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From "Pinaki Poddar" <>
Subject RE: Can't get column names in a join table correct
Date Mon, 25 Jun 2007 03:38:03 GMT

One way to match the Java classes and the tomcat's user-role schema is
shown below:
public class User {
	private String userId;
	private String password;
	private List<Role> roles;

public class Role {
	private User userId;
	private String roleName;
	public static class RoleId {
		public String userId;
		public String roleName;
		// *** Must write equals() and hasCode() method properly


On MySQL the above class definitions + O-R mapping spec will be mapped

CREATE TABLE Users (userId VARCHAR(255) NOT NULL, password VARCHAR(255),
PRIMARY KEY (userId));
NULL, PRIMARY KEY (role, userId));

This is pretty much the same as tomcat's schema.

Please note how OpenJPA supports entity relation as primary key to
achieve this (Role.userId is part of the compound key).

Also Role.RoleId class must write equals() and hashCode() methods in a
compliant way. What is 'compliant' is described

Pinaki Poddar

-----Original Message-----
From: Jere McDevitt [] 
Sent: Sunday, June 24, 2007 9:36 PM
Subject: Can't get column names in a join table correct

As my first try at using openjpa-1.0.0-SNAPSHOT (with Postgres) I'm
trying to create classes that will map into tables that can be used by
tomcat realm security.  Tomcat requires the following exist for database
security to work:

A user table with fields to hold a userid and a password.
A role table with fields to hold a userid and a role.

When doing it manually, the schema looked like:

create table users (
       userid  varchar(32) primary key not null,
       password varchar(64) not null

create table roles (
       userid  varchar(32) not null,
       role   varchar(32) not null,
       primary key (userid, role)

Then, in the context.xml file for a web application, you have to provide

<Realm className="org.apache.catalina.realm.DataSourceRealm"

As you can see, the userid field must have the same name in both tables
for tomcat to use this structure for user authentication.

I have tried multiple ways to get a proper table structure built.  I
created a class that looks like

public class User implements Serializable {
       String	  userid;
       String	  password;

       ArrayList<Role>	roles


and a class that looks like

public class Role implements Serializable {

       String		roleName;

Then I create a single user with one role

     User u = new User("user","password");
     Role r = new Role("admin");
     u.addRole(r);	//puts it in the roles arraylist

and I do all the normal steps to apply these, first persisting the role
object, then persisting the user object.

I end up with 2 tables, users and roles. The users table has the User
object in it but it stores the array list as a byte array. Not what I

So I change the User class to look like:

public class User implements Serializable {
       String	  userid;
       String	  password;

       ArrayList<Role>	roles


So now I get 3 tables, the User object in users, the Role object in
roles and the users_roles table now has a single entry with the userid
field as requested, but it now has the byte array of data from the roles

I've tried to declare the attribute @ManyToMany and it puts the data
into a table called user_role but the fields are named user_userid and
roles_rolename because it will not allow the @Column setting with the

Any ideas how to structure the classes and/or annotations to get the
table constructs needed?

Thanks in advance


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