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From "Stevan Buzejic" <>
Subject Help for a student project - master studies
Date Sun, 11 Sep 2011 19:27:48 GMT

My name is Stevan Buzejińá, a master student of software engineering at the
Faculty of organizational sciences in Belgrade, Serbia. I am working on a
research project that involves Your framework, NakedObjects or
ApacheIsis(for the Java platform). 
I have learned the basic concepts of NakedObjects, made a few simple use
cases and have decided to try something a bit more complex. 
Namely, I have a strong object and a weak object and what I would like to
do, is make a more complex form for the strong object (in my concrete case,
the strong object is named Customer) that allows us to immediately add weak
objects to it (in my case, weak objects are Invoices). Specifically, what I
would like is to be able to add weak objects to a temporary list and after
clicking the Save button for the strong object, I would like to save
everything to the database with all the relationships correctly created and

I have managed to create Customer and Invoice classes and all relationships
between them (Using mutual registration patern). But then the problem
arises. I am using dnd viewer. When Ii press right click on a Customer and
select new Customer option I want to add to that cutomer an Invoice. So I
press right click on mouse and select new Invoice (similar use case like
CarService application example from the book Domain driven design using
Naked Objects, when I want to add a car to a customer). After that I fill
the form for creating new Invoice with some data and press save button.
Everithing it's ok. But now I want to save my Customer. When I press the
save button on a Customer form exception arises:


Object already persistent:


etc. I know why it is happening, the Customer is saved when I save the
Invoice, so when I hit save on Cusotmer form it tries to save it again but
this customer is already persisted. Is there any techique to avoid this
problem or any example on web where I can find solution for this? I know how
to achieve this using conventional programming and various technologies, but
I am not sure if and how it can be done with Your framework. Currently I am
reading Your book "Domain driven design using Naked Objects", and I haven't
managed to find the resources needed to solve my problem and are hoping You
can help me with tips and/or instructions.

I thank You in advance for any help You can give me it would be significant
to my work.

Stevan Buzejic


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