mx.data.MessageBatch - Adobe® Flex® 4 Language Reference (Flex 4)

Package	mx.data
Class	public class MessageBatch
Inheritance	MessageBatch EventDispatcher Object
Implements	IExternalizable

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

Represents a group of changes: creates, updates, deletes, and update collection messages. There is always at least one open batch accessible via the DataStore.currentBatch property. Changes you make such as property changes detected automatically through data binding, createItem, updateItem, or deleteItem operations will be stored in this batch. The current list of uncommitted batches is stored in the uncommittedBatches property. You call createBatch create a new batch which is added to the end of the list. This batch is automatically made the currentBatch. You can commit or revert the set of a changes a batch at a time - in both cases, the batch is automatically removed from the uncommittedBatches list.

When there are dependencies between changes, you should commit and revert changes in order - i.e. commit the oldest batch in the list (uncommittedBatches[0]) and revert the most recent batch - uncommittedBatches[uncommittedBatches.length - 1].

The commitRequired property is set to true when there are any changes in the batch (i.e. items.length > 0). The items property stores the set of DataMessages in this batch.

You can store custom information in a MessageBatch via the properties property. Batches are saved/restored each time you use the saveCache method or automatically when autoSaveCache is true when using the offline feature.

Each batch also has a DataMessage associated with it in the batchMessage property. If you need to communicate information with the server (and you are sending the batch message to the server) you can store info in the headers of this message.

Public Properties

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	Property		Defined By
		batchMessage : DataMessage This is the data message used to represent the batch being sent to the server If you need to pass additional per-transaction information you might use the headers of this message to communicate with your server code (assuming it actually sends the message instead of converting it on the client)	MessageBatch
		commitRequired : Boolean [read-only] True if any changes are in this batch.	MessageBatch
		constructor : Object A reference to the class object or constructor function for a given object instance.	Object
		properties : Object = null An optional set of user defined properties you can set for this batch	MessageBatch
		prototype : Object [static] A reference to the prototype object of a class or function object.	Object

Public Methods

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	Method		Defined By
		MessageBatch() Constructor.	MessageBatch
		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.	EventDispatcher
		commit(itemsOrCollections:Array = null, cascadeCommit:Boolean = false):mx.rpc:AsyncToken Commits the changes in the batch.	MessageBatch
		dispatchEvent(event:Event):Boolean Dispatches an event into the event flow.	EventDispatcher
		getMessage(messageId:String):DataMessage Returns the message with the given id.	MessageBatch
		hasEventListener(type:String):Boolean Checks whether the EventDispatcher object has any listeners registered for a specific type of event.	EventDispatcher
		hasOwnProperty(name:String):Boolean Indicates whether an object has a specified property defined.	Object
		isPrototypeOf(theClass:Object):Boolean Indicates whether an instance of the Object class is in the prototype chain of the object specified as the parameter.	Object
		propertyIsEnumerable(name:String):Boolean Indicates whether the specified property exists and is enumerable.	Object
		readExternal(input:IDataInput):void This method de-serializes the message batch.	MessageBatch
		removeEventListener(type:String, listener:Function, useCapture:Boolean = false):void Removes a listener from the EventDispatcher object.	EventDispatcher
		removeMessage(msg:DataMessage):void Removes the specified message from this batch.	MessageBatch
		revertChanges(item:IManaged = null):Boolean Reverts the changes for this batch - either all changes if no item is supplied - or just the changes for the specified item if it is supplied.	MessageBatch
		revertChangesForCollection(collection:ListCollectionView):Boolean Reverts the changes for all items in the specified managed collection.	MessageBatch
		setPropertyIsEnumerable(name:String, isEnum:Boolean = true):void Sets the availability of a dynamic property for loop operations.	Object
		toLocaleString():String Returns the string representation of this object, formatted according to locale-specific conventions.	Object
		toString():String [override] Returns a String representation of this object.	MessageBatch
		valueOf():Object Returns the primitive value of the specified object.	Object
		willTrigger(type:String):Boolean Checks whether an event listener is registered with this EventDispatcher object or any of its ancestors for the specified event type.	EventDispatcher
		writeExternal(output:IDataOutput):void This method serializes the batch with the following stucture: numberOfElements:int - this is the total number of elements serialized [repeated element (once for every message in the batch)] destination:String - the destination of the associated DataService uid:String - the UID of the associated item message:DataMessage - the message for the associated change Because the message currently contains a copy of the item we don't have to serialize the message in a special way.	MessageBatch

Events

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	Event		Summary	Defined By
		activate	[broadcast event] Dispatched when the Flash Player or AIR application gains operating system focus and becomes active.	EventDispatcher
		deactivate	[broadcast event] Dispatched when the Flash Player or AIR application operating loses system focus and is becoming inactive.	EventDispatcher

Public Constants

	Constant		Defined By
		items : ArrayCollection This stores the list of MessageCacheItem instances which represent the changes in the batch.	MessageBatch

Property Detail

batchMessage

property

public var batchMessage:DataMessage

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

This is the data message used to represent the batch being sent to the server If you need to pass additional per-transaction information you might use the headers of this message to communicate with your server code (assuming it actually sends the message instead of converting it on the client)

commitRequired

property

commitRequired:Boolean [read-only]

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

True if any changes are in this batch. A bindable property.

This property can be used as the source for data binding. When this property is modified, it dispatches the propertyChange event.

Implementation
public function get commitRequired():Boolean

properties

property

public var properties:Object = null

An optional set of user defined properties you can set for this batch

Constructor Detail

MessageBatch

()

Constructor

public function MessageBatch()

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

Constructor.

Method Detail

commit

()

method

public function commit(itemsOrCollections:Array = null, cascadeCommit:Boolean = false):mx.rpc:AsyncToken

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

Commits the changes in the batch. Typically called with no arguments.

Parameters

	`itemsOrCollections:Array` (default = `null`) — If you want to commit only some of the changes in the batch, you can commit changes for an item at a time or a collection of items at a time by setting the `itemsOrCollections` parameter.

	`cascadeCommit:Boolean` (default = `false`) — Set to `true` to ensures that changes to associated items are also included in the commit.

Returns

mx.rpc:AsyncToken — AsyncToken reference to the token that will identify this operation in a result or fault event dispatched from this service.

getMessage

()

method

public function getMessage(messageId:String):DataMessage

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

Returns the message with the given id. Returns null of no message with the given id exists in this batch.

Parameters

messageId:String — id of desired message.

Returns

DataMessage — the message with the given id. Returns null of no message with the given id exists in this batch.

readExternal

()

method

public function readExternal(input:IDataInput):void

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

This method de-serializes the message batch. It expects the input byte stream to have the following structure: numberOfElements:int - this is the total number of elements serialized [repeated element (once for every message in the batch)] t] destination:String - the destination of the associated DataService uid:String - the UID of the associated item message:DataMessage - the message for the associated change

Parameters

input:IDataInput — input stream

removeMessage

()

method

public function removeMessage(msg:DataMessage):void

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

Removes the specified message from this batch.

Parameters

msg:DataMessage — message to be removed.

revertChanges

()

method

public function revertChanges(item:IManaged = null):Boolean

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

Reverts the changes for this batch - either all changes if no item is supplied - or just the changes for the specified item if it is supplied. You should typically only revert changes in the most recent batch as the system does not resolve or fix dependencies if you revert an older change which was depended upon by a later change.

Parameters

item:IManaged (default = null) — The item to revert.

Returns

Boolean — true if the revert completed successfully.

revertChangesForCollection

()

method

public function revertChangesForCollection(collection:ListCollectionView):Boolean

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

Reverts the changes for all items in the specified managed collection.

Parameters

collection:ListCollectionView — The collection to revert.

Returns

Boolean — true if the revert completed successfully.

toString

()

method

override public function toString():String

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

Returns a String representation of this object.

Returns

String — A String representation of this object.

writeExternal

()

method

public function writeExternal(output:IDataOutput):void

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

This method serializes the batch with the following stucture: numberOfElements:int - this is the total number of elements serialized [repeated element (once for every message in the batch)] destination:String - the destination of the associated DataService uid:String - the UID of the associated item message:DataMessage - the message for the associated change Because the message currently contains a copy of the item we don't have to serialize the message in a special way.

Parameters

output:IDataOutput — object to write serialized bytes to.

Constant Detail

items

Constant

public const items:ArrayCollection

Language Version:

ActionScript 3.0

Product Version:

LiveCycle Data Services 3

Runtime Versions:

Flash Player 9, AIR 1.1

This stores the list of MessageCacheItem instances which represent the changes in the batch. It is bindable so you can listen for change events on this collection to be notified of new changes.