Java – spring data JPA – custom sorting in jparepository

I used spring data JPA and spring data rest and created a jparepository for my thing entity

@Repository
public interface ThingRepository extends JpaRepository<Thing,Long> {

    @RestResource(path = "findByName",rel = "findByName")
    Page findByName(@Param("name") String name,Pageable page);

}

I want to apply for ranking I want to sort the thing list according to the custom rating algorithm

List<Thing> sortByrating(List<Thing> things){

    // custom logic

    return things;
};

I want to use custom functions as much as possible to sort the results What is the best way to do this in spring JPA? How do I get my repository to use my functions to sort result sets?

Solution

Spring data provides basic sorting, as shown here You can also annotate the query with @ query and use order by, but I believe what you need is more complex sorting logic

If you are using java 8, you can use its function to sort the list. This article shows a good example. It needs more work, but it looks like what you are looking for Note that to convert from a stream to a list, you must include collect(Collectors.toList()); At the end of the stream

Example (from article):

employees.stream().sorted((Employee e1,Employee e2) -> e1.getHireDate()
                        .compareTo(e2.getHireDate())).collect(Collectors.toList());

Editor: I didn't notice you were using paging I have a similar problem. I have to do something about the page content before returning the page object, so I finally created the extension of pageimpl < T > Class:

public class PageImplBean<T> extends PageImpl<T> {

    private static final long serialVersionUID = 1L;
    private int number;
    private int size;
    private int totalPages;
    private int numberOfElements;
    private long totalElements;
    private boolean prevIoUsPage;
    private boolean first;
    private boolean nextPage;
    private boolean last;
    private List<T> content;
    @JsonIgnore
    private Sort sort;

    public PageImplBean() {
        super(new ArrayList<T>());
    }

    public PageImplBean(Page pagina){
        super(new ArrayList<T>());
        this.number = pagina.getNumber();
        this.size = pagina.getSize();
        this.totalPages = pagina.getTotalPages();
        this.numberOfElements = pagina.getNumberOfElements();
        this.totalElements = pagina.getTotalElements();
        this.prevIoUsPage = pagina.hasPrevIoUs();
        this.first = pagina.isFirst();
        this.nextPage = pagina.hasNext();
        this.last = pagina.isLast();
    }

    public int getNumber() {
        return number;
    }

    public void setNumber(int number) {
        this.number = number;
    }

    public int getSize() {
        return size;
    }

    public void setSize(int size) {
        this.size = size;
    }

    public int getTotalPages() {
        return totalPages;
    }

    public void setTotalPages(int totalPages) {
        this.totalPages = totalPages;
    }

    public int getNumberOfElements() {
        return numberOfElements;
    }

    public void setNumberOfElements(int numberOfElements) {
        this.numberOfElements = numberOfElements;
    }

    public long getTotalElements() {
        return totalElements;
    }

    public void setTotalElements(long totalElements) {
        this.totalElements = totalElements;
    }

    public boolean isPrevIoUsPage() {
        return prevIoUsPage;
    }

    public void setPrevIoUsPage(boolean prevIoUsPage) {
        this.prevIoUsPage = prevIoUsPage;
    }

    public boolean isFirst() {
        return first;
    }

    public void setFirst(boolean first) {
        this.first = first;
    }

    public boolean isNextPage() {
        return nextPage;
    }

    public void setNextPage(boolean nextPage) {
        this.nextPage = nextPage;
    }

    public boolean isLast() {
        return last;
    }

    public void setLast(boolean last) {
        this.last = last;
    }

    public List<T> getContent() {
        return content;
    }

    public void setContent(List<T> content) {
        this.content = content;
    }

    public Sort getSort() {
        return sort;
    }

    public void setSort(Sort sort) {
        this.sort = sort;
    }

    public PageImpl<T> pageImpl() {
        return new PageImpl<T>(getContent(),new PageRequest(getNumber(),getSize(),getSort()),getTotalElements());
    }
}

In your case, the important thing is the setcontent method, which does not exist in the base class You can use it with your sorting method:

PageImplBean<Thing> page = //call your rest repository
List<Thing> pageContent = page.getContent();
page.setContent(sortByrating(pageContent));