Update Array Via ICollectionView
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<!-- dpcontrols\UpdateArrayViaICollectionView.mxml -->
<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" initialize="initData();">
<s:layout>
<s:VerticalLayout />
</s:layout>
<fx:Script>
import mx.collections.*;
// The data provider is an array of Strings.
public var myArray:Array = ["AZ", "MA", "MZ", "MN", "MO", "MS"];
// Declare an ArrayCollection that represents the Array.
// The variable must be bindable so the ComboBox can update properly.
[Bindable]
public var myAC:ArrayCollection;
//Boolean flag to ensure the update routine hasn't been run before.
public var runBefore:Boolean=false;
//Initialize the ArrayCollection the application initializes.
public function initData():void {
myAC = new ArrayCollection(myArray);
}
// The function to change the collection.
public function changeCollection():void {
//Running this twice without resetting causes an error.
if (! runBefore) {
runBefore=true;
// Get an IViewCursor object for accessing the collection data.
var myCursor:IViewCursor=myAC.createCursor();
// Get the original collection length.
var oldLength:int=myAC.length;
// The cursor is initially at the first item; delete it.
var removedItem:String=String(myCursor.remove());
// Add ME as the second item.
// The cursor is at the (new) first item;
// move it to the second item.
myCursor.moveNext();
// Insert ME before the second item.
myCursor.insert("ME");
// Add MT at the end of the collection.
//Use the LAST bookmark property to go to the end of the view.
// Add an offset of 1 to position the cursor after the last item.
myCursor.seek(CursorBookmark.LAST, 1);
myCursor.insert("MT");
// Change MZ to MI.
// The findFirst() method requires a sorted view.
var sort:Sort = new Sort();
myAC.sort=sort;
// Refresh the collection view to apply the sort.
myAC.refresh();
// Make sure there is a MZ item, and no MI in the array.
if (myCursor.findFirst("MZ") && !myCursor.findFirst("MI")) {
// The IViewCursor does not have a replace operation.
// First, remove "MZ".
myCursor.remove();
// Because the view is now sorted, the insert puts this item
// in the right place in the sorted view, but at the end of
// the underlying Array data provider.
myCursor.insert("MI");
}
// Get the updated collection length.
var newLength:int=myAC.length;
// Set a bookmark at the item with the value ME,
myCursor.findFirst("ME");
var MEMark:CursorBookmark=myCursor.bookmark;
// Move the cursor to the last item in the Array.
myCursor.seek(CursorBookmark.LAST);
// Get the last item in the collection.
var lastItem:String=String(myCursor.current);
// Return the cursor to the bookmark position.
myCursor.seek(MEMark);
// Get the item at the cursor location.
var MEItem:String=String(myCursor.current);
// Display the information in the TextArea control.
ta1.text="Start Length: " + oldLength + ". End Length: " + newLength;
ta1.text+=".\nRemoved " + removedItem;
ta1.text+=".\nLast Item is " + lastItem;
ta1.text+=".\nItem at MEMark is " + MEItem;
// Show that the base Array has been changed.
// Notice that the Array is NOT in sorted order.
ta1.text+="\nThe base Array is: " + myArray.join();
} // End runBefore condition
}
// Filter function used in the sortICV method to limit the range.
public function MEMOFilter(item:Object):Boolean {
return item >= "ME" && item <= "MO";
}
// Sort the collection view in descending order,
// and limit the items to the range ME - MO.
public function sortICV():void {
var sort:Sort = new Sort();
sort.fields=[new SortField(null, false, true)];
myAC.filterFunction=MEMOFilter;
myAC.sort=sort;
// Refresh the ArrayCollection to apply the sort and filter
// function.
myAC.refresh();
//Call the ComboBox selectedIndex() method to replace the "MA"
//in the display with the first item in the sorted view.
myCB.selectedIndex=0;
ta1.text="Sorted";
}
//Reset the Array and update the display to run the example again.
public function resetView():void {
myArray = ["AZ", "MA", "MZ", "MN", "MO", "MS"];
myAC = new ArrayCollection(myArray);
ta1.text="Reset";
runBefore=false;
}
</fx:Script>
<s:ComboBox id="myCB" dataProvider="{myAC}" />
<s:TextArea id="ta1" height="75" width="300" />
<s:HGroup>
<s:Button label="Update View" click="changeCollection();" />
<s:Button label="Sort View" click="sortICV();" />
<s:Button label="Reset View" click="resetView();" />
</s:HGroup>
</s:Application>
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