@ManyToMany relationship attributes

[amitkhanna]

Hi

I have two entities Employee and Project in my application and there is many to many relationship between them. The application uses JPA and Hibernate. I have three tables:

employee: empId, name
project: projId, name
emp_proj: empId, projId

class Employee{
   ...
   @ManyToMany
   @JoinTable(.....)
   Collection<Project> projects;
   ....
}

class Project
   ...
   @ManyToMany(mappedby="projects")
   private Collection<Employee> employees;
   ....
}

Now I want to add information that who assigned a particular project to the employee, so the modified table looks like this:

emp_proj: empId, projId, assignee.

Since assignee is not the attribute of any of the two entities [i.e. employee or project] i can't access it.

One solution to this is that I make another entity for table emp_proj and break the relationship into two OneToMany relationships employee -> emp_proj and project -> emp_project.

Can anyone suggest a better solution by which i can access the attributes of the relationship?

Thanks
Amit Khanna

[gwa]

Hello,

You get the correct answer : transform your n-n relationship to two 1-n relationship.

There is no better choice.