6. Paging Query

Two types of Page objects

Jimmer supports built-in Page objects

• org.babyfish.jimmer.Page<T>

• org.springframework.data.domain.Page<T>

note

In fact, Jimmer allows users to customize any Page object. However, this article does not discuss this issue, partly because this article is only a showcase page and does not want to go into depth, and on the other hand, these two built-in Page objects are usually sufficient.

As far as these two built-in Page objects are concerned, the differences are as follows:

• org.springframework.data.domain.Page<T>: Designed for server-side pages, in order for the page to remain in its previous state after refresh, a lot of information (such as cumbersome sorting information) needs to be returned to the client as is, so it is very complex.

• org.babyfish.jimmer.Page<T>: For the design of rich client pages, this kind of client page itself is a stateful application, and the server side provide pure data services, and only return the most necessary information, so it is very simple.

Using the page of Jimmer

Java

int pageIndex = ...Omitted...; // 从0开始
int pageSize = ...Omitted...;

BookTable table = BookTable.$;
org.babyfish.jimmer.Page<Book> page = sqlClient
    .createQuery(table)
    .orderBy(table.name().asc())
    .orderBy(table.edition().desc())
    .select(table)
    .fetchPage(pageIndex, pageSize);

Kotlin

val pageIndex: Int = ...Omitted...; // Starts from 0
val pageSize: Int = ...Omitted...;

val page: org.babyfish.jimmer.Page<Book> = sqlClient
    .createQuery(Book::class) {
        orderBy(table.name.asc())
        orderBy(table.edition().desc())
        select(table)
    }
    .fetchPage(pageIndex, pageSize)

If pageIndex is 1 * (page 2) * and pageSize is 5, the result is

Page{
    rows=[
        {
            "id":10,
            "name":"GraphQL in Action",
            "edition":1,
            "price":82.00,
            "store":{"id":2}
        }, 
        {
            "id":3,
            "name":"Learning GraphQL",
            "edition":3,
            "price":51.00,
            "store":{"id":1}
        }, 
        {
            "id":2,
            "name":"Learning GraphQL",
            "edition":2,
            "price":55.00,
            "store":{"id":1}
        }, 
        {
            "id":1,
            "name":"Learning GraphQL",
            "edition":1,
            "price":50.00,
            "store":{"id":1}
        }, 
        {
            "id":9,
            "name":"Programming TypeScript",
            "edition":3,
            "price":48.00,
            "store":{"id":1}
        }
    ], 
    totalRowCount=12, 
    totalPageCount=3
}

Using the page of Spring Data

After importing the dependency 'org.babyfish.jimmer:jimmer-spring-boot-starter:$version'

• Usage supported by both Java and Kotlin: Use SpringPageFactory.getInstance() as the third argument to fetchPage

• Kotlin-specific usage: Directly call the extension function fetchSpringPage.

Java

int pageIndex = ...Omitted...; // 从0开始
int pageSize = ...Omitted...;

BookTable table = BookTable.$;
org.springframework.data.domain.Page<Book> page = sqlClient
    .createQuery(table)
    .orderBy(table.name().asc())
    .orderBy(table.edition().desc())
    .select(table)
    .fetchPage(
        pageIndex, 
        pageSize,
        SpringPageFactory.getInstance()
    );

Kotlin

val pageIndex: Int = ...Omitted...; // Starts from 0
val pageSize: Int = ...Omitted...;

val page: org.springframework.data.domain.Page<Book> = sqlClient
    .createQuery(Book::class) {
        orderBy(table.name.asc())
        orderBy(table.edition().desc())
        select(table)
    }
    .fetchSpringPage(
        pageIndex, 
        pageSize
    )

If pageIndex is 1 * (page 2) * and pageSize is 5, the result is

{
    "content":[
        {
            "id":10,
            "name":"GraphQL in Action",
            "edition":1,
            "price":82,
            "store":{"id":2}
        },
        {
            "id":3,
            "name":"Learning GraphQL",
            "edition":3,
            "price":51,
            "store":{"id":1}
        },
        {
            "id":2,
            "name":"Learning GraphQL",
            "edition":2,
            "price":55,
            "store":{"id":1}
        },
        {
            "id":1,
            "name":"Learning GraphQL",
            "edition":1,
            "price":50,
            "store":{"id":1}
        },
        {
            "id":9,
            "name":"Programming TypeScript",
            "edition":3,
            "price":48,
            "store":{"id":1}
        }
    ],
    "pageable":{
        "sort":{
            "unsorted":false,
            "sorted":true,
            "empty":false
        },
        "pageNumber":1,
        "pageSize":5,
        "offset":5,
        "paged":true,
        "unpaged":false
    },
    "totalPages":3,
    "totalElements":12,
    "last":false,
    "numberOfElements":5,
    "first":false,
    "size":5,
    "number":1,
    "sort":{
        "unsorted":false,
        "sorted":true,
        "empty":false
    },
    "empty":false
}