> So I'm a little confused about how the EJB 2.0 relations are represented
> in the db. I know that JBoss (my app server) creates an additional
> attribute for a relation in the table if it is specified in the xml file
> under relationships (ie user has one-to-one with contact info, db
> creates USER_CONTACTINFO_PKUSERNAME in user and
> CONTACTINFO_PKCONTACTINFOID in contact info so that they point to each
> other). That means, and please tell me if this is correct, I do not need
> to have attribute fields in my beans for representing foreign keys (ie
> user has pkusername, and and I don't need to put in there a
> FKContactInfo explicitly).
you're assumption is correct. the CMP2 engine handles this for you.
> Second, how do local interfaces work? Here is the actual scenario I'm
> working with. 2 tables, book and course. A 'Book' has a 'course' that
> may or not exist. I made 'course' a Local Interface for a 'book'. If the
> course already exists in the db, how do I create a book with a course?
> Normally I call create() with a param that has both a book and a course
> in it, and it calls the helper method create course to make the course
> instance and call 'setcourse()'. Now am I creating a real course in the
> database (and it MAY OR MAY NOT exist in the db already), or is it
> simply making a local interface so he can refer to the the right row in
> the db? should i maybe call findbyprimarykey in the createcourse below?
> I recall my trace said once that the row already exists in the db.
yep... create will insert a record into the database. if you know the record already
exists, you should be using findByPrimaryKey
> public void ejbPostCreate(BookValueObject Book,
> CourseValueObject Course,
> DepartmentValueObject Department)
> throws CreateException{
> CourseLocal myCourseLocal = createCourse(Course, Department);
> setCourse(myCourseLocal);
> }
>
>
> private CourseLocal createCourse(CourseValueObject CourseView,
> DepartmentValueObject DepartmentView){
> try{
> InitialContext initial = new InitialContext();
> CourseLocalHome home = (CourseLocalHome)
> initial.lookup("java:comp/env/ejb/Course");
> return home.create(CourseView,DepartmentView);
> } catch (Exception e) {
> throw new javax.ejb.EJBException(e);
> }
> }
I'm not sure what you're trying to do, but if you're saying that you may or may not
have it in the database - you dont care, but you
want to make sure it exists in the database at the end of the method, and that you
have a reference to it, you should do something
like:
private CourseLocal findOrCreate(CourseValueObject courseView,
DepartmentValueObject deptView)
{
try
{
return courseHome.findByPrimaryKey(...);
}
catch (ObjectNotFoundException e)
{
try
{
return courseHome.create(courseView, deptView);
}
catch (CreateExcpetion e)
{
throw new EJBException(e.getMessage());
}
}
catch (FinderException e)
{
throw new EJBException(e.getMEssage());
}
}
> In addition, have I specified something wrong in code or xml dd?,
> because for one creation of a table jboss 3.0 seems to be doing too many
> transactions here (insert a user, delete him cause for some reason the
> info was done wrong the first time, insert his contact info, delete it
> cause its wrong for some reason, then insert the correct ones for both.
> Very odd!
>
> INSERT INTO USER VALUES('eric','open','2002-03-10','bird',NULL,
> '2002-03-10','normal',NULL)
> INSERT INTO CONTACTINFO VALUES
> (0,'','','etree',NULL,'','','','',0,'','','','',NULL)
> DELETE FROM CONTACTINFO WHERE PKCONTACTINFOID=0 AND TELEPHONENUMBER=''
> AND ADDRESSFIRST='' AND EMAIL='etree' AND FKUSERNAME=NULL AND
> FIRSTNAME='' AND CITY='' AND ADDRESSSECOND='' AND POSTALCODE='' AND
> FKHOUSINGUNITID=0 AND COUNTRY='' AND LASTNAME='' AND STATE='' AND
> MIDDLENAME='' AND USER_CONTACTINFO_PKUSERNAME=NULL
> INSERT INTO CONTACTINFO VALUES
> (0,'','','etree',NULL,'','','','',0,'','','','','eric')
> DELETE FROM USER WHERE PKUSERNAME='eric' AND ACCOUNTSTATUS='open' AND
> EXPIRATIONDATE='2002-03-10' AND PASSWORD='bird' AND RELIABILITY=NULL AND
> LOCKDATE='2002-03-10' AND ACCOUNTTYPE='normal' AND
> CONTACTINFO_PKCONTACTINFOID=NULL
> INSERT INTO USER VALUES('eric','open','2002-03-10','bird',NULL,
> '2002-03-10','normal',0)
I'm not quite sure what you're asking here....
> Sorry for the amount of content in this message. Please answer as many
> questions as soon as possible( mainly the recreate question and the key
> question) , I really need the help.
(o:
cheers
dim
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