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POHibernate using of @ManyToMany and update both ways
 

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    <p>I have 2 classes, a Room class and a Student class. A Room can have many Students, while a Student also can have many Rooms. Therefore i used @ManyToMany relationship</p> <pre><code>public class Room { @ManyToMany private Collection&lt;Student&gt; studentList = new ArrayList&lt;Student&gt;(); } </code></pre> <hr> <pre><code>public class Student { @ManyToMany(mappedBy="studentList") private Collection&lt;Room&gt; roomList = new ArrayList&lt;Room&gt;(); } </code></pre> <p>Since i want to use 1 mapping table that is Room_Student, i was able to add a collection of Students to a Room. When I tried to add collection to a Student, hibernate did not save it. Here it is</p> <pre><code>Collection&lt;Student&gt; collectionOfStudents=new ArrayList&lt;Student&gt;(); Room room1=(Room) session.get(Room.class, 1); Student student1=(Student) session.get(Student.class, 1); Student student2=(Student) session.get(Student.class, 2); collectionOfStudents.add(student1); collectionOfStudents.add(student2); room1.getStudentList().addAll(collectionOfStudents) session.update(room1); </code></pre> <p>This worked and inserted to table Room_Student</p> <p>When i did</p> <pre><code>Collection&lt;Room&gt; collectionOfRooms=new ArrayList&lt;Room&gt;(); Student student1=(Student) session.get(Student.class, 1); Room room2=(Room) session.get(Room.class, 2); Room room3=(Room) session.get(Room.class, 3); collectionOfRooms.add(room2); collectionOfRooms.add(room3); student1.getRoomList().addAll(collectionOfRooms); session.update(student1); </code></pre> <p>it <strong>did not insert</strong> into table Room_Student for room2 and room3. Thanks for all the replies</p> <p>edited 1: i added</p> <pre><code>public class Student { @ManyToMany(mappedBy="studentList",cascade={CascadeType.ALL}) private Collection&lt;Room&gt; roomList = new ArrayList&lt;Room&gt;(); } </code></pre> <p>This</p> <pre><code>student1.getRoomList().addAll(collectionOfRooms); session.update(student1); </code></pre> <p>did not update/insert the rooms into table</p>
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