Igor>but you can create a testcase, reproducing the bare bits of code in a
testcase just like you did in the email below. the advantage would be
that i would have something i can play with which makes it much easier
to find the problem.
I will work on a quick start tonight, when I'm not at work. But here's what I'd
like to do, possibly extending Metagen. I have a Report object which includes
an abstract Document object. Document has 3 concrete subclasses, Book,
Article, and Monograph. I have FormComponentPanels for each, which I'd like to
swap in and out. I've used Metagen to create ReportMeta, DocumentMeta,
BookMeta, etc. I'd like to extend Metagen so I can write code like
IModel<Book> bookModel =
MetaModel.of(report).get(ReportMeta.document).as(Book.class);
and
IModel<String> isbnModel =
MetaModel.of(report).get(ReportMeta.document).as(Book.class).get(BookMeta.isbn);
Since I don't want to modify the MetaModel class on my own, I've written a
SubClassModel class like so:
private static class SubClassModel<T> extends MetaModel<T> {
private static final long serialVersionUID =
3511732306311269529L;
public SubClassModel(MetaModel<? super T> superModel, Class<T>
clazz) {
super(superModel);
}
@Override
public T getObject() {
return (T) super.getObject();
}
@Override
public void detach() {
super.detach();
}
public static <T> MetaModel<T> as(MetaModel<? super T>
superModel, Class<T> clazz) {
return new SubClassModel<T>(superModel, clazz);
}
}
}
Unfortunately, when the validation system gets its hands on this, it throws a
NPE as it adds the property validators:
Caused by: java.lang.NullPointerException
at
net.ftlines.wicket.validation.bean.ReflectableProperty.init(ReflectableProperty.java:46)
at
net.ftlines.wicket.validation.bean.ReflectableProperty.<init>(ReflectableProperty.java:98)
at
net.ftlines.wicket.validation.bean.ModelPropertyResolver.resolve(ModelPropertyResolver.java:35)
at
net.ftlines.wicket.validation.bean.ValidationContext.resolveProperty(ValidationContext.java:80)
at
net.ftlines.wicket.validation.bean.ValidationForm$1.component(ValidationForm.java:170)
at
net.ftlines.wicket.validation.bean.ValidationForm$1.component(ValidationForm.java:163)
at org.apache.wicket.util.visit.Visits.visitChildren(Visits.java:143)
at org.apache.wicket.util.visit.Visits.visitChildren(Visits.java:161)
at org.apache.wicket.util.visit.Visits.visitChildren(Visits.java:122)
at
org.apache.wicket.MarkupContainer.visitChildren(MarkupContainer.java:908)
at
net.ftlines.wicket.validation.bean.ValidationForm.addPropertyValidators(ValidationForm.java:162)
at
net.ftlines.wicket.validation.bean.ValidationForm.onBeforeRender(ValidationForm.java:155)
at org.apache.wicket.Component.internalBeforeRender(Component.java:981)
at org.apache.wicket.Component.beforeRender(Component.java:1015)
at
org.apache.wicket.MarkupContainer.onBeforeRenderChildren(MarkupContainer.java:1785)
... 52 more
This happens when Model is that SubclassModel<Book>.
How would you use Metagen for this case? Is it worth extending it?
Respectfully,
Eric Jablow
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