MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manual do Utilizador descarregar pdf (Página 102)

102 Data Providers

The following information briefly describes major migration issues:

■ Because the DataProvider interface has been replaced by methods of the collection classes,

controls that have dataProvider properties do not include any of the DataProvider

interface methods, such as getItemAt(). Instead, you manipulate the control contents by

manipulating the object, normally a collection, that acts as the data source. You can use

the methods on the

dataProvider property or on the collection object directly.

For example, you can no longer use the following line:

myList.getItemAt(index).

Instead, use the following line:

myList.dataProvider.getItemAt(index)

In this case, the dataProvider property must specify a collection object that represents the

data.

■ Do not use raw Arrays or Objects in your dataProvider property if the data provider's

values change. The control that displays the data will not get updated when the

underlying data changes. Instead, convert your provider to an ArrayCollection class, as in

the following example:

<?xml version="1.0"?>

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" >

<mx:Script>

import mx.collections.*;

public var myArray:Array = ["MA", "ME", "MI", "MN","MO", "MS",

"MT"];

public var myICV:ICollectionView = new ArrayCollection(myArray);

</mx:Script>

<mx:ComboBox id="myCB0" dataProvider="{myICV}" />

</mx:Application>

■ If you use the DataProvider class directly in an existing application, replace it with the

ArrayCollection or XMLListCollection class. These classes are not one-for-one equivalents

to the old DataProvider class. They do not include the editField, getEditingData,

getItemID, replaceItemAt, sortItems and sortItemsBy methods. If you use any of these

methods, you must different techniques. For sorting, use the Sort class and the sort

property of the ICollectionView interface.

■ The Flex 1.5 Array class implemented the DataProvider interface methods, such as

replaceItemAt() and sortItems(). In Flex 2, there is no separate Flex Array class, only the

Flash Array class, which does not implement such methods. If you used the Array class

and its DataProvider methods, convert the Array to an ArrayCollection and use IList and

ICollectionView interface methods.

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MACROMEDIA FLEX 2-MIGRATING APPLICATIONS TO FLEX 2 Manual do Utilizador Página 102