[Dr.Drane]

Hello,

When I try to reverse engineer a simple database with a many-to-many relationship, like this:

I also get a class for the User_has_language table. Is this normal?

Because having a User with a collection of Language and vice versa seems to logical OO variant of this database. Why would I need a User_has_language object?

I hope my question is a bit clearly formulated.

Thanks a lot in advance and have a nice day!

Jochen

[support-shalini]

Jochen,
You can check the “Enable many-to-many detection” option to avoid user_has_language objects.
You will have to remove the previously generated code and RE again.
Let me know if that helps.

[Dr.Drane]

Hi Shaline,

That din’t help unfortunately. I still get the XXXhasYYY objects.
If you want I can post or mail the .sql file so you can see for yourself that it doesn’t seem to work.

Thanks a lot in advance!

Kind regards,

Jochen

[Dr.Drane]

To give you some more info:

I create a new web project. Add Spring 2.5 functionality. Add JPA (via Hibernate) functionality.
Then I generate entities & DAO’s from the database using Spring DAO’s and I make sure that the “Enable many-to-many detection” is marked.

This is the database:

— phpMyAdmin SQL Dump
— version 3.1.3.1
— http://www.phpmyadmin.net
—
— Host: localhost
— Generation Time: Sep 22, 2009 at 03:42 PM
— Server version: 5.1.33
— PHP Version: 5.2.9

SET SQL_MODE=”NO_AUTO_VALUE_ON_ZERO”;

—
— Database: `testdb`
—

— ——————————————————–

—
— Table structure for table `language`
—

CREATE TABLE IF NOT EXISTS `language` (
`idlanguage` int(11) NOT NULL,
`name` varchar(45) DEFAULT NULL,
PRIMARY KEY (`idlanguage`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

—
— Dumping data for table `language`
—

— ——————————————————–

—
— Table structure for table `user`
—

CREATE TABLE IF NOT EXISTS `user` (
`idUser` int(11) NOT NULL,
`name` varchar(45) DEFAULT NULL,
`password` varchar(45) DEFAULT NULL,
PRIMARY KEY (`idUser`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

—
— Dumping data for table `user`
—

— ——————————————————–

—
— Table structure for table `user_has_language`
—

CREATE TABLE IF NOT EXISTS `user_has_language` (
`User_idUser` int(11) NOT NULL,
`language_idlanguage` int(11) NOT NULL,
PRIMARY KEY (`User_idUser`,`language_idlanguage`),
KEY `fk_User_has_language_User` (`User_idUser`),
KEY `fk_User_has_language_language` (`language_idlanguage`)
) Engine=InnoDB DEFAULT CHARSET=latin1;

—
— Dumping data for table `user_has_language`
—

[support-shalini]

Jochen,
I could not replicate this at my end. I created a new web project, added spring 2.5 capabilities, added JPA capabiliites (selected Hibernate when adding JPA). When I selected “Generate Entities and DAO’s” from the context menu of the project and checked the option “Enable many-to-many detection”, XXXhasYYY objects are not generated.
I have attached a screen shot for your reference.

Attachments:

You must be logged in to view attached files.

[Dr.Drane]

That is very odd…I get a different result:

What version of mysql DB / mysql driver jar / MyEclipse are you using?
You leave all the settings (including the annotions settings) just to default?

Thanks again for all the help!

Kind regards,

Jochen

[support-shalini]

Jochen,
This is really strange. I have the same settings here. I tested with MySql 5, ME7.5 and mysql-connector-java-3.1.14-bin.jar.
One quick question. Did you delete all your previously generated classes before generating entities and DAO’s again?
From the above screen shot, I notice that you can safely remove the package be.tradelec.model.
Can you remove the package and do the generation again?
Let me know if you still have the issue.

[Dr.Drane]

@support-shalini wrote:

Jochen,
This is really strange. I have the same settings here. I tested with MySql 5, ME7.5 and mysql-connector-java-3.1.14-bin.jar.
One quick question. Did you delete all your previously generated classes before generating entities and DAO’s again?
From the above screen shot, I notice that you can safely remove the package be.tradelec.model.
Can you remove the package and do the generation again?
Let me know if you still have the issue.

I even created a new a project every time so there was no need to delete the previous sources. (checking the include files box when deleting of course)

I’m using the latest download of MyEclipse 7.5 and MySQL client version: 5.0.51a

The mysql connector jar seems to be another version though:
mysql-connector-java-5.1.7-bin

Can’t seem to download your version of the connector but I can retry with the 5.1.10 version which now seems to be the latest.

Tomorrow I will take my personal laptop to work and will try again with my laptop…

Thanks already for all the help, will keep you informed here.

Kind regards,

Jochen

[Dr.Drane]

Are you perhaps using XAMPP for the mysql database or a stand alone version?

[Dr.Drane]

And did you use the database script I pasted here or did you recreate it yourself?

[Dr.Drane]

Just did a retry with latest version of XAMPP + latest version of the connector jar.

Also I now used a version of eclipse with MyEclipse 7.5 plugged in, instead of a standalone MyEclipse.

But still same problem.

Do you also have a MyISAM database with a MyISAM “user_has_language” table, and the “language” and “user” tables in InnoDB?

Thanks and greets

[support-shalini]

Jochen,
I will escalate this issue to the dev team.
May be they can help you out.

[Dr.Drane]

Thank you Shalini!

I’ve sent you a private message here too.
Did you perhaps already have the time to read it?

Kind regards,

Jochen

[Loyal Water]

Jochen,
Im afraid the persistence team is still looking into this and they haven’t got back to me with a reply yet. We will try and update you soon.

[Unmesh Kulkarni]

Hi Support Team/Jochen,

Did you find a resolution to this problem? I am running into the same issue and would appreciate quick help. I am using MySQL 5, MyEclipse 7.5, Hibernate 3.2.6 GA through JPA and Java 6.

Here’s my problem (the sql is attached at the end for reference):

I have two entities, ROLE and GROUP. They have a many-to-many relationship. i.e. a GROUP consists of many ROLE’s and a ROLE can be a part of many GROUP’s. I created tables for ROLE and GROUP, and another one for ROLE_GROUP_MAPPING. The PK for the ROLE_GROUP_MAPPING is the combination of ROLE_ID and GROUP_ID.

When I reverse engineer the code, I get a class for RoleGroupMapping. Generated code for Role and Group classes each has a Set of RoleGroupMapping object. This is not what I expect to happen. The right way to handle this situation would be for Role to have a Set of Groups and vise-versa.

When can I see this fixed?

Second, related, question: I suspect one can control the generated class structure through jpa.reveng.xml. But where is the specification of the format for this file? I would like to know all options I can specify in that file. So is there a DTD or schema for this file that I can refer to?

Thanks,
Unmesh

SQL:

create table groupinfo (
  group_id                                integer not null auto_increment,
  group_name                            varchar(20) unique not null,
  remarks                                varchar(80),
  creation_date                           timestamp(8)                 not null default '2009-10-10 00:00:00',
  primary key (group_id)
) TYPE=InnoDB;

create table roleinfo (
  role_id                                integer not null auto_increment,
  role_name                                varchar(20) unique not null,
  remarks                                varchar(80),
  creation_date                           timestamp(8)                 not null default '2009-10-10 00:00:00',
  primary key (role_id)
) TYPE=InnoDB;

-- Many-to-many mapping of Roles and Groups
create table role_group_mapping (
  role_id                                 integer,
  group_id                                integer,
  creation_date                           timestamp(8)                 not null default '2009-10-04 00:00:00',
  primary key (role_id, group_id),
  foreign key (group_id)                 references groupinfo(group_id),
  foreign key (role_id)                 references roleinfo(role_id)
) TYPE=InnoDB;

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