在 Spring 中使用带有 Pageable 的 findAll 的最佳方法是什么？

Question

I have employee class

@Entity
 class Employee {
     @Id
     Integer id;
     String name;
     Integer age;
}

and another class EmployeeInfo:

class EmployeeInfo {
         
     Integer id;
     String name;
 }

Now, I need to build a service to get a paginated list of EmployeeInfo by using findAll(Pageable pageable) from the repository

 @Repository
    public interface EmployeeRepository extends JpaRepository<Employee, Long> {

what is the best way to do that? I want to avoid getting the page from findAll and create a new object of EmployeeInfo then adding it to a list in a loop

Answer 1

You can utilize spring-data-jpa projections .
There are many ways to use them (open/closed projections, class or interface based, etc.), but since you already have a EmployeeInfo class, it can be achieved by defining a new method in your repository:

@Repository
public interface EmployeeRepository extends JpaRepository<Employee, Long> {
    Page<EmployeeInfo> getAllBy(Pageable pageable);
}

Note that your projection DTO class properties must exactly match properties in the aggregate root (entity class).
Also reference documentation suggest to define .equals() and .hashcode() methods.

Other methods can be found in the official documentation .