Thinking about this a bit more, you can probably avoid @Persist by using an
appropriate ValueEncoder.
eg:
<t:ajaxformloop t:id="foos" source="foos" value="foo"
encoder="lazyEncoder">...</t:ajaxformloop>
public class LazyValueEncoder<T> implements ValueEncoder<T> {
private static final String CLIENT_NULL = "XXX";
private ValueEncoder<T> encoder;
private Class<T> type;
public LazyValueEncoder<T>(ValueEncoderSource source, Class<T> type) {
this.encoder = source.getValueEncoder(type);
this.type = type;
}
public String toClient(T value) {
if (value == null) {
return CLIENT_NULL;
}
return encoder.toClient(value);
}
public T toValue(String client) {
if (CLIENT_NULL.equals(client)) {
return type.newInstance();
}
return encoder.toValue(client);
}
}
public class MyPage {
@Property private List<Foo> foos;
@Property private Foo foo;
@Inject private ValueEncoderSource source;
public ValueEncoder<Foo> getLazyEncoder() {
return new LazyValueEncoder(source, Foo.class);
}
public Foo onAddRowFromFoos() {
return null;
}
}
Warning: Untested code
