it has 1 composite primary key:(submission_id, question_id). One submission number can have several questions number. For example:
And as for record, it has a composite primary key:(student_id, exam_id). It looks like this:
I want to join these 2 tables like MySQL:
select * from record
left join submission
on record.submission_id = submission.submission_id.
But in hibernate, I have successfully join these 2 tables, but it gives me the following hql:
Hibernate:
select
...all columns...
from
record record0_
inner join
submission submission1_
on record0_.submission_id=submission1_.submission_id
and record0_.question_id=submission1_.question_id
where
1=1
In this case, I will get 0 rows in the result.
I don't want it use "and record0_.question_id=submission1_.question_id" after on clause, because there is no question_id in my record table.
But I have to add all primary keys into the #joinColumns() when I add Submission attribute in Record class, like this:
// Record class
#Getter
#Setter
#ToString
#AllArgsConstructor
#NoArgsConstructor
#Entity
#Table(name = "record")
public class Record implements java.io.Serializable{
private static final long serialVersionUID = 1L;
// Other columns I don't need to show
#Column(name = "submission_id")
private Integer submissionId;
#OneToOne(fetch = FetchType.LAZY)
#JoinColumns({
#JoinColumn(name = "submission_id", referencedColumnName = "submission_id",insertable=false, updatable=false),
#JoinColumn(name = "question_id", referencedColumnName = "question_id",insertable=false, updatable=false)
})
private Submission submission;
}
My Submission class like this:
#Getter
#Setter
#ToString
#AllArgsConstructor
#NoArgsConstructor
#Entity
#Table(name = "submission")
public class Submission implements java.io.Serializable{
private static final long serialVersionUID = 1L;
#Id
#Column(name = "submission_id")
private Integer submissionId;
#Id
#Column(name = "question_id")
private Integer questionId;
#OneToOne(fetch = FetchType.LAZY, mappedBy = "submission")
private Record record;
}
Anyone can give me some advice?
-------- How I combine these tables-------
Actually, I join 4 tables and all these joins have the same problem declared above.
Code below is how i combine these 4 tables (record, submission, question, optional)
#Override
public List<RcdSubQuesOpt> getRcdSubQuesOpt(int studentID, int examId) {
Session session = this.getSession();
// RcdSubQuesOpt --> this is a class to store attributes from different tables(classes)
List<RcdSubQuesOpt> results;
Transaction transaction = null;
transaction = session.beginTransaction();
CriteriaBuilder criteriaBuilder = session.getCriteriaBuilder();
CriteriaQuery<RcdSubQuesOpt> criteriaQuery = criteriaBuilder.createQuery(RcdSubQuesOpt.class);
// To combine these tables use join
Root<Record> pRoot = criteriaQuery.from(Record.class);
Join<Record, Submission> rcd2sub = pRoot.join(Record_.submission);
Join<Submission, Question> sub2que = rcd2sub.join(Submission_.question);
Join<Question, Optional> que2opt = sub2que.join(Question_.optional);
// Attributes in RcdSubQuesOpt class
// get these columns from result and assign them to RcdSubQuesOpt class
criteriaQuery.multiselect(
pRoot.get("studentId"),
pRoot.get("examId"),
rcd2sub.get("questionId"),
rcd2sub.get("stuAnswer"),
sub2que.get("content"),
que2opt.get("content"),
que2opt.get("answer"));
// Predicate predicate = pRoot.get("examId").equals(1);
criteriaQuery.where();
results = session.createQuery(criteriaQuery).getResultList();
transaction.commit();
return results;
}
You haven't mentioned how you retrieve that data using hibernate. Have you tried trying to use #Query (select r from Record left join Submission sub on r.submissionId = sub.id where ...") ?
you have defined a #OneToOne relation in your record class. Apparantly thats wrong, since there exists more then one entry in your submission table for one record. So change this to #OneToMany and the respective relation in the submission class to #ManyToOne.
Besides your entities are not well named and mapped. Submission is in fact more of a question or an answer to it, because a line in that table does not represent one submission, which would be the expected meaning.
I'm trying to lazily load the ingredients of a product in a self relationship. A product can have zero or more ingredients. The relationship is stored in the ProductComposition entity.
These are my entities:
Product
#Entity(name = Product.TABLE_NAME)
//#NamedEntityGraph(name = "graph.Product.ingredients", attributeNodes = //#NamedAttributeNode("ingredients"))
public class Product {
public static final String TABLE_NAME = "Product";
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long idProduct;
private String name;
#OneToMany(fetch = FetchType.EAGER, cascade = {CascadeType.MERGE}, mappedBy = "product")
private List<OrderDetail> orders;
#OneToMany(fetch = FetchType.LAZY,cascade = CascadeType.ALL, mappedBy = "ingredient", orphanRemoval=true)
private List<ProductComposition> ingredients;
ProductComposition
#Entity(name = ProductComposition.TABLE_NAME)
#IdClass(ProductCompositionId.class)
public class ProductComposition {
public static final String TABLE_NAME = "ProductComposition";
#Id
#ManyToOne //(fetch = FetchType.LAZY)
#PrimaryKeyJoinColumn(name = "PrincipalProductID")
private Product principalProduct;
#Id
#ManyToOne //(fetch = FetchType.LAZY)
#PrimaryKeyJoinColumn(name = "IngredientID")
private Product ingredient;
private int quantity;
ProductCompositionId
class ProductCompositionId implements Serializable{
private long principalProduct;
private long ingredient;
In the method get of my Dao I've tried different things:
Fetching with a CriteriaQuery the ingredients and then set them to the product
CriteriaBuilder cb = entityManager.getCriteriaBuilder();
CriteriaQuery<ProductComposition> q = cb.createQuery(ProductComposition.class);
Root<ProductComposition> product = q.from(ProductComposition.class);
product.fetch("principalProduct", JoinType.LEFT);
q.select(product).where(cb.equal(product.get("principalProduct"), id));
List<ProductComposition> ingredients = entityManager.createQuery(q).getResultList();
Product p = entityManager.find(Product.class, id);
p.setIngredients(ingredients);
Using an Entity Graph
EntityGraph<Product> graph = (EntityGraph<Product>) entityManager.getEntityGraph("graph.Product.ingredients");
Map<String, Object> ingredients = new HashMap<>();
ingredients.put("javax.persistence.fetchgraph", graph);
Product p = entityManager.find(entityClass, id, ingredients);
Calling the method initialize
p = productDao.get(p.getIdProduct()); //the get here just calls entityManager.find(Product.class, id)
Hibernate.initialize(p.getIngredients());
System.out.println("Ingredients size: "+p.getIngredients().size()); //gives 0
After calling those two above lines I get the following two logs, but p still has no ingredients after:
Hibernate: select product0_.idProduct as idProduc1_4_0_, product0_.name as name2_4_0_, orders1_.product_idProduct as product_3_3_1_, orders1_.foodOrder_idFoodOrder as foodOrde2_3_1_, orders1_.foodOrder_idFoodOrder as foodOrde2_3_2_, orders1_.product_idProduct as product_3_3_2_, orders1_.quantity as quantity1_3_2_, foodorder2_.idFoodOrder as idFoodOr1_2_3_, foodorder2_.CustomerID as Customer2_2_3_, foodorder2_.DeliverymanID as Delivery3_2_3_, foodorder2_.RestaurantID as Restaura4_2_3_ from Product product0_ left outer join OrderDetail orders1_ on product0_.idProduct=orders1_.product_idProduct left outer join FoodOrder foodorder2_ on orders1_.foodOrder_idFoodOrder=foodorder2_.idFoodOrder where product0_.idProduct=?
Hibernate: select ingredient0_.ingredient_idProduct as ingredie2_5_0_, ingredient0_.principalProduct_idProduct as principa3_5_0_, ingredient0_.ingredient_idProduct as ingredie2_5_1_, ingredient0_.principalProduct_idProduct as principa3_5_1_, ingredient0_.quantity as quantity1_5_1_, product1_.idProduct as idProduc1_4_2_, product1_.name as name2_4_2_ from ProductComposition ingredient0_ inner join Product product1_ on ingredient0_.principalProduct_idProduct=product1_.idProduct where ingredient0_.ingredient_idProduct=?
However, all tries can't load the ingredients. They just return an empty list.
What am I doing wrong in this methods?
I would prefer to keep the relationship as lazy. Also because otherwise hibernate will return cannot simultaneously fetch multiple bags referring to Product.orders and Product.ingredients
This is my Entity configuration
#Entity
#NamedQuery(name = "Payment.findByEmail", query = "SELECT p FROM Payment p JOIN p.additionalAuthData a " +
"WHERE KEY(a) = 'email' AND VALUE(a) = ?1 AND (p.paymentType = 4 OR p.paymentType = 10)")
public class Payment {
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
private Long id;
#Column(name = "payment_type")
private Integer paymentType;
/** other properties, getters and setters */
#ElementCollection
#CollectionTable(name = "additional_auth_data")
#MapKeyJoinColumn(name = "id", referencedColumnName = "id")
#MapKeyColumn(name = "field")
#Column(name = "data_value")
private Map<String, String> additionalAuthData;
}
The NamedQuery findByEmail("test#example.com") generates the following SQL
select -- all fields ...
from payment payment0_ inner join additional_auth_data additional1_ on payment0_.id=additional1_.id
where
additional1_.field='email' and (select additional1_.data_value from additional_auth_data additional1_ where payment0_.id=additional1_.id)='test#example.com' and (payment0_.payment_type=4 or payment0_.payment_type=10)
which is wrong: it may work if you have only one row but it blows up otherwise. H2 complains Scalar subquery contains more than one row and PostgreSQL more than one row returned by a subquery used as an expression. In fact, query's where condition compares a scalar value ('test#example.com') with a subquery.
The correct SQL should be:
select -- all fields
from payment payment0_ inner join additional_auth_data additional1_ on payment0_.id=additional1_.id
where additional1_.field='payerEmail' and additional1_.data_value='test#example.com' and (payment0_.payment_type=4 or payment0_.payment_type=10)
Is the HSQL correct? Is there a way to instruct Hibernate to generates a clever, better SQL? Is this a Hibernate bug?
Note: Hibernate shipped with Spring Boot Starter 1.3.7.RELEASE
Edit:
Using an #Embeddable class
#ElementCollection
#JoinTable(name = "additional_auth_data", joinColumns = #JoinColumn(name = "id"))
#MapKeyColumn(name = "field")
#Column(name = "data_value")
private Set<AdditionalData> additionalAuthData;
#Embeddable
public static class AdditionalData {
#Column(name = "field", nullable = false)
private String field;
#Column(name = "data_value")
private String dataValue;
protected AdditionalData() {
}
public AdditionalData(String field, String dataValue) {
this.field = field;
this.dataValue = dataValue;
}
/** Getters, setters; equals and hashCode on "field" */
}
#NamedQuery(name = "Payment.findByEmail", query = "SELECT p FROM Payment p JOIN p.additionalAuthData a " +
"WHERE a.field = 'email' AND a.dataValue = ?1 AND (p.paymentType = 4 OR p.paymentType = 10)")
solves the problem, and the SQL is correct, but it looks just plain wrong, like shooting a fly with a bazooka...
It generates correct SQL without value().
Use just a=?1
But I would expect is should generate it simple also with it.
I am building a messaging system for my web application using Spring MVC with Spring Data JPA and Hibernate as my JPA provider.
I have five entities: Thread, ThreadParticipant, Participant, Account and Company. Each message thread has at least two participants, one of which is associated with a user (Account entity), and the other is associated with a Company. This constraint is enforced by the application. The database is designed like this to support future features. An example of two participants for a given thread in the database looks as follows:
id account_id company_id
1 44 NULL
2 NULL 123
The row with id=1 is the user, and the row with id=2 is the company. What I want to do is to write an HQL query that extracts all Thread objects for a given account, containing both the user/account participant as well as the company participant. I have tried to use different alias for my joins, like this:
select distinct t
from Thread t
inner join fetch t.threadParticipants user_tp
inner join fetch t.threadParticipants company_tp
inner join fetch user_tp.participant user_p
inner join fetch user_p.account a
inner join fetch company_tp.participant receiver_p
inner join fetch receiver_p.company
where a.id = :accountId
I get the exception cannot simultaneously fetch multiple bags due to the two fetches of t.threadParticipants. If I only do a single join here, the generated SQL simply ignores my additional join and only joins to Participant once, which requires a participant to have both an account and a company associated. With raw SQL, I can do like this, and it works fine:
select *
from thread t
inner join thread_participant user_tp on (user_tp.thread_id = t.id)
inner join thread_participant company_tp on (company_tp.thread_id = t.id)
inner join participant user_p on (user_p.id = user_tp.participant_id)
inner join account a on (a.id = user_p.account_id)
inner join participant company_p on (company_p.id = company_tp.participant_id)
inner join company c on (c.id = company_p.company_id)
where a.id = 123;
If I don't use different alias for the same table (see the below query), the query runs fine, but I only get one of the thread participants returned - the one that is associated with the account.
select distinct t
from Thread t
inner join fetch t.threadParticipants tp
inner join fetch tp.participant p
inner join fetch p.account a
left join fetch p.company
where a.id = :accountId
Is there any way that I can do what I am trying to do with HQL, or do I have to go with using native SQL?
My mapping is as follows:
Thread entity
#Entity
#Table(name = "thread")
public class Thread {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column
private int id;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "thread", cascade = { CascadeType.PERSIST, CascadeType.MERGE })
private Collection<ThreadParticipant> threadParticipants = new HashSet<>();
// Getters and setters
}
Participant entity
#Entity
#Table(name = "participant")
public class Participant {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column
private int id;
#ManyToOne(fetch = FetchType.LAZY, optional = true, targetEntity = Account.class, cascade = { CascadeType.PERSIST })
#JoinColumn(name = "account_id")
private Account account;
#ManyToOne(fetch = FetchType.LAZY, optional = true, targetEntity = Company.class)
#JoinColumn(name = "company_id")
private Company company;
// Getters and setters
}
ThreadParticipant entity
#Entity
#Table(name = "thread_participant")
#IdClass(ThreadParticipantPK.class)
public class ThreadParticipant implements Serializable {
#Id
#ManyToOne(fetch = FetchType.LAZY, targetEntity = Participant.class, cascade = { CascadeType.PERSIST, CascadeType.MERGE })
#JoinColumn(name = "participant_id")
private Participant participant;
#Id
#ManyToOne(fetch = FetchType.LAZY, targetEntity = Thread.class)
#JoinColumn(name = "thread_id")
private Thread thread;
#Column(name = "last_viewed", nullable = true)
private Date lastViewed;
// Getters and setters
}
ThreadParticipantPK
public class ThreadParticipantPK implements Serializable {
private Thread thread;
private Participant participant;
public ThreadParticipantPK() { }
public ThreadParticipantPK(Thread thread, Participant participant) {
this.thread = thread;
this.participant = participant;
}
#Override
public boolean equals(Object o) {
if (this == o) return true;
if (!(o instanceof ThreadParticipantPK)) return false;
ThreadParticipantPK that = (ThreadParticipantPK) o;
if (!participant.equals(that.participant)) return false;
if (!thread.equals(that.thread)) return false;
return true;
}
#Override
public int hashCode() {
int result = thread.hashCode();
result = 31 * result + participant.hashCode();
return result;
}
// Getters and setters
}
Thank you in advance!
Try changing the type of the threadParticipants collection to Set instead of a Collection:
private Set<ThreadParticipant> threadParticipants;
I have got two entities Person and Book. Only one instance of a specific book is stored to the system (When a book is added, application checks if that book is already found before adding a new row to the database). Relevant source code of the entities is can be found below:
#Entity
#Table(name="persons")
#SequenceGenerator(name="id_sequence", sequenceName="hibernate_sequence")
public class Person extends BaseModel
{
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_sequence")
private Long id = null;
#ManyToMany(targetEntity=Book.class)
#JoinTable(name="persons_books", joinColumns = #JoinColumn( name="person_id"), inverseJoinColumns = #JoinColumn( name="book_id"))
private List<Book> ownedBooks = new ArrayList<Book>();
}
#Entity
#Table(name="books")
#SequenceGenerator(name="id_sequence", sequenceName="hibernate_sequence")
public class Book extends BaseModel
{
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "id_sequence")
private Long id = null;
#Column(name="name")
private String name = null;
}
My problem is that I want to find persons, which are owning some of the books owned by a specific person. The returned list of persons should be ordered by using following logic: The person owning most of the same books should be at the first of the list, second person of the the list does not own as many books as the first person, but more than the third person. The code of the method performing this query is added below:
#Override
public List<Person> searchPersonsWithSimilarBooks(Long[] bookIds) {
Criteria similarPersonCriteria = this.getSession().createCriteria(Person.class);
similarPersonCriteria.add(Restrictions.in("ownedBooks.id", bookIds));
//How to set the ordering?
similarPersonCriteria.addOrder(null);
return similarPersonCriteria.list();
}
My question is that can this be done by using Hibernate? And if so, how it can be done? I know I could implement a Comparator, but I would prefer using Hibernate to solve this problem.
When using SQL the result I want can be achieved by using following SQL query:
select p.name, count(p.name) as bookCount from persons p, books b, person_book pb
where pb.person_id = p.id and pb.book_id = b.id and b.id in (1,2,3,4,5,6) group by
name order by bookCount desc
I have been trying to figure out how to translate this into the Criteria query. I have been trying to use Projections, but i seem to be unable to map the results back to the Person object.
Is this of any use?
http://docs.jboss.org/hibernate/core/3.3/reference/en/html/querycriteria.html#querycriteria-ordering
I finally managed to solve this problem. The following method works as expected:
#Override
public List<Person> searchPersonsWithSimilarBooks(Long[] bookIds) {
Criteria similarPersonCriteria = this.getSession().createCriteria(Person.class, "p");
Criteria bookCriteria = similarPersonCriteria.createCriteria("ownedBooks", "b");
bookCriteria.add(Restrictions.in("b.id", bookIds));
similarPersonCriteria.setProjection(Projections.projectionList()
.add(Projections.groupProperty("p.id"), "id")
.add(Projections.rowCount(), "similarBookCount"));
similarPersonCriteria.addOrder(Order.desc("similarBookCount"));
similarPersonCriteria.setResultTransformer(new AliasToBeanResultTransformer(Person.class));
return similarPersonCriteria.list();
}
I also updated my person class by adding a transient property called similarBookCount, which can be useful in some situations.