i have a little problem with JPA criteria API. I have one Entity:
#Entity
#Table(name = "PERSON")
public class Person implements Serializable
{
#Id
#GeneratedValue(strategy=GenerationType.SEQUENCE, generator = "person_gen")
#Column(name = "ID")
private Long id;
#Column(name = "NAME")
private String name;
#Column(name = "AGE")
private Integer = age;
public Long getId()
{
return this.id;
}
public String getName()
{
return this.name;
}
public Integer getAge()
{
return this.age;
}
}
And now i want make a query similar to this:
select * from Person where
(Person.Id) in (select Person.Id from Person where Person.Id = 15625) or
(Person.Id) in (select Person.Id from Person where Person.Name = 'Name') or
(Person.Id) in (select Person.Id from Person where Person.Age = 28)
There are some subqueries with an 'or' statement. How to do this with JPA criteria query? I have tried many things an it does not work.
Thanks in advance.
Your particular query really is unnecessarily complex. Your IN predicates can all be removed and replaced by the following, much simpler predicates:
SELECT *
FROM Person
WHERE Id = 12625
OR Name = 'Name'
OR Age = 28
This should be much simpler to translate to a JPA criteria query.
Related
I want find a way to get extra column that count my records and return it in 1 mapping entity with extra filed.
I tried #transient on field but it will not return value when query.
Then I remove #transient but get an exception when save.
Also I tried #Formula but received null pointer exception.
Here's my repository code:
#Query(value = "select id,account,session_id,create_time,count from query_history a join " +
"(select session_id sessionId,max(create_time) createTime,count(*) count from query_history group by session_id) b " +
"on a.session_id = b.sessionId and a.create_time = b.createTime where account = ?1 order by create_time desc",
countQuery = "select count(distinct(session_id)) from query_history where account = ?1",
nativeQuery = true)
Page<QueryHistory> findByNtAndGroupBySessionAndAction(String account, Pageable pageable);
entity code:
#Entity
#Table(name = "query_history")
#Data
public class QueryHistory {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#Column
private String account;
#Column
private Long sessionId;
#Column
private long createTime;
#Transient
private Integer count;
}
Sorry about my English and thanks a lot for any advice.
I solved the problem by projections spring-data-projections, in fact I tried this before but in my sql:
select id,account,session_id,create_time,count
which should be:
select id,account,session_id sessionId,create_time createTime,count
PS:
projection interface:
public interface QueryHistoryWithCountProjection {
Long getId();
String getAccount();
Long getSessionId();
long getCreateTime();
Integer getCount();
}
Given this very simple DTO:
#Entity
public class Employee implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
private String name;
#OneToOne
private Employee boss;
}
I'd like to make a query that gathers all employee names and their boss' id, put in a nice clean POJO:
public class EmployeeInfo {
private String name;
private Long bossId;
public EmployeeInfo(String name, Long bossId) {
this.name = name;
this.bossId = bossId;
}
}
This query should be of use:
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<EmployeeInfo> query = cb.createQuery(EmployeeInfo.class);
Root<Employee> root = query.from(Employee.class);
query.select(
cb.construct(EmployeeInfo.class,
root.get("name").as(String.class),
root.get("boss").get("id").as(Long.class)));
result = em.createQuery(query).getResultList();
When a bossId is present in the employee column this works just fine. But when no boss id is set the record will be completly ignored. So how do i treat this non existing boss relation as null or 0 for the construct/multiselect?
In pure SQL it is easy:
SELECT name, COALESCE(boss_id, 0) FROM EMPLOYEE;
But for the love of god i cannot make the criteria api do this.
cb.construct(EmployeeInfo.class,
root.get("name").as(String.class),
cb.coalesce(root.get("boss").get("id").as(Long.class), 0L)));
The problem is that root.get("boss") generate query with cross join like this from Employee employee, Employee boss where employee.boss.id=boss.id. So records where employee.boss.id is null are ignored.
To solve the problem you should use root.join("boss", JoinType.LEFT) instead of root.get("boss")
I have problems creating the correct JPQL query for joining through the following tables:
While between GROUPS and USERS there is a conventional #ManyToMany mapping table, DOCUMENTS_GROUPS is what causes the trouble. As you can see in the following entity, I want the relationship between DOCUMENTS and GROUPS to be mapped as a Map containing the access_mode (which works just fine except for the query):
#Entity
#Table(name = "DOCUMENTS")
#NamedQueries({
#NamedQuery(
name = "Documents.findAccessibleByUser",
query = "SELECT d FROM Document d INNER JOIN d.groups g INNER JOIN KEY(g).members m WHERE m.id = :userId"
)
})
public class Document {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#ElementCollection
#CollectionTable(name = "DOCUMENTS_GROUPS", joinColumns = {#JoinColumn(name = "document_id")})
#MapKeyJoinColumn(name = "group_id")
#Column(name = "access_mode")
#Enumerated(EnumType.STRING)
private Map<Group, AccessMode> groups = new HashMap<>();
/* ... */
}
With Group being rather normal:
#Entity
#Table(name = "GROUPS")
public class Group {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#Column(length = 255)
private String name;
#ManyToMany
#JoinTable(name = "USERS_GROUPS", //
joinColumns = {#JoinColumn(name = "group_id")}, //
inverseJoinColumns = {#JoinColumn(name = "user_id")} //
)
private Set<User> members = new HashSet<>();
/* ... */
}
My question is now: How do I need to modify the second JOIN in my JPQL query?
SELECT d FROM Document d
INNER JOIN d.groups g
INNER JOIN KEY(g).members m
WHERE m.id = :userId
is syntactically wrong (unexpected KEY after INNER JOIN).
Of course, I have already tried a plain INNER JOIN g.members m, but since we're dealing with a Map<Group, AccessMode>, this fails with cannot dereference scalar collection element: members.
I was facing the same problem with a simple key-value Map<String, String> like:
#Entity Item.java
#ElementCollection
#MapKeyColumn(name = "name")
#Column(name = "value")
#CollectionTable(indexes = #Index(columnList = "value"))
private Map<String, String> attributes = new HashMap<>();
Joining the attributes was possible:
Query query = em.createQuery("SELECT i FROM Item i INNER JOIN i.attributes attr");
but not querying fields:
Query query = em.createQuery("SELECT i FROM Item i INNER JOIN i.attributes attr WHERE attr.value = 'something'");
I debugged the Hibernate internals and found out that the alias attr is already resolved to the value (e.attributes.value), so the only thing you can do here is:
Query query = em.createQuery("SELECT i FROM Item i INNER JOIN i.attributes attr WHERE attr = 'something'");
But I did not find any documentation or JPQL examples pointing that out. The behaviour is is useless in my case, because I want to have conditions for both key and value. Thats why I migrated to a foreign entity collection with key mapping and composite primary key. Its way more complicated but works as expected.
The composite key entity to prevent single primary keys
#Embeddable
public class ItemAttributeName implements Serializable {
private String name;
#ManyToOne
#JoinColumn(nullable = false)
private Item item;
// Empty default constructor is important
public ItemAttributeName() {
}
public ItemAttributeName(Item item, String name) {
this.item = article;
this.name = name;
}
}
The real attribute entity
#Entity
public class ItemAttribute {
#EmbeddedId
private ItemAttributeName id;
private String value;
// Empty default constructor is important
public ItemAttribute() {
}
public ItemAttribute(Item item, String name) {
this.id = new ItemAttributeName (item, name);
}
public String getValue() {
return value;
}
}
#Entity Item.java
#OneToMany(mappedBy = "id.item",cascade = CascadeType.PERSIST)
#MapKeyColumn(name = "name")
public Map<String, ItemAttribute> attributes = new HashMap<>();
Creating entities:
Item item = new Item ();
ItemAttribute fooAttribute = new ItemAttribute(item, "foo");
fooAttribute.setValue("356");
item.attributes.put("foo", fooAttribute);
Querying entities:
Query query = em.createQuery("SELECT i FROM Item i JOIN i.attributes attr WHERE attr.id.name = 'foo' AND attr.value='bar'");
List<Item> resultList = query.getResultList();
System.out.println(resultList.get(0).attributes.get("foo").getValue());
Prints out: bar
How to invoke order by on a joined entity? I am trying to achieve the following with:
select * from person p inner join telephone t on p.id=t.person_id join sim s on s.id=t.sim_id order by s.name DESC
#Entity
public class Person implements Serializable{
#Id
private Long id;
#OneToMany(orphanRemoval = true, mappedBy = "person", fetch = FetchType.LAZY, cascade = CascadeType.PERSIST)
private List<Telephone> telephonesNumber;
#Entity
public class Telephone implements Serializable {
#Id
private String number;
#Id
#ManyToOne()
#JoinColumn(name = "person_id")
private Person person;
#Id
#ManyToOne(cascade = {})
#JoinColumn(name = "sim_id")
private Sim sim;
#Entity
public class Sim implements Serializable {
#Id
private Long id;
#Column(unique = true)
private String name;
I use specification interface, in this example sorting is on the field person.id and it works
public class PersonSpecification implements Specification<Person> {
#Override
public Predicate toPredicate(Root<Person> root, CriteriaQuery<?> query, CriteriaBuilder builder) {
List<Predicate> predicates = new ArrayList<>();
// there is many different conditions for example
// if(someCondition!=null) {
// predicates.add(builder.like(root.get("someProperty"), someValue));
// }
query.groupBy(root.get("id"));
//there I want to order by Sim.name i dont know how
query.orderBy(builder.asc(root.get("phone")));//this works
return builder.and((predicates.toArray(new Predicate[predicates.size()])));
}
I want to order by Sim.name but i dont know how.
In JPA specification you can use:
query.orderBy(builder.asc(root.join("telephonesNumber").get("sim").get("name")));
to sort by sim name.
For more details:
https://en.wikibooks.org/wiki/Java_Persistence/Querying#Joining.2C_querying_on_a_OneToMany_relationship
If you using JPA Query:
#Query("select s from Person p
join p.telephonesNumber t
join t.sim s order
by t.sim.id desc")
It will produce this:
select * from person p
inner join telephone t on p.id=t.person_id
inner join sim s on t.sim_id=s.id
order by t.sim_id desc
For more details:
https://github.com/abhilekhsingh041992/spring-boot-samples/blob/master/jpa/src/main/java/example/springboot/jpa/repository/PersonRepository.java
another way for that would be using Query method:
List<Telephone> findAllByOrderBySimIdAsc();
Look at this findAllByOrderBySimIdAsc
With the code before, you can get all rows from Telephone ordered by Sim Id.
I have 2 Entity, Aluno and Matricula. I want return all Aluno without Matricula. To do this, I'm trying use IS NULL of JPQL but still could not do this work.
How can I do this ?
I'm trying this.
#Entity
public class Aluno{
#Id #GenerateValue
private Long id;
#OneToOne
private Matricula matricula
}
#Entity
public class Matricula{
#Id #GenerateValue
private Long id;
#OneToOne
private Aluno aluno;
}
//
public List<Aluno> getAlunosWithoutMatricula(){
String jpql = "SELECT a FROM Aluno a JOIN a.matricula mat WHERE mat IS NULL";
TypedQuery<Aluno> query = em.createQuery(jpql, Aluno.class);
return query.getResultList();
}
I solved the problem
here.
public List<Aluno> getAlunosWithoutMatricula(){
String jpql = "SELECT a FROM Aluno a WHERE (a.matricula IS NULL)";
TypedQuery<Aluno> query = em.createQuery(jpql, Aluno.class);
return query.getResultList();
}