[jira] Commented: (TAP5-1407) multizoneupdate should be easier to use - not a chain

["Howard M. Lewis Ship (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TAP5-1407?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12978883#action_12978883 ] 

Howard M. Lewis Ship commented on TAP5-1407:
--------------------------------------------

Actually, I'm thinking the MultiZoneUpdate object could be deprecated, and a service take its place.  MZU is just a bit unwieldy to use, despite some work on it in 5.2 and, in the long run, it doesn't actually prevent some amount of per-thread state from being stored ... in other words, over-engineered.  

> multizoneupdate should be easier to use - not a chain
> -----------------------------------------------------
>
>                 Key: TAP5-1407
>                 URL: https://issues.apache.org/jira/browse/TAP5-1407
>             Project: Tapestry 5
>          Issue Type: Improvement
>          Components: tapestry-core
>    Affects Versions: 5.2.4
>            Reporter: Paul Stanton
>             Fix For: 5.2.4
>
>
> Currently MultiZoneUpdate is a chain of MultiZoneUpdates, ie
> public class MultiZoneUpdate
> {
> ...
>     public MultiZoneUpdate add(String zoneId, Object renderer)
>     {
>         return new MultiZoneUpdate(zoneId, renderer, this);
>     }
> ...
> }
> usage:
> MultiZoneUpdate mzu = new MultiZoneUpdate("zone2", zone1); // ugly!
> mzu = mzu.add("zone2", zone2); // ugly!
> mzu = mzu.add("zone3", zone3); // ugly!
> ...
> return mzu;
> This becomes hard to use when event handlers call common methods which contribute zone updates.
> Also, it is possible to request multiple updates for the one zone which doesn't make much sense.
> In some cases it would be much easier if you could construct a MultiZoneUpdate object without actually contributing a zone update directive. ie:
> MultiZoneUpdate mzu = new MultiZoneUpdate();
> mzu.add("zone2", zone1);
> mzu.add("zone2", zone2);
> mzu.add("zone3", zone3);
> mzu.add("zone3", zone3); // knocks out prev zone3 update
> ...
> return mzu;
> I have created a utility class which helps me work around this issue (and issue #TAP5-1406), however note it relies on the dummy zone hack.:
> import java.util.HashMap;
> import java.util.Map.Entry;
> import org.apache.tapestry5.ComponentResources;
> import org.apache.tapestry5.MarkupWriter;
> import org.apache.tapestry5.ajax.MultiZoneUpdate;
> import org.apache.tapestry5.internal.services.PageRenderQueue;
> import org.apache.tapestry5.json.JSONObject;
> import org.apache.tapestry5.services.PartialMarkupRenderer;
> import org.apache.tapestry5.services.PartialMarkupRendererFilter;
> import org.apache.tapestry5.services.javascript.JavaScriptSupport;
> public class XHRResponseHelper
> {
> 	private HashMap<String, Object> zoneUpdates;
> 	private boolean scriptAdded;
> 	public XHRResponseHelper()
> 	{
> 		this.zoneUpdates = new HashMap<String, Object>();
> 		scriptAdded = false;
> 	}
> 	public void addScriptCall(final String script, PageRenderQueue pageRenderQueue, final JavaScriptSupport javascriptSupport)
> 	{
> 		scriptAdded = true;
> 		pageRenderQueue.addPartialMarkupRendererFilter(new PartialMarkupRendererFilter()
> 		{
> 			public void renderMarkup(MarkupWriter writer, JSONObject reply, PartialMarkupRenderer renderer)
> 			{
> 				javascriptSupport.addScript(script);
> 				renderer.renderMarkup(writer, reply);
> 			}
> 		});
> 	}
> 	public void addZoneUpdate(String zoneId, ComponentResources componentResources)
> 	{
> 		addZoneUpdate(zoneId, componentResources.getEmbeddedComponent(zoneId));
> 	}
> 	public void addZoneUpdate(String zoneId, Object renderer)
> 	{
> 		zoneUpdates.put(zoneId, renderer);
> 	}
> 	public MultiZoneUpdate buildMultiZoneUpdate(ComponentResources componentResources)
> 	{
> 		// work around issue  - https://issues.apache.org/jira/browse/TAP5-1406
> 		if (zoneUpdates.isEmpty() && scriptAdded)
> 			addZoneUpdate("dummyZone", componentResources);
> 		MultiZoneUpdate mzu = null;
> 		for (Entry<String, Object> entry : zoneUpdates.entrySet())
> 		{
> 			if (mzu == null)
> 				mzu = new MultiZoneUpdate(entry.getKey(), entry.getValue());
> 			else
> 				mzu.add(entry.getKey(), entry.getValue());
> 		}
> 		return mzu; // null if zoneUpdates is empty
> 	}
> }
> usage:
> XHRResponseHelper response = new XHRResponseHelper();
> response.addZoneUpdate("myZone", componentResources);
> response.addZoneUpdate("myZone2", block);
> response.addScriptCall("alert('script');", pageRenderQueue, javascriptSupport);
> return response.buildMultiZoneUpdate(componentResources);
> hope that helps.

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