I don't think this is the TAP5-733 bug. Running the code I've recreated the
exception and yes, Blackbird reported it as a communication error, but the log
shows Its root cause was an NPE caused by _personHolders being null.
Caused by: java.lang.NullPointerException
at
jumpstart.web.pages.examples.tables.AjaxFormLoop1New.onAddRow(AjaxFormLoop1New.java:106)
at
jumpstart.web.pages.examples.tables.AjaxFormLoop1New.dispatchComponentEvent(AjaxFormLoop1New.java)
at
org.apache.tapestry5.internal.structure.ComponentPageElementImpl.dispatchEvent(ComponentPageElementImpl.java:902)
at
org.apache.tapestry5.internal.structure.ComponentPageElementImpl.triggerContextEvent(ComponentPageElementImpl.java:1081)
... 68 more
I think it's due to the conversation id never appearing in the page context.
Try this change to onActivate() - when you start a conversation redirect to the
same page so that onPassivate() gets called and therefore the conversation id
goes into the URL.
Object onActivate(EventContext context) throws Exception {
if (context.getCount() == 0) {
setupPersonHolders();
_conversationId = startConversation(_personHolders);
return this;
}
else {
_conversationId = context.get(String.class, 0);
_personHolders =
getPersonHoldersFromConversation(_conversationId);
if (_personHolders == null) {
setupPersonHolders();
_conversationId =
startConversation(_personHolders);
return this;
}
}
return null;
}
Also, don't get in the habit of initialising fields in the declaration, eg.
> private String _conversationId = null;
The reason is that you'll rarely get a freshly instantiated page - more likely
is you'll get one that Tapestry has pulled out of its pool of page instances.
Cheers,
Geoff
On 14/03/2010, at 2:11 PM, Greg Pagendam-Turner wrote:
> Guys,
>
> I'm trying to work out how to fix the AjaxFormLoop example in Jump Start.
>
> http://jumpstart.doublenegative.com.au:8080/jumpstart/examples/tables/ajaxformloop1
>
> The code recommends that it should use conversations instead of session
> persistence. I've changed the code to use conversations but still get
> the hidden from field element error when clicking the "Add Row" link as
> mentioned in the JIRA https://issues.apache.org/jira/browse/TAP5-733.
>
> This is because there is nothing in the rendered partial xml that
> contains a tag that the hidden field can be placed after (such as input,
> select, textarea, label, p, div, td or li).
>
> Stepping through the code shows that the markup retruned when clicking
> Add Row is just:
> <ajax-partial></ajax-partial>
>
> I'd appreciate any clues on where to look next please.
>
> Regards,
>
> Greg.
>
> PS: Modified AjaxFormLoop1.java is
>
> package jumpstart.web.pages.examples.tables;
>
> import java.text.DateFormat;
> import java.text.Format;
> import java.util.ArrayList;
> import java.util.List;
> import java.util.Locale;
>
> import jumpstart.business.domain.examples.Person;
> import jumpstart.business.domain.examples.iface.IPersonServiceLocal;
> import jumpstart.client.IBusinessServicesLocator;
> import jumpstart.web.commons.Conversation;
> import jumpstart.web.commons.Conversations;
> import jumpstart.web.commons.ExceptionUtil;
> import jumpstart.web.pages.Index;
> import jumpstart.web.pages.examples.wizard.WizardUsingComponents.Step;
> import jumpstart.web.state.examples.wizard.CreditRequest;
>
> import org.apache.tapestry5.BindingConstants;
> import org.apache.tapestry5.ComponentResources;
> import org.apache.tapestry5.EventContext;
> import org.apache.tapestry5.ValueEncoder;
> import org.apache.tapestry5.annotations.Component;
> import org.apache.tapestry5.annotations.InjectPage;
> import org.apache.tapestry5.annotations.Parameter;
> import org.apache.tapestry5.annotations.Persist;
> import org.apache.tapestry5.annotations.Property;
> import org.apache.tapestry5.annotations.SessionState;
> import org.apache.tapestry5.corelib.components.Form;
> import org.apache.tapestry5.ioc.annotations.Inject;
>
> public class AjaxFormLoop1 {
> private String _conversationId = null;
>
> @SessionState
> private Conversations _conversations;
>
> // We've used "session" persistence but it is risky. Better
> techniques include wrapping this field in a
> // Conversation (see the Wizard examples) or persisting it in the
> database.
> @Parameter(defaultPrefix = BindingConstants.PROP)
> @Property
> //@Persist
> private List<PersonHolder> _personHolders;
>
> @SuppressWarnings("unused")
> @Property
> private PersonHolder _personHolder;
>
> private List<Person> _persons;
>
> @Component(id = "personsedit")
> private Form _form;
>
> @Inject
> private IBusinessServicesLocator _businessServicesLocator;
>
> @InjectPage
> private AjaxFormLoop2 _page2;
>
> @Inject
> private Locale _currentLocale;
>
> @Inject
> private ComponentResources _resources;
>
> Object[] onPassivate() {
> return new Object[] { _conversationId };
> }
>
> Object onActivate(EventContext context) throws Exception {
> if (context.getCount() == 0) {
> setupPersonHolders();
> _conversationId = startConversation(_personHolders);
> }
> else
> {
> _conversationId = context.get(String.class, 0);
> }
>
> _personHolders = getPersonHoldersFromConversation(_conversationId);
>
> return null;
> }
>
> void setupPersonHolders()
> {
> // Get all persons - ask business service to find them (from
> the database)
> _persons = getPersonService().findPersons();
>
> _personHolders = new ArrayList<PersonHolder>();
> for (Person person : _persons) {
> _personHolders.add(new PersonHolder(person, false,
> person.getId()));
> }
> }
>
> // Form triggers the PREPARE event during form render and form
> submission.
>
> void onPrepare() {
> if (!_form.getHasErrors()) {
> if (_personHolders == null) {
> //setupPersonHolders();
> _personHolders =
> getPersonHoldersFromConversation(_conversationId);
> }
> }
> }
>
> PersonHolder onAddRow() {
> // Create a skeleton Person and add it to the displayed list
> with a unique key
> Person newPerson = new Person();
> PersonHolder newPersonHolder = new PersonHolder(newPerson,
> true, 0 - System.nanoTime());
> _personHolders.add(newPersonHolder);
>
> return newPersonHolder;
> }
>
> void onRemoveRow(PersonHolder personPlus) {
> int index = _personHolders.indexOf(personPlus);
> PersonHolder holder = _personHolders.get(index);
>
> // If the person is new, remove them from the list. Else, flag
> them to be deleted from the database.
> if (holder.isNew()) {
> _personHolders.remove(personPlus);
> }
> else {
> holder.setDeleted(true);
> }
> }
>
> void onValidateForm() {
> List<Person> personsToCreate = new ArrayList<Person>();
> List<Person> personsToChange = new ArrayList<Person>();
> List<Person> personsToDelete = new ArrayList<Person>();
>
> for (PersonHolder holder : _personHolders) {
> if (holder.isNew()) {
> personsToCreate.add(holder.getPerson());
> }
> else if (holder.isDeleted()) {
> personsToDelete.add(holder.getPerson());
> }
> else {
> personsToChange.add(holder.getPerson());
> }
> }
>
> System.out.println(">>> personsToCreate = " + personsToCreate);
> System.out.println(">>> personsToChange = " + personsToChange);
> System.out.println(">>> personsToDelete = " + personsToDelete);
>
> try {
> // In a real application you would persist them to the
> database instead of printing them
> // getPersonService().bulkEditPersons(personsToCreate,
> personsToChange, personsToDelete);
> }
> catch (Exception e) {
> // Display the cause. In a real system we would try harder
> to get a user-friendly message.
> _form.recordError(ExceptionUtil.getRootCause(e));
> }
> }
>
> Object onSuccess() {
> List<Person> persons = new ArrayList<Person>();
> for (PersonHolder holder : _personHolders) {
> if (!holder.isDeleted()) {
> persons.add(holder.getPerson());
> }
> }
> _page2.set(persons);
> endConversation(_conversationId);
> _resources.discardPersistentFieldChanges();
> return _page2;
> }
>
> void onRefresh() {
> _resources.discardPersistentFieldChanges();
> onPrepare();
> }
>
> Object onActionFromGoHome() {
> _resources.discardPersistentFieldChanges();
> return Index.class;
> }
>
> @SuppressWarnings("unchecked")
> public ValueEncoder getEncoder() {
> return new ValueEncoder<PersonHolder>() {
>
> public String toClient(PersonHolder value) {
> Long key = value.getKey();
> return key.toString();
> }
>
> public PersonHolder toValue(String keyAsString) {
> Long key = new Long(keyAsString);
> for (PersonHolder holder : _personHolders) {
> if (holder.getKey().equals(key)) {
> return holder;
> }
> }
> throw new IllegalArgumentException("Received key \"" + key
> + "\" which has no counterpart in this
> collection: " + _personHolders);
> }
> };
> }
>
> public class PersonHolder {
> private Person _person;
> private Long _key;
> private boolean _new;
> private boolean _deleted;
>
> PersonHolder(Person person, boolean newPerson, Long key) {
> _person = person;
> _new = newPerson;
> _key = key;
> }
>
> public Person getPerson() {
> return _person;
> }
>
> public Long getKey() {
> return _key;
> }
>
> public boolean isNew() {
> return _new;
> }
>
> public boolean setDeleted(boolean deleted) {
> return _deleted = deleted;
> }
>
> public boolean isDeleted() {
> return _deleted;
> }
> }
>
> private IPersonServiceLocal getPersonService() {
> // Use our business services locator to get the EJB3 session
> bean called "PersonServiceLocal".
> return _businessServicesLocator.getPersonServiceLocal();
> }
>
> public Format getDateFormat() {
> return DateFormat.getDateInstance(DateFormat.SHORT,
> _currentLocale);
> }
>
> private String startConversation(Object target) {
> String conversationId = Long.toString(System.currentTimeMillis());
> _conversations.add(new Conversation(conversationId, target));
> return conversationId;
> }
>
> private void endConversation(String conversationId) {
> _conversations.remove(conversationId);
>
> // If conversations ASO is now empty then remove it from the
> session
>
> if (_conversations.isEmpty()) {
> _conversations = null;
> }
> }
>
> private List<PersonHolder> getPersonHoldersFromConversation(String
> conversationId) {
> Conversation conversation = _conversations.get(conversationId);
> if (conversation != null&& conversation.getTarget() instanceof
> List<?>) {
> return (List<PersonHolder>) conversation.getTarget();
> }
> return null;
> }
>
> }
>
>
>
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