RE: [flexcoders] ListCollectionView dispatches too many CollectionEvents after enableAutoUpdate

[Alex Harui]

I suppose we should have called it "queueUpUpdatesUntilLater" and
"sendAllQueuedUpUpdatees".

 

IMHO, there's an upper limit where, instead of changing piecemeal, you
should just set a new source, which should just send one big RESET
event.

 

________________________________

From: flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] On
Behalf Of t0ml33
Sent: Wednesday, November 21, 2007 11:58 AM
To: flexcoders@yahoogroups.com
Subject: [flexcoders] ListCollectionView dispatches too many
CollectionEvents after enableAutoUpdate

 

I am making some updates to an ArrayCollection. Since it's the 
dataSource for a DataGrid, and I want the binding to update as few 
times as possible, I am using ArrayCollection.disableAutoUpdate(), 
making the changes, and then calling enableAutoUpdate() thinking that 
this will cause the binding to refresh only once for all the 
changes. This would be the case if the ArrayCollection were 
dispatching events of kind CollectionEventKind.UPDATE. Alas, since I 
am replacing the items in the ArrayCollection and not merely updating 
them, it is CollectionEventKind.REPLACE. As you can see from 
handlePendingUpdates() in ListCollectionView, it only gangs the 
updates into a single refresh if the event.kind == 
CollectionEventKind.UPDATE. All other CollectionEvents are fired 
sequentially, which would seem to defeat the purpose of 
disableAutoUpdate. Could someone clue me in on why this should be 
the case? I'm tempted to monkey-patch around it, and submit a bug. 
See the code below.

Thanks,

-tom

private function handlePendingUpdates():void
{
if (pendingUpdates)
{
var pu:Array = pendingUpdates;
pendingUpdates = null;

// Could further optimize to consolidate various events
// and make a decision if there are too many updates
// and we should just refresh.
var singleUpdateEvent:CollectionEvent;
for (var i:int = 0; i < pu.length; i++)
{
var event:CollectionEvent = pu[i];

// ****** Here's the offending code
if (event.kind == CollectionEventKind.UPDATE)
{
if (!singleUpdateEvent)
{
singleUpdateEvent = event;
}
else
{
for (var j:int = 0; j < event.items.length; 
j++)
{
singleUpdateEvent.items.push(event.items
[j]);
}
}
}
else
{
listChangeHandler(event);
}
}

if (singleUpdateEvent)
{
listChangeHandler(singleUpdateEvent);
}
}
}