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https://issues.apache.org/jira/browse/TRINIDAD-1613?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Matthias Weßendorf updated TRINIDAD-1613:
-----------------------------------------
Resolution: Fixed
Fix Version/s: 1.2.14-core
Assignee: Matthias Weßendorf
Status: Resolved (was: Patch Available)
as been applied to 1.2.12.2 branch and trunk;
> Add support for rowKey change
> -----------------------------
>
> Key: TRINIDAD-1613
> URL: https://issues.apache.org/jira/browse/TRINIDAD-1613
> Project: MyFaces Trinidad
> Issue Type: Improvement
> Components: Components
> Affects Versions: 1.2.12-core
> Environment: This is not specific to any environment setup.
> Reporter: Jing Wu
> Assignee: Matthias Weßendorf
> Fix For: 1.2.14-core
>
> Attachments: pk3.patch, pk3.patch
>
>
> RowKey is used in collection model to identify a row, it is safer to use than
> row indicies because RowKeys are unaffected by mutations to the collection.
> But there are cases where a RowKey instance can be changed. The proposal is
> to define a clear way to raise and broadcast such event. The proposal
> contains the following parts:
> 1. RowKeyChangeEvent - This newly introduced event is delivered when row key
> is changed, the event should contain the value for both old row key and the
> new row key.
> 2. RowKeyChangeListener - This is the listener that listens to
> RowKeyChangeEvent, it has method onRowKeyChange() defined. Every time when
> there is an RowKeyChangeEvent event, the implementor of RowKeyChangeListener
> will get notified.
> 3. CollectionModel - The source that detects row key change and raises
> RowKeyChangeEvent and invokes registered listeners.
> Every module that holds reference to rowKey needs to implement
> RowKeyChangeListener, register the listener with CollectionModel. When
> collectionModel detects row key change and there are registered listeners, it
> fires RowKeyChangeEvent to notify all the registered listeners, and the
> affected module will react to the event, update the row key references.
> /**
> * Event that is generated when RowKey changes.
> */
> public class RowKeyChangeEvent extends java.util.EventObject
> {
> /**
> * Creates a new RowKeyChangeEvent
> * @param source the source of the event
> * @param oldRowKey the old row key.
> * @param newRowKey the new row key.
> */
> public RowKeyChangeEvent(
> CollectionModel source,
> Object oldRowKey,
> Object newRowKey)
> {
> super(source);
> _oldRowKey = oldRowKey;
> _newRowKey = newRowKey;
> }
> /**
> * retrieve the old key from the event
> * @return the old key of the event.
> */
> public Object getOldRowKey()
> {
> return _oldRowKey;
> }
> /**
> * retrieve the new key from the event
> * @return the new key of the event.
> */
> public Object getNewRowKey()
> {
> return _newRowKey;
> }
> private final Object _oldRowKey;
> private final Object _newRowKey;
> }
> /**
> * Listener for RowKeyChangeEvent.
> */
> public interface RowKeyChangeListener
> {
> public void onRowKeyChange(RowKeyChangeEvent event);
> }
> public abstract class CollectionModel extends DataModel
> implements RowKeyIndex
> {
> ...
> /**
> * register the specified listener with the collection model.
> * @param listener The listener to register with the collection model
> */
> public void addRowKeyChangeListener(RowKeyChangeListener listener)
> {
> _rowKeyChangeListeners.add(listener);
> }
> /**
> * unregister the specified listener with the collection model.
> * @param listener The listener to unregister with the collection model
> */
> public void removeRowKeyChangeListener(RowKeyChangeListener listener)
> {
> _rowKeyChangeListeners.remove(listener);
> }
> /**
> * retrieve the registered listeners
> * @return the registered listeners
> */
> public void Set<RowKeyChangeListener> getRowKeyChangeListeners()
> {
> return Collections.unmodifiableSet(_rowKeyChangeListeners);
> }
> ...
> private Set<RowKeyChangeListener> _rowKeyChangeListeners = new
> HashSet<RowKeyChangeListener>();
> }
> Notes regarding the proposal:
> (1) For better performance, if a module holds references to row key, but
> knows that the row key will not change, e.g. read only table, the module
> should not register itself as listener to collection model.
> (2) If a module has difference lifecycle than the collection model, the
> module needs to re-register with collection model as necessarily.
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