SpringData Pageable Arayüzü - Metoda Parametre Olarak Verilir

Giriş
Şu satırı dahil ederiz.

import org.springframework.data.domain.Pageable;

Pageable nesnesi repository nesneler ile birlikte kullanılır. Açıklaması şöyle. Pageable Arayüzü metoda parametre olarak verilir. Metod Page nesnesi döner.

Problem
- Typically OLTP users do not consume large amount of data so it is wastage of processing resources.
- Severe system performance issue can arise depending on the volume of data

Solution :
- Paginate results
- Narrow down search criteria

Örnek

Metod şöyledir

@GetMapping(value = "/fetchCustomerByLastNamePagination")
public ResponseEntity<Page<Customer>> fetchCustomerByLastNamePagination(@RequestParam String lastName, int pageId, int pageSize) throws RuntimeException {
  return new ResponseEntity<>(customerService.findCustomerByLastNamePagination(lastName, pageId, pageSize), HttpStatus.OK);
}
    
-- Request
http://localhost:8081/springreadyapp/fetchCustomerByLastNamePagination?lastName=Karim&pageId=0&pageSize=2

    
-- Generated query
Hibernate: 
    select
        customer0_.id as id1_0_,
        customer0_.first_name as first_na2_0_,
        customer0_.gender as gender3_0_,
        customer0_.last_name as last_nam4_0_,
        customer0_.mobile_number as mobile_n5_0_,
        customer0_.present_address as present_6_0_,
        customer0_.permanent_address as permanen7_0_ 
    from
        customer customer0_ 
    where
        customer0_.last_name=? limit ?
Hibernate: 
    select
        count(customer0_.id) as col_0_0_ 
    from
        customer customer0_ 
    where
        customer0_.last_name=?

Çıktı şöyledir

-- Response
{
  "content": [
    {
      "id": 1,
      "firstName": "Sajedul",
      "lastName": "Karim",
      "mobileNumber": "01737186095",
      "presentAddress": "Dhaka",
      "permanentAddress": "Nilphamari",
      "gender": "Male"
    },
    {
      "id": 2,
      "firstName": "Sajedul",
      "lastName": "Karim",
      "mobileNumber": "01737186095",
      "presentAddress": "Dhaka",
      "permanentAddress": "Nilphamari",
      "gender": "Male"
    }
  ],
  "pageable": {
    "sort": {
      "sorted": false,
      "unsorted": true,
      "empty": true
    },
    "offset": 0,
    "pageSize": 2,
    "pageNumber": 0,
    "paged": true,
    "unpaged": false
  },
  "totalPages": 21,
  "totalElements": 41,
  "last": false,
  "numberOfElements": 2,
  "first": true,
  "size": 2,
  "number": 0,
  "sort": {
    "sorted": false,
    "unsorted": true,
    "empty": true
  },
  "empty": false
}

Örnek

Elimizde şöyle bir kod olsun

@Data
@Document(collection = "tweets")
public class Tweet {
    private ObjectId id;
    private String author;
    private String content;
    private Long createdAt;
}
public interface TweetRepository extends MongoRepository<Tweet, ObjectId> {
}
@GetMapping(value = "/paged")
public Page<Tweet> getPaged(Pageable pageable) {
   return tweetRepository.findAll(pageable);
}

Şöyle yaparız. Burada Spring akıllı ve URL parametrelerinden bir tane Pageable nesnesi yarattı.

http://myapi.com/tweets?size=10&page=1

Örnek

Şöyle yaparız.. Burada metodumuza iki tane parametre geçiliyor. Biz de PageRequest nesnesini kullanarak bir Pageable yaratıypruz.

public Optional<Page<User>> getAllByPage(Integer pageSize, Integer page) {
  Pageable pageable = PageRequest.of(page, pageSize);
  return userRepository.findAll(pageable);
}

Örnek
Şöyle yaparız.

Cacheable(key = "#pageable.pageNumber")
public Person getPersons(Pageable pageable)