On Oct 6, Jay Walters quoth:
> I have a stylistic question about EJB design.
Ooh, good. Nothing get's people fighting like style debates.
> Beyond findByPrimaryKey, is it better to have a single finder which
> takes as an argument some type of query object, or a bunch of strongly
> typed finders?
I'd say that if your query can be expressed as a strongly typed finder it
ought to be. That makes for more readable code and allows your compiler
to aid you in the development process more. As with all style issues,
there are always exceptions. You need to weight the benefit of the
following different types of code. (I apologise profusely for the example,
it's all I could quickly think of that would cause this type of
situation.)
#1-
Collection c = home.findItemsThatFitCustomer(currentCustomer);
versus:
#2-
Collection c = home.findItemsSized(currentCustomer.hatSize,
curentCustomer.pantSize, currentCustomer.inseam,
currentCustomer.armLength, currentCustomer.shoeSize);
versus:
#3-
SizeQuery query = new SizeQuery();
query.setHatSize(currentCustomer.hatSize);
query.setPantSize(currentCustomer.pantSize);
query.setInseam(currentCustomer.inseam);
query.setArmLength(currentCustomer.armLength);
query.setShoeSize(currentCustomer.shoeSize);
Collection c = home.findItems(query);
For me *personally* I like the second one which is the strongly typed
version. That makes it clear that the finder only interacts with those
specific types of values and nothing more. It also prevents the 'missing
query element' problem of the third and insulates your Item bean from the
details of the Customer bean (which it doesn't need to know anything
about).
The downside is the explosion of different findXXX() methods but frankly,
once they are written, you only need to make sure they work in one place
as opposed to every time you call it as in #3 or the need to keep your
Customer and your Item bean code insynch as in #1.
Yes, it's a lot more work up front and it's harder(?) to add new queries,
but, like unit testing, it's real benefits come when instead of debugging
all weekend you are at a mate's house with your feet up confident that
your query finds exactly what you're looking for and nothing you're not.
C=)
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Caskey <caskey*technocage.com> /// TechnoCage Inc.
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