Bi-directional relationships create some interesting situations, when
concerned with establishing relationships between two participants. The
following scenario illustrates a problem that I would like vendors to
comment on, if they are up for the challenge.
Assume that SalesRep has a one-to-many bidirectional relationship with
Customer.
------------------
SalesRep rep = SalesRepHome.findByPrimaryKey(somekey);
Customer cust = CustomerHome.create( );
cust.setSalesRep( rep);
Colleciton colleciton = rep.getCustomers( );
if(collection.contains( cust ))
flag = true;
else
flag = false;
-------------------
What is the value of flag? I suspect it should be true in this
scenario.
However, what would happen if the Colleciton of Customer references was
obtained before cust set rep in its salesRep relationship field?
--------------------
SalesRep rep = SalesRepHome.findByPrimaryKey(somekey);
Colleciton colleciton = rep.getCustomers( );
Customer cust = CustomerHome.create( );
cust.setSalesRep( rep);
if(collection.contains( cust ))
flag = true;
else
flag = false;
-------------------------
In this case the flag should still be true, IMO, but it may not for some
containers. The specification warns against modifying a Collection
based relationship field when perusing a Interator of that Collection,
but it doesn't, to my knowledge, address this situation.
Comments?
Richard
--
Richard Monson-Haefel
Author of Enterprise JavaBeans, 2nd Edition (O'Reilly 2000)
Co-Author of Java Message Service (O'Reilly 2000)
http://www.jMiddleware.com
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