Limiting the visibility of results from the database on one page- spring boot

Question

I create web application in spring boot using the postgress database.

I want to limit the number of records per page(now it's 30,000 records - it's loading a long time), so what should i do to limit it? I use thymeleaf.

Model:

@Entity(name="articles")
@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})
public class Articles {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long article_id;
private String title;
private String issn;
private String eissn;
private String title2;
private String issn2;
private String eissn2;
private Integer points;

@ManyToMany
@JoinTable(
        name = "articles_categories",
        joinColumns = @JoinColumn(name = "article_id"),
        inverseJoinColumns = @JoinColumn(name = "category_id"))
private List<Category> categories;
....

getters and setters

Repository:

public interface ArticlesRepository extends JpaRepository<Articles,Long> {
}

Controller:

@Controller
@RequestMapping("/articles")
public class ArticlesController {


private ArticleService articleService;

@Autowired
public void setArticleService(ArticleService articleService) {
    this.articleService = articleService;
}

@GetMapping 
public String getAll(Model model)
{
    model.addAttribute("articles", articleService.list());
    return "articles"; 
}

Service:

@Service
public class ArticleService {


@Autowired
private ArticlesRepository articlesRepository;

public ArticleService() {
}

public List<Articles> list(){
    return articlesRepository.findAll();
}}

Shekhar Rai · Accepted Answer · 2020-01-22T15:31:55.903

1

Use Pageable to limit the size of your articles.

public List<Articles> list(int page, int limit){
    Page<Articles> pageableArticales = articlesRepository.findAll(PageRequest.of(page, limit);
    return pageableArticales.getContent();
}

Note that repository.findAll(pageable) wraps the list of data on Page, which provides getNumber(), getSize(), getNumberOfElements(), getTotalPages(), getTotalElements, etc.

And consider exploring PageRequest and PagedResources as well.

edited Jan 22 '20 at 15:31

answered Jan 22 '20 at 14:45

Shekhar Rai

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Check this question: https://stackoverflow.com/q/9314078/11733759 – lczapski Jan 22 '20 at 15:07
Should I change something in my thymeleaf template? I ask because when I set for example page=100 and limit=40 in my Controllers method,I received only 40 records without being able to go to the next page or sth like that to view more records. What should I do to be able to navigate pages with other records? – spaceoddity11 Jan 22 '20 at 15:18
You may consider seeing [hateos](https://www.baeldung.com/rest-api-pagination-in-spring) to navigate pages. Or you can use `getTotalElements()` / `getTotalPages()` as well. And `page` and `limit` you can pass through your *model*(`getAll(Model model)`) – Shekhar Rai Jan 22 '20 at 15:24
See [PagedResources](https://docs.spring.io/spring-hateoas/docs/0.25.3.BUILD-SNAPSHOT/api/org/springframework/hateoas/PagedResources.html) as well to use hateoas links.. – Shekhar Rai Jan 22 '20 at 15:31
What do you mean by 'And page and limit you can pass through your *model*(getAll(Model model))'? – spaceoddity11 Jan 22 '20 at 16:12
@spaceoddity11 my bad you should pass using @RequestParam like `@GetMapping public String getAll(@RequestParam int page, @RequestParam int size, Model model)` and your URL should be like `/articles?limit=40&page=100` – Shekhar Rai Jan 22 '20 at 16:20
Ok, but how can I navigate between the pages avoid writing in my browser exact number of page and limit on the page? – spaceoddity11 Jan 22 '20 at 16:29
`PagedResources` is what you should do - implementing `hateoas` you get links to navigate next/previous pages. You should put page(1) and size(40) by default and request to your controller - which gives you links as well. try exploring hateos. – Shekhar Rai Jan 22 '20 at 16:37
For example, if you click [here- stackoverflow questions](https://stackoverflow.com/questions), and if you scroll down to the end you can see a list of page buttons like 1,2,3......[lastPage] and 15, 30, 50 per page (limit). – Shekhar Rai Jan 22 '20 at 16:38

Limiting the visibility of results from the database on one page- spring boot

1 Answers1