Question

<s:Application xmlns:fx="http://ns.adobe.com/mxml/2009" 
           xmlns:s="library://ns.adobe.com/flex/spark" 
           xmlns:mx="library://ns.adobe.com/flex/mx" minWidth="955" minHeight="600"
           creationComplete="init()">

This is my header, and this is the function that is being called by creationComplete:

protected function init():void
        {
            var mySort:Sort = new Sort();
            mySort.fields = [new SortField('title')];
            acCart.sort = mySort;
            acCart.refresh();
        }

Now, I’m adding some objects from one arraycollection (shop) to another (cart) basically (shown in a datagrid). The cart-datagrid is being modified everytime I press the button “add to cart”.

I thought that the creationcomplete-statement was only executed once, but now I’m in doubt, because it’s the only function that contains the refresh() and if I delete it, my cart isn’t updatet anymore. Can somebody provide me with some more information about the creationcomplete statement? A search on the internet and in my textbook hasn’t learned me what it exactly does.

Answer 1

Upon creation complete, your acCart ArrayCollection is sorted; however, components bound to that ArrayCollection should update upon adding objects to an ArrayCollection.

ArrayCollection is a very heavy collection, dispatching events upon collection change.

Once bound to a DataGrid, alterations to the collection will be reflected within the DataGrid.

http://blog.flexdevelopers.com/2009/03/flex-basics-arraycollection.html

…an ArrayCollection is a “wrapper class that exposes an Array as a
collection that can be accessed and manipulated using the methods and
properties of the ICollectionView or IList interfaces”.
Two members of the ArrayCollection class are integral to the ArrayCollection’s ability to support data binding – The
collectionChange event and addEventListener method. To participate in
data binding, an object must be able to:

1. dispatch an event when something changes
2. allow other objects to listen and respond to event

Creation Complete:

Dispatched when the component, and all its child components, and all
their children, and so on, have been created, laid out, and are
visible.

Flex dispatches the creationComplete event for a container when those
children that are initially required are fully processed and drawn on
the screen, including all required children of the children, and so
on. Create a listener for the creationComplete event, for example, if
you must have the children’s dimensions and positions in your event
handler. Do not use the creationComplete event for actions that set
layout properties, as doing so results in excess processing time.