java - Spring Data - 按类型进行继承搜索

Question

假设我们有以下实体:

@Entity
@DiscriminatorColumn(name="Type")
@Inheritance(strategy=InheritanceType.Joined)
public abstract class Employee extends Persistable<Long> {

    private String firstName;
    private String lastName;

    //getters, setters
}

@Entity
@DiscriminatorValue("S")
public class SalariedEmployee extends Employee {
            //various fields
}

@Entity
@DiscriminatorValue("C")
public class ContractEmployee extends Employee {
            //various fields
}

@Entity
@DiscriminatorValue("H")
public class HourlyEmployee extends Employee {
            //various fields
}

还有一个存储库

public interface EmployeeRepository implements PagingAndSortingRepository<Employee, Long> {
}

我如何搜索执行查询，比如“将所有非小时员工的员工带给我”。显然，我需要对它们进行分页/排序，因此我可能无法执行 findAll(); 操作，如果我没有记错的话，只需从 Page 集合中删除条目即可。

Answer 1

查看 JPQL 类型运算符:

http://en.wikibooks.org/wiki/Java_Persistence/JPQL#JPQL_special_operators

JPA 2.0 规范(第 4.6.17.4 节)给出了以下使用示例:

SELECT e
FROM Employee e
WHERE TYPE(e) IN (Exempt, Contractor)

SELECT e
FROM Employee e
WHERE TYPE(e) IN (:empType1, :empType2)

SELECT e
FROM Employee e
WHERE TYPE(e) IN :empTypes

SELECT TYPE(e)
FROM Employee e
WHERE TYPE(e) <> Exempt