我在JPA Repository类中有一个自定义查询:
package it.univaq.we.internshipTutor.repository;
import ...
public interface ProfessorRepository extends JpaRepository<Professor, Long> {
List<Professor> findAll();
...
@Query(value = "SELECT professor.id, professor.department_id, " +
"professor.first_name, professor.last_name, " +
"professor.email, COUNT(professor_id) as count " +
"FROM professor LEFT JOIN student_internship ON professor.id = professor_id " +
"GROUP BY professor_id ORDER BY count DESC LIMIT ?1", nativeQuery = true)
List<ProfessorInternshipCount> mostRequestedProfessors(int limit);
}
该查询返回前10名最受欢迎的实习导师/教授;结果由教授信息和一个整数值(计数)组成。
教授模型类:
package it.univaq.we.internshipTutor.model;
import ...
@Entity
@Table(name = "professor")
public class Professor {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", nullable = false)
private Long id;
@Transient
private UUID uuid;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "department_id", nullable = false)
@NotNull(message = "this field is mandatory")
private Department department;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "professor")
private List<StudentInternship> studentInternships;
@Column(name = "first_name", nullable = false, length = 255)
@NotEmpty
private String firstName;
@Column(name = "last_name", nullable = false, length = 255)
@NotEmpty
private String lastName;
@Column(name = "email", nullable = false, length = 255)
@Email
@NotEmpty
private String email;
...getters and setters...
}
ProfesssorInternshipCount模型(用于封装查询结果):
package it.univaq.we.internshipTutor.model;
public class ProfessorInternshipCount {
private Professor professor;
private Integer count;
public ProfessorInternshipCount(Professor professor, int count) {
this.professor = professor;
this.count = count;
}
...getters and setters...
}
现在,我在将查询结果与已创建的模型绑定时遇到了困难。 更准确地说,我遇到了以下异常:
org.springframework.core.convert.ConverterNotFoundException:
No converter found capable of converting from type
[org.springframework.data.jpa.repository.query.AbstractJpaQuery$TupleConverter$TupleBackedMap]
to type
[it.univaq.we.internshipTutor.model.ProfessorInternshipCount]
...
我做错了什么吗?有没有更好的方法来完成我正在尝试做的事情?