initialize them lazily just like the model would
private transient Foo foo;
private Foo getFoo() { if (foo==null) { foo=...; } return foo; }
-igor
On Fri, Nov 20, 2009 at 10:54 AM, wrote:
> Hi
>
> It appears that I am fighting against the framework that limits my
> choices when I start using LDMs (LoadableDetachableModel).
>
> Many examples in the framework documentation don't use LDMs. For
> simplicity, they assume that the domain object e.g. person is
> available to a model in an instance variable.
>
> But LDM use is Wicket best practice. So if I switch to LDMs, then I
> remove instance variables containing domain objects to avoid their
> leakage into the session.
>
> As a consequence of that, I must use wrapped PropertyModels that use
> reflection and that are not refactor safe.
>
> In addition, in onSubmit() methods, I have to manually extract the
> domain object from the model.
>
> If I use simple custom models per form field, overriding
> org.apache.wicket.model.Model with inner classes, then I have to
> manually extract the domain object from the LDM for each
> setObject(...) and getObject() method.
>
> To avoid these obstacles I would keep for convenience a transient
> instance of the domain object. In onDetach(), I would set it to null
> to avoid leakage into the session.
>
> But how do I initialize it? I can do it in a Panel's constructor, but
> in a stateful page, the constructor of a Panel is not called when it
> is taken out of the session.
>
> I found Page.onPageAttached() interesting for that, but I cannot use
> it with a Panel sub class that is not hard-wired into the Page.
>
> How can I use LDMs without this conflict? In the described scenario,
> Wicket is really difficult to use, and that is because one has to be
> so careful about domain objects leaking into the session.
>
> Many thanks
>
> Bernard
>
>
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