BAEL-8999 (#18651)

Co-authored-by: Wynn Teo <[email protected]>

Author: wynnteo

spring-boot-modules/spring-boot-graphql-2/src/main/java/com/baeldung/pagination/GraphqlPagination.java

@@ -0,0 +1,12 @@
+package com.baeldung.pagination;
+
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class GraphqlPagination {
+    public static void main(String[] args) {
+        SpringApplication.run(GraphqlPagination.class, args);
+    }
+}

spring-boot-modules/spring-boot-graphql-2/src/main/java/com/baeldung/pagination/dto/BookConnection.java

@@ -0,0 +1,16 @@
+package com.baeldung.pagination.dto;
+
+import lombok.Getter;
+
+import java.util.List;
+
+@Getter
+public class BookConnection {
+    private final List<BookEdge> edges;
+    private final PageInfo pageInfo;
+
+    public BookConnection(List<BookEdge> edges, PageInfo pageInfo) {
+        this.edges = edges;
+        this.pageInfo = pageInfo;
+    }
+}

spring-boot-modules/spring-boot-graphql-2/src/main/java/com/baeldung/pagination/dto/BookEdge.java

@@ -0,0 +1,16 @@
+package com.baeldung.pagination.dto;
+
+import com.baeldung.pagination.entity.Book;
+
+import lombok.Getter;
+
+@Getter
+public class BookEdge {
+    private final Book node;
+    private final String cursor;
+
+    public BookEdge(Book node, String cursor) {
+        this.node = node;
+        this.cursor = cursor;
+    }
+}

spring-boot-modules/spring-boot-graphql-2/src/main/java/com/baeldung/pagination/dto/BookPage.java

@@ -0,0 +1,25 @@
+package com.baeldung.pagination.dto;
+
+import lombok.Getter;
+import org.springframework.data.domain.Page;
+
+import java.util.List;
+
+import com.baeldung.pagination.entity.Book;
+
+@Getter
+public class BookPage {
+    private final List<Book> content;
+    private final int totalPages;
+    private final long totalElements;
+    private final int number;
+    private final int size;
+
+    public BookPage(Page<Book> page) {
+        this.content = page.getContent();
+        this.totalPages = page.getTotalPages();
+        this.totalElements = page.getTotalElements();
+        this.number = page.getNumber();
+        this.size = page.getSize();
+    }
+}

spring-boot-modules/spring-boot-graphql-2/src/main/java/com/baeldung/pagination/dto/PageInfo.java

@@ -0,0 +1,14 @@
+package com.baeldung.pagination.dto;
+
+import lombok.Getter;
+
+@Getter
+public class PageInfo {
+    private final boolean hasNextPage;
+    private final String endCursor;
+
+    public PageInfo(boolean hasNextPage, String endCursor) {
+        this.hasNextPage = hasNextPage;
+        this.endCursor = endCursor;
+    }
+}

spring-boot-modules/spring-boot-graphql-2/src/main/java/com/baeldung/pagination/entity/Book.java

@@ -0,0 +1,42 @@
+package com.baeldung.pagination.entity;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.GenerationType;
+import jakarta.persistence.Id;
+import lombok.Getter;
+import lombok.Setter;
+
+@Entity
+public class Book {
+    @Id
+    @GeneratedValue(strategy = GenerationType.IDENTITY)
+    private Long id;
+
+    private String title;
+    private String author;
+
+    public Long getId() {
+        return this.id;
+    }
+
+    public String getTitle() {
+        return this.title;
+    }
+
+    public String getAuthor() {
+        return this.author;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+}

spring-boot-modules/spring-boot-graphql-2/src/main/java/com/baeldung/pagination/repository/BookRepository.java

@@ -0,0 +1,16 @@
+package com.baeldung.pagination.repository;
+
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.PagingAndSortingRepository;
+import org.springframework.stereotype.Repository;
+
+import java.util.List;
+
+import com.baeldung.pagination.entity.Book;
+
+@Repository
+public interface BookRepository extends PagingAndSortingRepository<Book, Long>, CrudRepository<Book, Long> {
+    List<Book> findByIdGreaterThanOrderByIdAsc(Long cursor, org.springframework.data.domain.Pageable pageable);
+    List<Book> findAllByOrderByIdAsc(org.springframework.data.domain.Pageable pageable);
+    boolean existsByIdGreaterThan(Long id);
+}

spring-boot-modules/spring-boot-graphql-2/src/main/java/com/baeldung/pagination/resolver/BookQueryResolver.java

@@ -0,0 +1,56 @@
+package com.baeldung.pagination.resolver;
+
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import org.springframework.graphql.data.method.annotation.Argument;
+import org.springframework.graphql.data.method.annotation.QueryMapping;
+import org.springframework.stereotype.Controller;
+
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+
+import com.baeldung.pagination.dto.BookConnection;
+import com.baeldung.pagination.dto.BookEdge;
+import com.baeldung.pagination.dto.BookPage;
+import com.baeldung.pagination.dto.PageInfo;
+import com.baeldung.pagination.entity.Book;
+import com.baeldung.pagination.repository.BookRepository;
+
+@Controller
+public class BookQueryResolver {
+    private final BookRepository bookRepository;
+
+    public BookQueryResolver(BookRepository bookRepository) {
+        this.bookRepository = bookRepository;
+    }
+
+    @QueryMapping
+    public BookPage books(@Argument int page, @Argument int size) {
+        Pageable pageable = PageRequest.of(page, size);
+        Page<Book> bookPage = bookRepository.findAll(pageable);
+        return new BookPage(bookPage);
+    }
+
+    @QueryMapping
+    public BookConnection booksByCursor(@Argument Optional<Long> cursor, @Argument int limit) {
+        List<Book> books;
+
+        if (cursor.isPresent()) {
+            books = bookRepository.findByIdGreaterThanOrderByIdAsc(cursor.get(), PageRequest.of(0, limit));
+        } else {
+            books = bookRepository.findAllByOrderByIdAsc(PageRequest.of(0, limit));
+        }
+
+        List<BookEdge> edges = books.stream()
+            .map(book -> new BookEdge(book, book.getId().toString()))
+            .collect(Collectors.toList());
+        String endCursor = books.isEmpty() ? null : books.get(books.size() - 1).getId().toString();
+        boolean hasNextPage = !books.isEmpty() && bookRepository.existsByIdGreaterThan(books.get(books.size() - 1).getId());
+
+        PageInfo pageInfo = new PageInfo(hasNextPage, endCursor);
+
+        return new BookConnection(edges, pageInfo);
+    }
+}

spring-boot-modules/spring-boot-graphql-2/src/main/resources/application-pagination.yml

@@ -0,0 +1,23 @@
+spring:
+  datasource:
+    url: jdbc:h2:mem:testdb  # H2 in-memory DB
+    username: sa
+    password: password
+    driver-class-name: org.h2.Driver
+  h2:
+    console:
+      enabled: true
+      path: /h2-console
+  jpa:
+    hibernate:
+      ddl-auto: update
+    show-sql: false
+    properties:
+      hibernate.format_sql: true
+
+  graphql:
+    servlet:
+      enabled: true
+      path: /graphql
+    schema:
+      locations: classpath:pagination/

spring-boot-modules/spring-boot-graphql-2/src/main/resources/pagination/schema.graphqls

@@ -0,0 +1,33 @@
+type Book {
+    id: ID!
+    title: String
+    author: String
+}
+
+type BookPage {
+    content: [Book]
+    totalPages: Int
+    totalElements: Int
+    number: Int
+    size: Int
+}
+
+type BookEdge {
+    node: Book
+    cursor: String
+}
+
+type PageInfo {
+    hasNextPage: Boolean
+    endCursor: String
+}
+
+type BookConnection {
+    edges: [BookEdge]
+    pageInfo: PageInfo
+}
+
+type Query {
+    books(page: Int, size: Int): BookPage
+    booksByCursor(cursor: ID, limit: Int!): BookConnection
+}