Returning Page<Object> in Query DSL - spring

Question

I am using Query DSL and want my result set to return a Page Object. Is there a way to do that in Query DSL? If so Whats my query going to be looking like?
I am using JPAQuery and I have my QClasses
The Method structure is this
public Page<Object> searchPerson(String name,String phone){
Page<Object> results=null;
JPQLQuery query = new JPAQuery(entityManager);
QPerson person = QPerson.person;
//I am assuming my query would go here
results = query.from(person). ?????
return results;}
Help!

Answer 1

Here is my implementation for Paging with QueryDSL. A PageRequest defines the parameters for our query (limit and page):
public class PageRequest {
protected Long page = 1l;// 1 is the first page
protected Integer limit = 10;
public PageRequest(Long page, Integer limit) {
this.limit = limit;
this.page = page;
}
public Long getPage() {
return page;
}
public Integer getLimit() {
return limit;
}
public Long getOffset() {
return (page - 1l) * limit;
}
}
The Page Class contains the result (here the attribute objects) of the query and could implement methods to create nice paging links.
public class Page<T> extends PageRequest {
protected Collection<T> objects;
private Long totalCount;
private Long pageCount;
private Boolean hasPageLinkPrev;
private Boolean hasPageLinkNext;
private Collection<Long> pageLinks;
public Page(Long page, Integer limit, Long totalCount, Collection<T> objects) {
this.page = page;
this.limit = limit;
this.totalCount = totalCount;
this.objects = objects;
this.pageCount = totalCount / limit;
if (totalCount % limit > 0) {
this.pageCount = this.pageCount + 1;
}
this.hasPageLinkPrev = page > 1;
this.hasPageLinkNext = page < this.pageCount;
this.pageLinks = new ArrayList<>();
if (this.pageCount != 1) {
this.pageLinks.add(1l);
if (page > 3l) {
this.pageLinks.add(-1l);
}
if (page > 2l) {
if (page.equals(this.pageCount) && this.pageCount > 3l) {
this.pageLinks.add(page - 2l);
}
this.pageLinks.add(page - 1l);
}
if (page != 1l && !page.equals(this.pageCount)) {
this.pageLinks.add(page);
}
if (page < this.pageCount - 1l) {
this.pageLinks.add(page + 1l);
if (page == 1l && this.pageCount > 3l) {
this.pageLinks.add(page + 2l);
}
}
if (page < this.pageCount - 2l) {
this.pageLinks.add(-1l);
}
this.pageLinks.add(this.pageCount);
}
}
public Page(PageRequest pageRequest, Long totalCount, Collection<T> objects) {
this(pageRequest.getPage(), pageRequest.getLimit(), totalCount, objects);
}
public Long getTotalCount() {
return this.totalCount;
}
public Long getPageCount() {
return this.pageCount;
}
public Long getPage() {
return this.page;
}
public Integer getLimit() {
return this.limit;
}
public Boolean getHasPageLinkPrev() {
return this.hasPageLinkPrev;
}
public Boolean getHasPageLinkNext() {
return hasPageLinkNext;
}
public Collection<Long> getPageLinks() {
return pageLinks;
}
public Collection<T> getObjects() {
return objects;
}
}
With that stuf it is not very hard to create the query and put the results in our page object. One possibility is to write a generic method in the base class of the repository classes:
protected <T> Page<T> getPage(JPQLQuery<T> query, PageRequest pageRequest) {
List<T> resultList = query
.offset(pageRequest.getOffset())
.limit(pageRequest.getLimit())
.fetch();
Long totalCount = query.fetchCount();
return new Page<T>(pageRequest, totalCount, resultList);
}
In your repository class you create your query for the particular use case. Then you can use the method getPage to get the results in a Page.
public Page<Person> searchPerson(String name,
String phone,
PageRequest request){
Page<Person> results=null;
JPQLQuery<Person> query = new JPAQuery<>(entityManager);
QPerson person = QPerson.person;
query = query.from(person)
.where(person.name.eq(name)
.and(person.phone.eq(phone)));
return getPage(query, request);
}

Answer 2

The solution for the above was using BooleanBuilder implemented on the method above and changed the method name to return Person Object.
Please check BooleanBuilder
QPerson person= QPerson.person;
BooleanBuilder builder = this.getBuilder(name, phone,page, pageSize, sortFlag, sortItem);
PageRequest pg = getPRequest(page, pageSize);
Page<Person> pages personRepo.findAll(builder,pg);
return pages;
and then Implemented getBuilder Method for it which is the below one
public BooleanBuilder getBuilder(String name, String phone, Integer page, Integer pageSize, String sortFlag, String sortItem) {
QPerson person = QPerson.person;
BooleanBuilder builder = new BooleanBuilder();
builder.and(person.name.startsWith(name));
return builder;
}
and finally implemented the getPRequest Method as the following
public PageRequest getPRequest(Integer page, Integer pageSize) {
return new PageRequest(page, pageSize);
}
Oooooh Happy Days!