spring-data-jpa-pagination-sorting
Pagination and Sorting using Spring Data JPA
Further reading:
Spring Data JPA @Query
Learn how to use the @Query annotation in Spring Data JPA to define custom queries using JPQL and native SQL.
Derived Query Methods in Spring Data JPA Repositories
Explore the query derivation mechanism in Spring Data JPA.
2. Initial Setup
@Entity
public class Product {
@Id
private long id;
private String name;
private double price;
// constructors, getters and setters
}
as our domain class. Each of our Product instances has a unique identifier – id, its name and its price associated with it.
3. Creating a Repository
public interface ProductRepository extends PagingAndSortingRepository<Product, Integer> {
List<Product> findAllByPrice(double price, Pageable pageable);
}
By having it extend PagingAndSortingRepository, we get findAll(Pageable pageable) and findAll(Sort sort) methods for paging and sorting.
Or, we could have chosen to extend JpaRepository instead, as it extends PagingAndSortingRepository, too.
Once we extend PagingAndSortingRepository, we can add our own methods that take Pageable and Sort as parameters, as we did here with findAllByPrice.
Let’s take a look at how to paginate our Products using our new method.
4. Pagination
-
Create or obtain a PageRequest object, which is an implementation of the Pageable interface
-
Pass the PageRequest object as an argument to the repository method we intend to use
We can create a PageRequest object by passing in the requested page number and the page size.
Here, the page counts starts at zero:
Pageable firstPageWithTwoElements = PageRequest.of(0, 2);
Pageable secondPageWithFiveElements = PageRequest.of(1, 5);
In Spring MVC, we can also choose to obtain the Pageable instance in our controller using Spring Data Web Support.
Once we have our PageRequest object\, we can pass it in while invoking our repository’s method:
Page<Product> allProducts = productRepository.findAll(firstPageWithTwoElements);
List<Product> allTenDollarProducts =
productRepository.findAllByPrice(10, secondPageWithFiveElements);
The findAll(Pageable pageable) method by default returns a Page<T> object.
However, we can choose to return either a Page<T>, a Slice<T> or a List<T> from any of our custom methods returning a paginated data.
A Page<T> instance, in addition to having the list of Products, also knows about the total number of available pages. It triggers an additional count query to achieve it. To avoid such an overhead cost, we can instead return a Slice<T> or a List<T>.
A Slice only knows about whether the next slice is available or not.
5. Pagination and Sorting
Similarly, to just have our query results sorted, we can simply pass an instance of Sort to the method:
Page<Product> allProductsSortedByName = productRepository.findAll(Sort.by("name"));
However, what if we want to both sort and page our data?
We can do that by passing the sorting details into our PageRequest object itself:
Pageable sortedByName =
PageRequest.of(0, 3, Sort.by("name"));
Pageable sortedByPriceDesc =
PageRequest.of(0, 3, Sort.by("price").descending());
Pageable sortedByPriceDescNameAsc =
PageRequest.of(0, 5, Sort.by("price").descending().and(Sort.by("name")));
Based on our sorting requirements, we can specify the sort fields and the sort direction while creating our PageRequest instance.
As usual, we can then pass this Pageable type instance to the repository’s method.
6. Conclusion
As always, the complete code examples used in this tutorial are available over on Github.