Trying my hands at Spring Boot Pagination. But the resulting array is empty.

Controller:

package mypackage;
import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.domain.Page;
import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;
import org.springframework.data.domain.Sort;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class Controller {

    @Autowired
    CustomerRepository customerRepository;
    
    @GetMapping(value="/get/customers/{page}")
    public List<Customers> getCustomersPaginated(@PathVariable("page") int page)
    {
        Pageable pageableObject=PageRequest.of(page, 2, Sort.by("cnum").ascending());
        Page<Customers> pageObject = customerRepository.findAll(pageableObject);
        return pageObject.getContent();
    }
}

CustomerRepository:

package mypackage;
import org.springframework.data.jpa.repository.JpaRepository;

public interface CustomerRepository extends JpaRepository<Customers, Integer> {

}

Customers:

package mypackage;
import javax.persistence.Entity;
import javax.persistence.Id;

import lombok.Data;
import lombok.RequiredArgsConstructor;

@Entity//(name = "customers")
@Data
@RequiredArgsConstructor
public class Customers {
    
    @Id
    int cnum;
    int rating,snum;
    String cname, city;

}

Customers Table schema:

mysql> desc customers;
 -------- ------------- ------ ----- --------- ------- 
| Field  | Type        | Null | Key | Default | Extra |
 -------- ------------- ------ ----- --------- ------- 
| cnum   | int         | NO   | PRI | NULL    |       |
| cname  | varchar(20) | NO   |     | NULL    |       |
| city   | varchar(20) | NO   |     | NULL    |       |
| rating | int         | NO   |     | NULL    |       |
| snum   | int         | YES  | MUL | NULL    |       |
 -------- ------------- ------ ----- --------- ------- 

But the resulting array is empty, as shown in the following screenshot:

What do you think is the problem? It knows that I am requesting 2 results per page, but it is sending an array of null records. What am I missing here?

Edit 1: Eclipse logs. Why is it firing a query for count?

Edit 2: pom.xml:

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>SpringPagination</groupId>
  <artifactId>SpringPagination</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>war</packaging>
  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.0</version>
        <relativePath/> <!-- lookup parent from repository -->
  </parent>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-devtools</artifactId>
            <scope>runtime</scope>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
  <build>
    <plugins>
      <plugin>
        <artifactId>maven-compiler-plugin</artifactId>
        <version>3.8.1</version>
        <configuration>
          <release>17</release>
        </configuration>
      </plugin>
      <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
      <plugin>
        <artifactId>maven-war-plugin</artifactId>
        <version>3.2.3</version>
      </plugin>
    </plugins>
  </build>
</project>

CodePudding user response：

Pagination starts zero. Make sure you have enough rows. If there is any row, send page 0 and check if something is coming.

You can try:

PageRequest.of(0, 2);

or

For more detailed information on how to paginate, you can review.

CodePudding user response：

the query you are getting in logs , in the end there is limit ?,? which looks incorrect it should be limit ? offset ? when you are passing value of page other than 0

as for count query it gets executed when you don't have offset but since you are passing 1 for page than there should be offset and count query should not get executed , can you share you pom.xml need to check the version of dependencies you are using