This is a continuation of some prior posts where I am trying to implement a real-world application with a complex data model using JPAContainer, etc.
I am working on displaying various parts of the main Entity that also shows a few of it’s association data… some of this association data itself has associated data, etc.
Some of these associations are OPTIONAL (and are annotated that way in the @OneToOne) –
However, when I try to use that type of nested property in a Form, via a FieldGroup I get an NPE at :
Caused by: com.vaadin.data.util.MethodProperty$MethodException
at com.vaadin.data.util.NestedMethodProperty.getValue(NestedMethodProperty.java:205)
at com.vaadin.data.util.TransactionalPropertyWrapper.getValue(TransactionalPropertyWrapper.java:73)
at com.vaadin.ui.AbstractField.getDataSourceValue(AbstractField.java:301)
at com.vaadin.ui.AbstractField.setPropertyDataSource(AbstractField.java:626)
… 44 more
Caused by: java.lang.NullPointerException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:601)
at com.vaadin.data.util.NestedMethodProperty.getValue(NestedMethodProperty.java:201)
The usage is :
ourLayout.addComponent( fieldGroup.buildAndBind( “Offense Type”, “arrestInfo.offenseTypeItem.itemText” ), 2, 8, 3, 8 );
And yes, the bean data for arrestInfo.offenseTypeItem is null – which is acceptable, it’s allowed to be null since it’s optional …
I don’t think Vaadin should throw a NPE –
What I think would be very very slick is if Vaadin accepted the ?. Groovy type annotation (arrentInfo?.offenseTypeItem?.itemText) that indicates to just return a null if any of the path is null …
But even still, I would think the logic in the NestedMethodProperty.class could just protect this too and return null …
@Override
public T getValue() {
try {
Object object = instance;
for (Method m : getMethods) {
object = m.invoke(object); <--- Line throwing the NPE
}
return (T) object;
} catch (final Throwable e) {
throw new MethodException(this, e);
}
}Something simple like:
…
Object object = instance;
for (Method m : getMethods) {
object = m.invoke(object);
if ( null == object )
return (T) object ;
}
…
Anyway – meanwhile – any ideas on how to protect this from happening cleanly? I have about 15 fields on this one form alone that have optional associations …
Thanks!