| Package | mx.collections |
| Class | public class AsyncListView |
| Inheritance | AsyncListView  OnDemandEventDispatcher Object |
| Implements | IList |
| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
getItemAt(), removeItemAt(),
and toArray() methods.
The getItemAt() method handles ItemPendingErrors by returning a provisional
"pending" item until the underlying request succeeds or fails. The provisional
item is produced by calling the function specified by the createPendingItemFunction
property. . If the request
succeeds, the actual item replaces the provisional one.
If it fails, the provisional item is replaced with the item returned by calling
the function specified by the createFailedItemFunction property.
This class delegates the IList methods and properties to its list.
If a list isn't specified, methods that mutate the collection are no-ops,
and methods that query the collection return an empty value, such as null or zero
as appropriate.
This class is intended to be used with Spark components based on DataGroup, such as List and ComboBox. The Spark classes do not provide intrinsic support for ItemPendingError handling.
AsyncListView does not support re-insertion of pending or failed items. Once a failed or pending item is removed, its connection to a pending request for data is lost. Using drag and drop to move a pending item in an ASyncListView, or sorting an ASyncListView that contains pending or failed items, is not supported because these operations remove and then re-insert list items.
MXML Syntax
Show MXML Syntax
Hide MXML SyntaxThe <mx:AsyncListView> tag inherits all the attributes of its
superclass, and adds the following attributes:
<mx:AsyncListView
Properties
createFailedItemFunction="null"
createPendingItemFunction="null"
list="null"
/>
| Property | Defined By | ||
|---|---|---|---|
 | constructor : Object
A reference to the class object or constructor function for a given object instance. | Object | |
| createFailedItemFunction : Function
A callback function used to create a substitute item when
a request which had caused an ItemPendingError to be thrown,
subsequently fails. | AsyncListView | ||
| createPendingItemFunction : Function
A callback function used to create a provisional item when
the initial request causes an ItemPendingError to be thrown. | AsyncListView | ||
| length : int [read-only]
The number of items in this collection. | AsyncListView | ||
| list : IList
The IList object that this collection wraps. | AsyncListView | ||
| Method | Defined By | ||
|---|---|---|---|
AsyncListView(list:IList = null)
Constructor. | AsyncListView | ||
| addEventListener(type:String, listener:Function, useCapture:Boolean = false, priority:int = 0, useWeakReference:Boolean = false):void
Registers an event listener object with an EventDispatcher object so that the listener
receives notification of an event. | OnDemandEventDispatcher | |
Adds the specified item to the end of the list. | AsyncListView | ||
Adds the item at the specified index. | AsyncListView | ||
|
Dispatches an event into the event flow. | OnDemandEventDispatcher | |
Returns the value of list.getItemAt(index). | AsyncListView | ||
Returns the index of the item if it is in the list such that
getItemAt(index) == item. | AsyncListView | ||
|
Checks whether the EventDispatcher object has any listeners registered for a specific type
of event. | OnDemandEventDispatcher | |
|
Indicates whether an object has a specified property defined. | Object | |
|
Indicates whether an instance of the Object class is in the prototype chain of the object specified
as the parameter. | Object | |
itemUpdated(item:Object, property:Object = null, oldValue:Object = null, newValue:Object = null):void
Notifies the view that an item has been updated. | AsyncListView | ||
|
Indicates whether the specified property exists and is enumerable. | Object | |
Removes all items from the list. | AsyncListView | ||
|
Removes a listener from the EventDispatcher object. | OnDemandEventDispatcher | |
Removes the actual or pending item at the specified index and returns it. | AsyncListView | ||
Places the item at the specified index. | AsyncListView | ||
|
Sets the availability of a dynamic property for loop operations. | Object | |
Returns an array with the same elements as this AsyncListView. | AsyncListView | ||
|
Returns the string representation of this object, formatted according to locale-specific conventions. | Object | |
Returns a string that contains the list's length and the number of pending item requests. | AsyncListView | ||
|
Returns the primitive value of the specified object. | Object | |
|
Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type. | OnDemandEventDispatcher | |
| Event | Summary | Defined By | ||
|---|---|---|---|---|
| Dispatched when the list's length has changed or when a list element is replaced. | AsyncListView | |||
createFailedItemFunction | property |
createFailedItemFunction:Function| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
A callback function used to create a substitute item when
a request which had caused an ItemPendingError to be thrown,
subsequently fails. The existing item, typically a pending item created
by the callback function specified by the createPendingItemFunction() property,
is replaced with the failed item.
The value of this property must be a function with two parameters: the index
of the requested item, and the failure "info" object, which is
passed along from the IResponder fault() method.
In most cases you can ignore the second parameter.
Shown below is an example implementation of the callback function:
function createFailedItem(index:int, info:Object):Object
{
return "[" + index + "request failed]";
}
Setting this property does not affect failed items that were already created. Setting this property to null prevents failed items from being created.
The default value is A function that unconditionally returns null..
Implementation
public function get createFailedItemFunction():Function public function set createFailedItemFunction(value:Function):voidRelated API Elements
createPendingItemFunction | property |
createPendingItemFunction:Function| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
A callback function used to create a provisional item when
the initial request causes an ItemPendingError to be thrown.
If the request eventually succeeds, the provisional item is automatically
replaced by the actual item. If the request fails, then the item is replaced
with one created with the callback function specified by the
createFailedItemFunction property.
The value of this property must be a function with two parameters: the index of the requested data provider item, and the ItemPendingError itself. In most cases, the second parameter can be ignored. The following example shows an implementation of the callback function:
function createPendingItem(index:int, ipe:ItemPendingError):Object
{
return "[" + index + "request is pending...]";
}
Setting this property does not affect provisional pending items that were already created. Setting this property to null prevents provisional pending items from being created.
The default value is A function that unconditionally returns null..
Implementation
public function get createPendingItemFunction():Function public function set createPendingItemFunction(value:Function):voidRelated API Elements
length | property |
length:int [read-only] | Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
The number of items in this collection. 0 means no items while -1 means the length is unknown.
This property can be used as the source for data binding. When this property is modified, it dispatches the collectionChange event.
Implementation
public function get length():intlist | property |
list:IList| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
The IList object that this collection wraps. That means the object to which all of the IList methods are delegated.
If this property is null, the IList mutation methods, such as setItemAt(),
are no-ops. The IList query methods, such getItemAt(), return null
or zero (-1 for getItemIndex()), as appropriate.
The default value is null.
This property can be used as the source for data binding. When this property is modified, it dispatches the listChanged event.
Implementation
public function get list():IList public function set list(value:IList):voidAsyncListView | () | Constructor |
addItem | () | method |
addItemAt | () | method |
public function addItemAt(item:Object, index:int):void| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Adds the item at the specified index. The index of any item greater than the index of the added item is increased by one. If the the specified index is less than zero or greater than the length of the list, a RangeError is thrown.
Parameters
item:Object — The item to place at the index.
| |
index:int — The index at which to place the item.
|
getItemAt | () | method |
public function getItemAt(index:int, prefetch:int = 0):Object| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Returns the value of list.getItemAt(index).
This method catches ItemPendingErrors (IPEs) generated as a consequence of
calling getItemAt(). If an IPE is thrown, an IResponder is added to
the IPE and a provisional "pending" item, created with the
createPendingItemFunction is returned. If the underlying request
eventually succeeds, the pending item is replaced with the real item. If it fails,
the pending item is replaced with a value produced by calling
createFailedItemFunction.
Parameters
index:int — The list index from which to retrieve the item.
| |
prefetch:int (default = 0)int indicating both the direction
and number of items to fetch during the request if the item is not local.
|
Object — The list item at the specified index.
|
Throws
RangeError — if index < 0 or index >= length.
|
Related API Elements
getItemIndex | () | method |
public function getItemIndex(item:Object):int| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Returns the index of the item if it is in the list such that getItemAt(index) == item.
Note: unlike IViewCursor.findxxx() methods,
The getItemIndex() method cannot take a parameter with
only a subset of the fields in the item being serched for;
this method always searches for an item that exactly matches
the input parameter.
Parameters
item:Object — The item to find.
|
int — The index of the item, or -1 if the item is not in the list.
|
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 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Notifies the view that an item has been updated.
This is useful if the contents of the view do not implement
IEventDispatcher and dispatches a
PropertyChangeEvent.
If a property is specified 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) | |
oldValue:Object (default = null) | |
newValue:Object (default = null) |
removeAll | () | method |
public function removeAll():void| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Removes all items from the list.
If any item is not local and an asynchronous operation must be
performed, an ItemPendingError will be thrown.
See the ItemPendingError documentation as well as
the collections documentation for more information
on using the ItemPendingError.
removeItemAt | () | method |
public function removeItemAt(index:int):Object| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Removes the actual or pending item at the specified index and returns it. All items whose index is greater than the specified index have their index reduced by 1.
If there is no actual or pending item at the specified index, for
example because a call to getItemAt(index) hasn't caused the data to be
paged in, then the underlying list may throw an ItemPendingError.
The implementation ignores the ItemPendingError and returns null.
Parameters
index:int — The list index from which to retrieve the item.
|
Object — The item that was removed or null.
|
Throws
RangeError — if index < 0 or index >= length.
|
setItemAt | () | method |
public function setItemAt(item:Object, index:int):Object| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Places the item at the specified index. If an item was already at that index the new item will replace it and it will be returned.
Parameters
item:Object — The new item to be placed at the specified index.
| |
index:int — The index at which to place the item.
|
Object — The item that was replaced, or null if none.
|
toArray | () | method |
public function toArray():Array| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Returns an array with the same elements as this AsyncListView. The array is initialized
by retrieving each item with getItemAt(), so pending items are substituted where actual
values aren't available yet. The array will not be updated when the AsyncListView replaces
the pending items with actual (or failed) values.
Array — an array with the same elements as this AsyncListView.
|
toString | () | method |
public function toString():String| Language Version: | ActionScript 3.0 |
| Product Version: | Flex 4 |
| Runtime Versions: | Flash Player 10, AIR 1.5 |
Returns a string that contains the list's length and the number of pending item requests. It does not trigger pending requests.
ReturnsString — A brief description of the list.
|
collectionChange | Event |
mx.events.CollectionEventproperty CollectionEvent.type =
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 list's length has changed or when a list element is replaced.
The CollectionEvent.COLLECTION_CHANGE constant defines the value of thetype 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 21 2018, 06:34 AM -08:00