• I’m trying to create a map of students with the key being the period number and value being A list of all students with that period.
• The student object is marked as an entity.

    @OneToMany(cascade = CascadeType.ALL)
    @MapKey(name = "period")
    @JoinColumn(name = "teacher_id")
    private Map<Integer, List<Student>> students;

I also tried all this variation to students, but when i try to run the program. it shows the program having trouble creating the DB schema.

This one is orginzed by index being the period – 1.

    @ElementCollection
    @CollectionTable(name = "student_lists")
    @Column(name = "student_list")
    private List<List<Student>> students;

this is the main error im getting when i try to put a list in a list:
Error creating bean with name ‘entityManagerFactory’ defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]: Association ‘com.tracer.model.Teacher.studentsByPeriod’ targets the type ‘java.util.List’ which is not an ‘@Entity’ type

Currently I created a seperate entity CustomStudentList that stores the list of students: List>. But I would like to use a map instead.

I tried different variations. and got to the CustomStudentList which works, but is not ideal.