I try to do the following inside a Spring Boot application : create a native query and page it so it can returns a page of a given number of elements from a #RestController.
Here's the snippet of my code, where em is the #PersistanceContext EntityManager, and the repository method is the following, knowing that queryString is the native query :
Query searchQuery = em.createNativeQuery(this.queryString, MyEntity.class);
List<MyEntity> resultsList = searchQuery.getResultList();
return new PageImpl<>(resultsList, PageRequest.of(index,size), resultsList.size());
My problem is that the Page returned has a content of the complete query result, not a content of the size of size parameter inside the PageRequest.of.
Has anybody faced the same issue and could give a working example on how to paginate a nativeQuery please ?
Thanks for your help
You are mixing Spring Data JPA (Pageable) with JPA EntityManager. You can't do that. If you are already using a native query then simply put the pagination in the query. You can use what your database supports, for example the standard:
SELECT [a_bunch_of_columns]
FROM dbo.[some_table]
ORDER BY [some_column_or_columns]
OFFSET #PageSize * (#PageNumber - 1) ROWS
FETCH NEXT #PageSize ROWS ONLY;
this is example of using native query with pagination:
#Query("SELECT c FROM Customer As c INNER JOIN Offer as f on f.id=c.specialOffer.id inner join User As u on u.id=f.user.id where u.id=?1 And c.status=?2")
Page<Customer> getAllCustomerToShop(Integer shopId,String status,Pageable pageable)
and then you can call it as:
getAllCustomerToShop(shopId,"status",PageRequest.of(index, PAGE_SIZE));
Modify your code as follows
Query searchQuery = em.createNativeQuery(this.queryString, MyEntity.class)
.setFirstResult(pageable.getPageNumber() * pageable.getPageSize())
.setMaxResults(pageable.getPageSize());
Related
Hi I use spring jpa to access my data in my spring boot project.I am wondering that is there any difference between #Query annatotation and critearia api in jpa.Are they totaly same or is there any difference(Their writing styles are different ,and I mean any performance or other issue between them)
Mostly I prefer #Query annotation it looks simple.Or any other option some one can advice like #Query or criteria api in spring jpa.And is there any disadvantages of #Query style?
#Query("SELECT u FROM User u WHERE u.status = 1")
Collection<User> findAllActiveUsers();
List<Book> findBooksByAuthorNameAndTitle(String authorName, String title) {
CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<Book> cq = cb.createQuery(Book.class);
Using #Query we can pass static query or pre compiled query so we can perform both select and non-select operations on the data
where as Criteria is suitable for executing Dynamic Queries such requirements occurs when data are know at run time
but using criteria api we can only perform select operations on the data.
For example
#Query(value = "SELECT u FROM User u")
List<User> findAllUsers(Sort sort);
We can also work with pre compiled query using #Query
For Example
#Query("SELECT u FROM User u WHERE u.status = :status and u.name = :name")
User findUserByStatusAndNameNamedParams(
#Param("status") Integer status,
#Param("name") String name);)
Dynamic queries like
Criteria cr = session.createCriteria(Employee.class);
// To get records having salary more than 2000
cr.add(Restrictions.gt("salary", 2000));
// To get records having salary less than 2000
cr.add(Restrictions.lt("salary", 2000));
Actual use of Dynamic queries comes when we'll encounter the need for building SQL statements based on conditions or data sets whose values are only known at runtime. And, in those cases, we can't just use a static query So we can't just use the #Query annotation since we can't provide a static SQL statement.In such case we use Criteria API
For more info follow the link provided
#Query and Criteria
I am trying to use Spring Data JPA Specificaiton to query data, but I got some problem here.
The Java code is as below:
List<NoticeEntity> studentNoticeEntityList = noticeRepository
.findAll((root, criteriaQuery, criteriaBuilder) -> {
criteriaQuery.distinct(true);
root.fetch(NoticeEntity_.contentEntitySet, JoinType.LEFT);
Predicate restrictions = criteriaBuilder.conjunction();
SetJoin<NoticeEntity, UserNoticeEntity> recipientNoticeJoin = root
.join(NoticeEntity_.recipientNoticeEntitySet, JoinType.INNER);
recipientNoticeJoin.on(criteriaBuilder.equal(
recipientNoticeJoin.get(UserNoticeEntity_.recipientStatus), NoticeRecipientStatus.Unread));
Join<UserNoticeEntity, WeChatUserEntity> recipientUserJoin = recipientNoticeJoin
.join(UserNoticeEntity_.user);
restrictions = criteriaBuilder.and(restrictions,
criteriaBuilder.equal(recipientUserJoin.get(WeChatUserEntity_.id), id));
// recipientNoticeJoin.fetch(UserNoticeEntity_.user, JoinType.INNER);
return restrictions;
});
When I comment the code "recipientNoticeJoin.fetch(UserNoticeEntity_.user, JoinType.INNER);", it is working fine, but when I un-comment this, I will get error:
org.hibernate.QueryException: query specified join fetching, but the owner of the fetched association was not present in the select list
So, I am wondering if join fetch is supported by using Specification way, or there is something wrong with my code.
I know there is another way by using #Query("some hql"), but somehow I just prefer to use the Specification way.
Thanks a lot.
The error specifies that you're missing an entity from your select list. Try this:
criteriaQuery.multiselect(root, root.get(NoticeEntity_.recipientNoticeEntitySet);
Also, hibernate may run a count query first to determine the number of results, and this can cause the above error. You can avoid this breaking by checking the return type of the query before adding the fetch.
Eager fetching in a Spring Specification
I am trying to fetch the employee details whose empltype is clerk and whose joining date is the recent one.
For which the query looks like following in SQL Server 2008:
select
*
from
employee jj
inner join
(
select
max(join_date) as jdate,
empltype as emptype
from
employee
where
empltype='clerk'
group by empltype
) mm
on jj.join_date=mm.jdate and jj.empltype=mm.emptype;
I am using SpringData JPA as my persistence layer using QuerylDSL,Specification and Predicate to fetch the data.
I am trying to convert the above query either in QueryDSL or Specification, but unable to hook them properly.
Employee Entity :
int seqid;(sequence id)
String empltype:
Date joindate;
String role;
Predicate method in Specifcation Class :
Predicate toPredicate(Root<employee> root,CriteriaQuery <?> query,CriteriaBuilder cb)
{
Predicate pred=null;
// Returning the rows matching the joining date
pred=cb.equal(root<Emplyoee_>.get("joindate"));
//**//
}
What piece of code should be written in //**// to convert about SQL query to JPA predicate. any other Spring Data JPA impl like #Query,NamedQuery or QueryDSL which returns Page also works for me.
Thanks in advance
I wrote this in notepad and it hasn't been tested but I think you're looking for something like
QEmployee e1 = new QEmployee("e1");
QEmployee e2 = new QEmployee("e2");
PathBuilder<Object[]> eAlias = new PathBuilder<Object[]>(Object[].class, "eAlias");
JPASubQuery subQuery = JPASubQuery().from(e2)
.groupBy(e2.empltype)
.where(e2.empltype.eq('clerk'))
.list(e2.join_date.max().as("jdate"), e2.emptype)
jpaQuery.from(e1)
.innerJoin(subQuery, eAlias)
.on(e1.join_date.eq(eAlias.get("jdate")), e1.emptype.eq(eAlias.get("emptype")))
.list(qEmployee);
I'm using the Spring PageRequest to sort (order) a custom query by a column in my database.
If I'm doing a custom query such as :
#Query( value = "select h from hunterhouse h join h.queens q where q.name = 'Computer Science'")
Is it not possible to sort by a column in q, the table I am joining to?
PageRequest request = new PageRequest(page, size, Sort.Direction.DESC, "q.region");
debug comes out as "order by h.q.region" which is incorrect, is it not possible to order by a join column?
You simply put the complete path you want to join on into the sort expression. So what you'd need to use is queens.region which will then be translated into h.queens.region and appended to the JPQL query you defined.
I had the same problem! This bug was fixed in Spring Data JPA 1.7.3 - just make sure you have a version higher or equal to 1.7.3! After that it will work with queens.region
Spring source: https://jira.spring.io/browse/DATAJPA-726
I am new to spring JPA . I have one query such that i've to get the resultset and take only the row at the top.I dont know how to do it in spring JPA.And i dont want it to be done using #Query annotation,Since i was asked not to go with any queries inside the code.This is the uery i want to convert
My Query
SELECT id,name FROM example_table ORDER BY id DESC LIMIT 1;
I tried something like this in my predicate file:
public Predicate getLatest(){
QExampleTable example = QExampleTable.exampleTable;
return (Predicate) example.id.desc();
}
and this is how my jpa repository looks like:
public ExampleTable findOne(MyPredicate.getLatest());
But this is'nt working out and i know it wont clearly.But I seriously dont know how to convert this above query.Can anyone help me out with this
You can do it using just QueryDSL without Predicate and Repositories.
List<ExampleTable> examples = new JPAQuery()
.from(QExampleTable.exampleTable)
.limit(1)
.orderBy(new OrderSpecifier<>(Order.DESC, QExampleTable.exampleTable.id))
.list(QExampleTable.exampleTable);
you can use offset or limit functions.
In your case .limit(1) should be enough
This won't work because desc() returns an OrderSpecifier that must be used with Query.orderBy().
The following could work, though it's not a "pure" Predicate:
public Predicate getLatest() {
QExampleTable example = QExampleTable.exampleTable;
return example.id.eq(new JPASubQuery().from(example).unique(example.id.max()));
}
I'm afraid a more clean solution is that you provide a CustomRepository + implementation.
With QueryDSL for me, the option that is working is using max().
JPAExpressions.selectFrom(QExampleTable.exampleTable)
.select(QExampleTable.exampleTable.max())