使用子句引用实体的字段值的Hibernate ManyToMany。

Question

我有实体Group和Course。也有一个ManyToMany关系表。我想只获取该组的活动课程。

我如何在@WhereJoinTable()中设置一个条件，只过滤匹配的课程。Group.isActive = true, and semester_number = Group.currentSemester ?

还是有其他的方法来实现？

@Entity
@Table(name = "courses")
public class Course {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String name;
    private String description;

    @ManyToMany(mappedBy = "activeCourses")
    private Set<Group> groups = new HashSet<>();
}



@Entity
        @Table(name = "groups")
        public class Group {

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        private long id;

        private String name;

        @Column(name = "current_semester")
        private int currentSemester;

        @Column(name = "total_semesters")
        private int totalSemesters;

        @Column(name = "is_active")
        private Boolean isActive;

        @Column(name = "department_id")
        private long departmentId;

        @ManyToMany(fetch = FetchType.EAGER)
        @JoinTable(name = "assigned_courses", joinColumns = {@JoinColumn(name = "group_id")},
            inverseJoinColumns = {@JoinColumn(name = "course_id")})
        @WhereJoinTable(clause = "semester_number ="))
        private Set<Course> activeCourses = new HashSet<>();
}

Answer 1

我通过在DAO层单独写一个查询来解决这个问题。看起来简单灵活多了。