Auto-increment Pickle
Hello all,
I seem to a few choices I have to make to skirt around some issues with using the auto-increment methods of DBs. Here's my problem:
Consider the following CMP bean snippet including the xdoclet code:
/**
* @author janderson
*
* @ejb.bean
* display-name = "Ticket EJB"
* description = "Getters and setters for tickets"
* name = "Ticket"
* view-type = "local"
* jndi-name = "ejb/CallCenter/Core/Ticket"
* type = "CMP"
* cmp-version = "2.x"
* primkey-field = "ID"
* schema = "TICKET"
* @ejb.persistence
* table-name = "TICKET"
* @jboss.persistence
* create-table = "true"
* table-name = "TICKET"
* @ejb.finder
* query = "Select Object(o) FROM TICKET o"
* signature = "java.util.Collection findAll()"
* unchecked = "true"
*
*/
public abstract class TicketBean implements EntityBean {
/**
* This class will hold generic TicketBean information.
*/
public TicketBean() {
super();
}
/**
* @ejb.persistence
* column-name = "ID"
* jdbc-type = "BIGINT"
* sql-type = "BIGINT"
*
* @jboss.persistence
* auto-increment = "true"
* not-null = "true"
* @ejb.interface-method
* @return
*/
public abstract Long getID();
public abstract void setID(Long ID);
/**
* @ejb.persistence
* column-name = "DESCRIPTION"
* jdbc-type = "VARCHAR"
* sql-type = "VARCHAR(100)"
* @jboss.persistence
* not-null = "true"
* @ejb.interface-method
* @return
*/
public abstract String getDesc();
/**
* @ejb.interface-method
* @param Desc
*/
public abstract void setDesc(String Desc);
/**
* @ejb.create-method
* @param s
* @throws CreateException
*/
public Long ejbCreate(String s) throws CreateException{
setDesc(s);
return null;
}
This code basically creates a CMP bean with two fields. Now check out the ejbCreate() method again. It only set's the Desc field, not the ID field wich is the primary key! The database system should be providing the Primary Key field through the <auto-increment/>. Every time I create a new bean, a new record in the database is created and the Primary key is there and incremented. However, I get a Nullpointerexception because the container has no way of knowing that the primary key of the record I just set is not null.
Anyway, I'm positive I'm not the first to run into this sort of thing. Here are my proposed solutions.
1) Write a session bean to keep track of primary keys and generated auto-incremented primary keys. But this seems like a lot of work re-writing an auto-increment system when I could just use the host RDBMS's.
2.)Write a bean that implements methods in the JDBC drivers to determine what the next auto-incremented number in a table would be. This would seriously hinder database indepence.
Is there some other way that I'm just not seeing? Is there a way to allow records to be committed with unknown primary keys? What about null primary keys?
I'm half-sure there could be a simple solution to this, but I haven't found it yet. Half of what I read suggested just writing your own auto-increment system.
