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ICollectionView

Package | mx.collections
Interface | public interface ICollectionView extends flash.events.IEventDispatcher
Implementors | ListCollectionView, VectorCollection

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

An `ICollectionView` is a view onto a collection of data. The view can be modified to show the data sorted according to various criteria or reduced by filters without modifying the underlying data. An IViewCursor provides to access items within a collection. You can modify the collection by using the IViewCursor interface `insert()` and `remove()` methods.

An `ICollectionView` may be a view onto data that has been retrieved from a remote location. When Implementing this interface for data that may be remote it is important to handle the case where data may not yet be available, which is indicated by the `ItemPendingError`.

The `IList` interface is an alternative to the `ICollectionView` interface.

See also

mx.collections.IViewCursor
mx.collections.errors.ItemPendingError
mx.collections.IList

Public Properties

| Property | Defined By
--- | --- | ---
|  | filterFunction : Function A function that the view will use to eliminate items that do not match the function's criteria. | ICollectionView
|  | length : int [read-only] The number of items in this view. | ICollectionView
|  | sort : ISort The ISort that will be applied to the ICollectionView. | ICollectionView

Public Methods

| Method | Defined By
--- | --- | ---
|  | contains(item:Object):Boolean Returns whether the view contains the specified object. | ICollectionView
|  | createCursor():IViewCursor Creates a new IViewCursor that works with this view. | ICollectionView
|  | disableAutoUpdate():void Prevents changes to the collection itself and items within the collection from being dispatched by the view. | ICollectionView
|  | enableAutoUpdate():void Enables auto-updating. | ICollectionView
|  | itemUpdated(item:Object, property:Object = null, oldValue:Object = null, newValue:Object = null):void Notifies the view that an item has been updated. | ICollectionView
|  | refresh():Boolean Applies the sort and filter to the view. | ICollectionView

Events

| Event | Summary | Defined By
--- | --- | --- | ---
|  | collectionChange | Dispatched when the ICollectionView has been updated in some way. | ICollectionView

Property Detail

filterFunction | property

`filterFunction:Function`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

A function that the view will use to eliminate items that do not match the function's criteria. A filterFunction is expected to have the following signature:

    f(item:Object):Boolean

where the return value is `true` if the specified item should remain in the view.

If a filter is unsupported, Flex throws an error when accessing this property. You must call `refresh()` after setting the `filterFunction` property for the view to update.

Note: The Flex implementations of ICollectionView retrieve all items from a remote location before executing the filter function. If you use paging, apply the filter to the remote collection before you retrieve the data.

Implementation
`public function get filterFunction():Function`
`public function set filterFunction(value:Function):void`

See also

refresh()

length | property |

`length:int` [read-only]

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

The number of items in this view. 0 means no items, while -1 means that the length is unknown.

Implementation
`public function get length():int`

sort | property |

`sort:ISort`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

The ISort that will be applied to the ICollectionView. Setting the sort does not automatically refresh the view, so you must call the `refresh()` method after setting this property. If sort is unsupported an error will be thrown when accessing this property.

Note: The Flex implementations of ICollectionView retrieve all items from a remote location before executing a sort. If you use paging with a sorted list, apply the sort to the remote collection before you retrieve the data.

Implementation
`public function get sort():ISort`
`public function set sort(value:ISort):void`

See also

refresh()
Method Detail

contains | () | method

`public function contains(item:Object):Boolean`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

Returns whether the view contains the specified object. Unlike the `IViewCursor.findxxx` methods, this search is succesful only if it finds an item that exactly matches the parameter. If the view has a filter applied to it this method may return `false` even if the underlying collection does contain the item.

Parameters

| `item:Object` — The object to look for.

Returns

| `Boolean` — true if the ICollectionView, after applying any filter, contains the item; false otherwise.

createCursor | () | method |

`public function createCursor():IViewCursor`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

Creates a new IViewCursor that works with this view.

Returns

| `IViewCursor` — A new IViewCursor implementation.

disableAutoUpdate | () | method |

`public function disableAutoUpdate():void`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

Prevents changes to the collection itself and items within the collection from being dispatched by the view. Also prevents the view from updating the positions of items if the positions change in the collection. The changes will be queued and dispatched appropriately after `enableAutoUpdate` is called. If more events than updates to a single item occur, the view may end up resetting. The `disableAutoUpdate` method acts cumulatively; the same number of calls to `enableAutoUpdate` are required for the view to dispatch events and refresh. Note that `disableAutoUpdate` only affects the individual view; edits may be detected on an individual basis by other views.

enableAutoUpdate | () | method |

`public function enableAutoUpdate():void`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

Enables auto-updating. See `disableAutoUpdate` for more information.

See also

disableAutoUpdate()

itemUpdated | () | method |

`public function itemUpdated(item:Object, property:Object = null, oldValue:Object = null, newValue:Object = null):void`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

Notifies the view that an item has been updated. This method is useful if the contents of the view do not implement `IPropertyChangeNotifier`. If the call to this method includes a `property` parameter, the view may be able to optimize its notification mechanism. Otherwise it may choose to simply refresh the whole view.

Parameters

| `item:Object` — The item within the view that was updated.
| `property:Object` (default = `null`)`` — The name of the property that was updated.
| `oldValue:Object` (default = `null`)`` — The old value of that property. (If property was null, this can be the old value of the item.).
| `newValue:Object` (default = `null`)`` — The new value of that property. (If property was null, there's no need to specify this as the item is assumed to be the new value.)

See also

mx.events.CollectionEvent
mx.core.IPropertyChangeNotifier
mx.events.PropertyChangeEvent

refresh | () | method |

`public function refresh():Boolean`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

Applies the sort and filter to the view. The ICollectionView does not detect changes to a sort or filter automatically, so you must call the `refresh()` method to update the view after setting the `sort` or `filterFunction` property. If your ICollectionView implementation also implements the IMXMLObject interface, you should to call the `refresh()` method from your `initialized()` method.

Returns `true` if the refresh was successful and `false` if the sort is not yet complete (e.g., items are still pending). A client of the view should wait for a CollectionEvent event with the `CollectionEventKind.REFRESH` `kind` property to ensure that the `refresh()` operation is complete.

Returns

| `Boolean` — `true` if the refresh() was complete, `false` if the refresh() is incomplete.

Event Detail

collectionChange | Event

Event Object Type: `mx.events.CollectionEvent`
CollectionEvent.type property = `mx.events.CollectionEvent.COLLECTION_CHANGE`

Language Version : | ActionScript 3.0

Product Version : | Flex 3

Runtime Versions : | Flash Player 9, AIR 1.1

Dispatched when the ICollectionView has been updated in some way.

The CollectionEvent.COLLECTION_CHANGE constant defines the value of the `type` property of the event object for an event that is dispatched when a collection has changed.

The properties of the event object have the following values. Not all properties are meaningful for all kinds of events. See the detailed property descriptions for more information.

Property | Value
--- | ---
`bubbles` | false
`cancelable` | false
`currentTarget` | The Object that defines the event listener that handles the event. For example, if you use `myButton.addEventListener()` to register an event listener, myButton is the value of the `currentTarget`.
`items` | An Array of objects with information about the items affected by the event. The contents of this field depend on the event kind; for details see the `items` property
`kind` | The kind of event. The valid values are defined in the CollectionEventKind class as constants.
`location` | Location within the target collection of the item(s) specified in the `items` property.
`oldLocation` | the previous location in the collection of the item specified in the `items` property.
`target` | The Object that dispatched the event; it is not always the Object listening for the event. Use the `currentTarget` property to always access the Object listening for the event.
`type` | CollectionEvent.COLLECTION_CHANGE

Wed Nov 15 2017, 09:50 AM +01:00