Daos can be useful in certain contexts. In particular, if you have
some means of automagically generating the dao. :)
For instance, on a Tapestry5 + hibernate-based project I'm working on
right now, there's a DaoSource service.
What's more, is there's an..njectDao annotation that plays nicely
with T5's pages and components.
So you can do something like:
@InjectDao(User.class)
Dao<User> userDao;
public List<User> getAllUsers() {
return userDao.listAll();//or something like this.
}
The key piece being the fact that Dao<User> wasn't code you have to
write (or even generate).
It can make things convenient, but, like Michael and John, I tend away
from Dao's.
Robert
On Mar 30, 2010, at 3/304:26 PM , John Armstrong wrote:
> My latest project has a lot of DAO going on and while it made sense
> (for
> some reason, habit?) at first I regret going that way and will, over
> time,
> be migrating into the same pattern that Michael highlights. Its
> really just
> a big useless layer for all the reasons he highlights, at least in my
> context.
>
> John-
>
> On Tue, Mar 30, 2010 at 2:20 PM, Michael Gentry
> <mgentr..asslight.net>wrote:
>
>> Hi Mike,
>>
>> I personally tend to not create DAOs for Cayenne. If I need a
>> findBy*
>> type method, I just add it to the Cayenne-generated class as a static
>> method. (For example, I have a User.withUsernameAndPassword() static
>> method in my User class.) For findById, you can use DataObjectUtils
>> directly if you like:
>>
>> http://cayenne.apache.org/doc/api/org/apache/cayenne/DataObjectUtils.html
>> (objectForPK)
>>
>> Of course, this is just what I tend to do. Your mileage and that of
>> others will likely vary. To me, part of the concept of the DAO is
>> that you can transparently and magically change the DAO code to use a
>> different ORM and if everything else is using the DAOs, it'll all
>> just
>> work. Of course, the assumes that every single ORM works exactly the
>> same way (they don't) and it also means you are choosing your ORM for
>> failure (because you expect the need to swap them out). Cayenne
>> works
>> differently than Hibernate which works differently than other
>> ORMs. I
>> choose an ORM for the features it gives me. To me it doesn't make as
>> much sense to code with the DAOs (especially when they limit the use
>> of your ORM), but I'm sure others will disagree with me. :-)
>>
>> mrg
>>
>>
>> On Tue, Mar 30, 2010 at 4:51 PM, <MGargan..scholar.com> wrote:
>>> When using Cayenne are DAO's still the pattern used for findAll,
>>> findByProperty, and findById query methods or is there some better
>>> way to
>>> do this in Cayenne? For example in the pet store project I see
>>> DAO's
>>> being implemented, but I know that example was taken from other
>>> projects
>>> that use DAO's to begin with so I'm not sure if it was just
>>> retrofitted
>> to
>>> use DAO's with Cayenne. I tried to look at some other examples
>>> from the
>>> website, but most of those are either not complex enough to
>>> warrant that
>>> kind of structure or the links are dead. I hope this is
>>> clear. :) Also
>>> if DAO's are the recommended pattern to use is there a tool (i.e.
>>> eclipse
>>> plugin) that will generate them?
>>>
>>> Thanks.
>>> -Mike
>>>
>>
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