On 6/23/07, Flemming Boller <[EMAIL PROTECTED]> wrote:
On 6/23/07, Robert . <[EMAIL PROTECTED] > wrote:
> One thing I am struggling with is where I should put my DAO's and data
> services. I know about the @SpringBean annotation for components, but
> how should I use those in classes such as DetachableXXXModel? Should
> I pass the DAO's I need to that class or should I put DAO's in the
> application object (like Pro Wicket examples do)?
There is no silverbullet here. Each solution has its drawbacks. However
the solution I have come to best like is only using the @SpringBean in
pages, and then pass on the springbean as argument to where every it is
needed. That way it is also more clearly seen in the page where the service
is used.
I'm curious when this is simpler that accessing the DAOs from the
application object. I find it annoying so far that I find out that I need a
certain DAO in my DetachableXXXModel, and then, for example, have to pass it
from the page to the XXXDataProvider, save a reference there, and in the
model method pass it to the DetachableXXXModel.
Is there a good Wicket example project I can look at, besides phonebook,
> that uses Spring and Hibernate? I am interested in the right set-up.
You could also look at the Databinder project. It includes some nice
examples too.
Ok thanks!
I also have some questions about OpenSessionInViewFilter, which probably
> are off-topic, but hope someone wants to help anyway.
>
> There seems to be quite some disagreements about whether using
> OpenSessionInViewFilter is a good thing or not. What does the Wicket
> team/users
> think about it?
I have also used OSIVF on a project. And you really have to be carefull
here. Hibernate has some nasty exceptions that easily will be thrown at you.
Especially Lazyexception session closed or... object with same id is already
loaded in session
Unfortunately I do not know what to be careful for yet :)
I came to the conclusion that is was much easier to copy you hibernate
objects into viewbeans which is designed with wicket in mind. So above the
service layer you have view bean. And under the service layer you have
hibernateobjects (domain objects). I would be happy to hear others comments
on this one.
Do you have an example for this? It's difficult to think of what those
viewbeans are. They don't have associations?
You know the answer(s) to the section below?
If I understand correctly, and please correct me if I'm wrong,
> by using the OpenSessionInViewFilter you get a new transaction at the
> start
> of every request, which commits or rollbacks at the end.
> This is so that lazy associations, which are accessed outside explicit
> transactions,
> such as in Wicket Page classes, are initialized and don't throw an
> exception.
So what kind of transaction exactly is created by the
> OpenSessionInViewFilter?
> (propagation, isolation?)
> Can I use it only for reading?
>
>
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