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我正在尝试使用 CriteriaUpdate 更新多对多关系。

以下是实体；

@Entity
@Table(name = "COURSE")
public class Course {
    @Id
    @GeneratedValue
    private String id;
    
    private String name;
    
    // Getters and setter...
}

@Entity
@Table(name = "STUDENT")
public class Student {
    @Id
    @GeneratedValue
    private String id;
    
    private String name;
    
    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable(name = "STUDENT_COURSE", joinColumns = {@JoinColumn(name = "STUDENT_ID")}, inverseJoinColumns = {@JoinColumn(name = "COURSE_ID")})
    private Set<Course> courses = new HashSet<>();

    // Getters and setter...
}

下面是DAO中的代码

void updateCourses(String studentId, Set<Course> courses){
    CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
    CriteriaUpdate<Student> criteriaUpdate = criteriaBuilder.createCriteriaUpdate(Student.class);
    Root<Student> studentRoot = criteriaUpdate.from(Student.class);
    criteriaUpdate.where(criteriaBuilder.equal(studentRoot.get("id"), studentId));
    criteriaUpdate.set("courses", courses);
    entityManager.createQuery(criteriaUpdate).executeUpdate();
}

上面的代码抛出以下异常

java.lang.IllegalArgumentException: Attribute path for assignment must represent a singular attribute [null.courses]

如何使用 CriteriaUpdate 进行更新？

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0 回答 0