CODEWITHSUNDEEP
spring-bootjpapageable
dhS
dhS

Reputation: 3694

Pageable in spring for paging on List<Object> is not working

I have a list of object which contain 10000 records i am trying to split that records in each of 10,

But somehow it is not working.. can someone have a look

@Query("select a.applicantid,coalesce(to_char(a.createdon,'yyyy-MM-dd'),to_char(filing_date,'yyyy-MM-dd')) as dt1, \r\n" + 
        "coalesce(c.companyname,i.InstituteName,(u.firstname||' '||u.lastname),\r\n" + 
        "u.firstname) ,a.c_denomination,cc.crop_common_name,cs.crop_botanical_name,\r\n" + 
        "a.id,aps.status,a.cropid, \r\n" + 
        "(select mv.varietytype from VarietyType mv where mv.id= a.varirtytypeid),\r\n" + 
        "(select sv.subvarietytype from SubVarietyType sv,VarietyType mvr \r\n" + 
        " where a.subvarietytypeid = sv.id and mvr.id= sv.varietyid),a.formtype,mcg.crop_group \r\n" + 
        " from Applications a left join ApplicantRegistration ap on \r\n" + 
        " a.applicantid = ap.id left join CompanyRegistration c on ap.companyid = c.id \r\n" + 
        " left join InstitutionRegistration i on ap.institutionid = i.id \r\n" + 
        " left join Crops cc on a.cropid = cc.id left join CropSpecies cs \r\n" + 
        " on a.cropspeciesid =cs.id left join InternalUser u on ap.id = u.applicantid \r\n" + 
        " left join ApplicationStatus aps on a.application_current_status = aps.id "
        + "left join CropGroup mcg on cc.cropgroupid = mcg.id order by a.id desc")
       List<Object[]> getapplication_adminview();



List<Object[]> admin_viewapplication=applicationrepository.getapplication_adminview();
int pageNumber = 0;
int size = 10;
Pageable pageable = PageRequest.of(pageNumber, size); // object of pageable
Page<Object> pages = new PageImpl(admin_viewapplication, pageable, admin_viewapplication.size());
List<Object> lpage = pages.getContent(); // here i am getting the lpage size as 10000 but as i enter pageable as of size 10  i am expecting 10 results only

where i am going wrong in this ? if i am trying to add pagable object to query and run the code i will get the following error:

Cannot create TypedQuery for query with more than one return using requested result type [java.lang.Long]; nested exception is java.lang.IllegalArgumentException: Cannot create TypedQuery for query with more than one return using requested result type [java.lang.Long]

Upvotes: 0

Views: 8162

Answers (3)

Juan Ignacio Liska
Juan Ignacio Liska

Reputation: 179

the following tutorial helped me -> https://www.baeldung.com/spring-data-jpa-query

At this point 4.3. Spring Data JPA Versions Prior to 2.0.4

VERY IMPORTANT to add \ n-- #pageable \ n

Without this I was wrong

Also the pagination setting must be without ordering

PageRequest paginaConf = new PageRequest ((param1 - 1)
                                                 , param2);

Finally to convert the Page <Object []>

  Page <Object []> list = myQueryofRepo ();
         List <XXXModel> lstReturn = myConversor (list.getContent ());
         Page <XXXModel> ret = new PageImpl <XXXModel> (lstReturn, pageConf, param2);

Upvotes: 1

dhS
dhS

Reputation: 3694

We can use PagedListHolder which can change the list in pages and we can than fetch a page by setting it's page size and page.

PagedListHolder<Object> page = new PagedListHolder(admin_viewapplicationpage);
      page.setPageSize(50); // number of items per page
      page.setPage(0);      // set to first page

      int totalPages = page.getPageCount(); //  gives the totalpages according to the main list
      
      List<Object> admin_viewapplication = page.getPageList();  // a List which represents the current page which is the sublist

Upvotes: 1

Ken Chan
Ken Chan

Reputation: 90447

Page just represents one page of data . So page.getContent() only return all data in one page which is specified through constructor when you create this page instance . It has nothing to do with splitting the data in a page.

If you want to split a list , use Lists from Guava is the simplest way to go :

List<List<Object>> splittedList = Lists.partition(list, 10);

If you want to do pagination which split all the data stored in the database into different smaller pages , split it at the database level rather than getting the whole list to the memory to split which will be very inefficient when the entire list is large. See this for how to split it at the database level by declaring Pageable in the query method.

Upvotes: 1

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