I agree with Thiago: "My best practices for persisting fields is this: just do
it when there's no way of avoiding it."
Most JumpStart examples avoid @Persist. The reasons are given in the "Caution"
section of this page:
http://jumpstart.doublenegative.com.au/jumpstart7/examples/state/storingdatainapage
In T5.3, you need persistence to avoid losing certain fields, eg. hidden
fields, when a Form is in error. That's because it redirects and the
ValidationTracker only looks after the input-capable fields. You'll see
JumpStart for T5.3handling it with flash persistence.
T5.4 is much simpler: you no longer need persistence because it doesn't
redirect (on Form error).
As for AjaxFormLoop, which I don't like either, here are three examples that do
not use @Persist. Like Lance's suggestion, they use an encoder:
http://jumpstart.doublenegative.com.au/jumpstart/examples/ajax/formloop1
http://jumpstart.doublenegative.com.au/jumpstart/examples/ajax/formloopwithholders1
http://jumpstart.doublenegative.com.au/jumpstart/examples/ajax/formlooptailored1
Geoff
On 15 Aug 2014, at 8:16 pm, Lance Java <lance.j...@googlemail.com> wrote:
> 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
