Sort collection and sort remains in place when adding to collection?

问题

When I get a collection back from the service tier, I create an ArrayCollection and apply a sort. When I add an item to the collection later on, the sort is still in place? It seems to be the case. I thought I was only sorting it once, not applying a sort that will stick???

Here is the method for adding an item:

private function onAddNewClick():void
        {
            var fileTemplate:FileTemplateDetailDTO = new FileTemplateDetailDTO();   
            fileTemplate.fileTemplateId = 0;
            fileTemplate.fileTmpltDtlId = 0;
            fileTemplate.createdBy = appModel.userName;

            newFieldsDp.addItem( fileTemplate );

            this.fieldsGridEmpty.rowCount = newFieldsDp.length + 1;
            totalCount = newFieldsDp.length;
            this.fieldsGridEmpty.scrollToIndex( totalCount );
        }

And here is what I'm trying now for when the data comes back from the service:

for each( var dto:FileTemplateCompositeDTO in coll ){
            dto.templateHistory = createHistoryColl( dto.details );
            var sortedArray:ArrayCollection = sortDetails( dto.details );
            sortedArray.sort = null;
            var freshArray:Array = sortedArray.toArray();
            dto.details.source = freshArray;
            model.fileTemplateComposites.addItem( FileTemplateCompositeDTO( dto ) );
        }

回答1:

Easiest way to do a one time sort:

var array:Array = yourArrayCollection.toArray():
array.sortOn("SomePropertyAvailableInEachItem", Array.DESCENDING | Array.NUMERIC);
yourArrayCollection.refresh();

Since you're not sorting the underlying Array, and not the collection.

回答2:

No. You should call myCollection.refresh() every time it is changed. But you can listen for collectionChange event and call refresh from there:

    private function collectionChangeHandler(event:CollectionEvent):void
    {
        if (event.kind == CollectionEventKind.ADD || event.kind == CollectionEventKind.REMOVE ||
            event.kind == CollectionEventKind.REPLACE || event.kind == CollectionEventKind.MOVE || event.kind == CollectionEventKind.UPDATE)
        {
            ArrayCollection(event.currentTarget).refresh();
        }
    }

回答3:

The sort of an ArrayCollection will remain linked to it. You can try to set the sort attribute to null after the initial sort and refresh, but I'm not 100% sure that a following refresh() will keep the elements order (although it should).

Another approach: after applying the initial sort to your collection, you can call its toArray() method to obtain a (sorted) array, then just create a new ArrayCollection passing that array as its source in the constructor. Note that ArrayCollection is really just a wrapper on array, so the toArray() and the construction of a new ArrayCollection for an existing array should not be heavy operations.

回答4:

A Sort on an ArrayCollection is an object itself. When you assign the Sort object to the sort property on the ArrayCollection, it remains assigned until you remove it manually. To remove it, just set the sort property on your ArrayCollection to null after you call refresh().

myArrayCollection.sort = mySort;
myArrayCollection.refresh();
myArrayCollection.sort = null;

Now any time you call refresh() on the ArrayCollection, the sort is no longer in place.

来源：https://stackoverflow.com/questions/6536605/sort-collection-and-sort-remains-in-place-when-adding-to-collection