grails - 在一张 table 上建立一对多的关系

Question

我有教师的父域和学生的子域(一对多)

学生拥有student_certificate实体，该实体是一个字节(确切地说是上传文件)

我在这里的关注点是我想分开student_certificate并创建另一个Student_attachment域，但是我想做的事情是将Student_attachment放在Student表上

可以这样做吗？因为存在数据，所以创建另一个表是一种冒险的方式

Answer 1

...but the twist i want to do is to lies the student_attachment on the table of Student

您可以使用 embedded属性，如下所示:

class Teacher {
    String name
    static hasMany = [students: Student]
}

class Student {
    String name
    StudentAttachment certificate
    static embedded = ['certificate']
}

class StudentAttachment {
    byte[] attachment
}


create table student (id bigint generated by default as identity, version bigint not null, name varchar(255) not null, certificate_attachment binary(255) not null, primary key (id));
create table teacher (id bigint generated by default as identity, version bigint not null, name varchar(255) not null, primary key (id));
create table teacher_student (teacher_students_id bigint not null, student_id bigint);