This is my first hibernate project. I"m building a simple user type web system. I have a Person.java class and a PaymentType.java class.
A Person object has fields like id, name, email, and PaymentType which is my own type or object, not a string or int. I want to be able to have one person have multiple payment types. I am no db expert so the if that it one-to-many , i don't know, i may be wrong. I am using a join table 'personpayment' . I cannot figure out how to do this. My main problem is the paymenttype field in the person object. I want to be able to get a set of paymenttypes in the person object for that field.
example:



what am i doing wrong?? I get mapping exception: An association from the table person payment refers to an unmapped class: java.util.Set

Hibernate version: 3

Mapping documents:

<------------------- this is for Person.java--------------------->



<------------------- this is for PaymentType.java------------->

</hibernate-mapping>


<---------- here is my table structures --------------------->

CREATE TABLE `paymenttype` (
`paymenttype_id` int(9) NOT NULL auto_increment,
`name` varchar(50) default NULL,
`description` text,
PRIMARY KEY (`paymenttype_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 ROW_FORMAT=DYNAMIC COMMENT='InnoDB free: 3072 kB';

/*Table structure for table `person` */

drop table if exists `person`;

CREATE TABLE `person` (
`person_id` int(9) NOT NULL auto_increment,
`fname` varchar(50) default NULL,
`lname` varchar(50) default NULL,
`email` varchar(50) default NULL,
`username` varchar(50) default NULL,
PRIMARY KEY (`person_id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 ROW_FORMAT=DYNAMIC;

/*Table structure for table `personpayment` */

drop table if exists `personpayment`;

CREATE TABLE `personpayment` (
`person_id` int(9) NOT NULL,
`paymentType_id` int(9) NOT NULL,
`startDate` datetime default NULL,
`expiration` datetime default NULL,
`status` tinyint(1) default '0'
) ENGINE=MyISAM DEFAULT CHARSET=latin1 ROW_FORMAT=DYNAMIC COMMENT='InnoDB free: 3072 kB';

Code between sessionFactory.openSession() and session.close():

Full stack trace of any exception that occurs:

Name and version of the database you are using:mySql 5

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:

Your database tables look sensible to me. I would, however, follow the recommendation in the Hibernate literature to add an id column and Java attribute also to the Personpayment table.

You can then map the relationship between Person and Personpayment with the <set ...> mechanism (using inverse="true") in the one-to-many direction, and with the <many-to-one ...> mechanism in the many-to-one direction. Same for the relationship between Payment and Personpayment, although I would consider omitting the inverse mapping for this one.

Concerning your remark about not being a db expert. Most database books have a section about how to proceed from a data model of your problem domain to get a database structure fitting that model. This might give you confidence in the setup of your database. Hibernate just follows this structure, so it can't improve mistakes that have been made in db design.