Hi all,

these are actually two separate questions.

First is about expressions. Suppose i have two entities, A and B. A has pk 
'aid' and fk (non-mandatory) 'bid'. B has pk 'bid'.
I want to build two separate expressions for A like those (1) 'aid=1' and (2) 
'bid=2'. Since 'aid' and 'bid' are not properties of A class, statements like 
this: 
Expression.fromString("aid=1") results in exception. With 'bid' the sutiation 
is event harder, because while i write something like 'b.bid=2', b relation 
target might event not exist.
I know i can do this using 'db:' prefix, but this is not a solution for me, 
because i'm using ROP and 'db:' do not work on client since DBEntities are not 
being sent through hessian.
So how i can create such queries (note than i prefer using SelectQuery, because 
there might be other qualifiers in my expression)??

Other thing i discovered about expresions is they are type-dependent, so that 
if 'count' is integer property, Expression.fromString("count='1'").match(...) 
(note quotes here!) will never work because it will search for string 'count' 
property. This is no good because all databases i know support such automatic 
type conversion. So SelectQuery will work ok, but simple match() will not. 
Reading comments in 'ASTEqual', 'ASTLess' and other, i saw i'm not the first to 
ask this. But i think this is quite easy to implement (at least converting from 
String to Number), so i'd ask for this feature.
==========
Second, about state of objects. 
I create new transient object 'A' and then set some EXISTING relation target of 
B class: 

//b is persistent in db and fetched using SelectQuery or something else
A a = new A();
a.setB(b);

The reason i do this is somewhat like the previuos question in the list. I need 
to persist objects only when user presses 'Save', not when my data object is 
created.

So, when i do this, several things occur. First, 'b' state is changed to 
MODIFIED since relationship affects both sides. But note that 'b' now refers to 
unexisting and non-'NEW' object. Second, a's temp id is added to 
ObjectContextStateLog's dirtyIds!
So right now these functions will definitely crash in NPE:
-context.commitChanges()
-context.newObjects,
since temp id presents in dirtyIds but node is not registered in GraphManager.

In my local version of cayenne i managed to do some workaround by changing 
ObjectContextStateLog and ObjectContextChangeLog so that they will not mark 
dirty anything while working with transient objects. However, probably 
context.registerObject(a) will not work correctly, but i don't need that, 
instead i create 'new' object and fill it with 'transient' one properties:
A a2 = (A)context.newObject(A.class);
a2.setB(a.getB())
context.commitChanges().

This works fine for me, but i think something must be done around collapsing 
'transient' and 'in-scope' (registered) objects.

Thanks,
Andrey)

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