Class Ext.tree.TreeLoader

Package:	Ext.tree
Class:	TreeLoader
Extends:	Observable
Defined In:	TreeLoader.js

A TreeLoader provides for lazy loading of an Ext.tree.TreeNode's child nodes from a specified URL. The response must be a javascript Array definition who's elements are node definition objects. eg:

[{ 'id': 1, 'text': 'A folder Node', 'leaf': false },
    { 'id': 2, 'text': 'A leaf Node', 'leaf': true }]

A server request is sent, and child nodes are loaded only when a node is expanded. The loading node's id is passed to the server under the parameter name "node" to enable the server to produce the correct child nodes.

To pass extra parameters, an event handler may be attached to the "beforeload" event, and the parameters specified in the TreeLoader's baseParams property:


    myTreeLoader.on("beforeload", function(treeLoader, node) {
        this.baseParams.category = node.attributes.category;
    }, this);

< This would pass an HTTP parameter called "category" to the server containing the value of the Node's "category" attribute.

Properties - Methods - Events - Config Options

Public Properties

This class has no public properties.

Public Methods

Method		Defined By
	TreeLoader(`Object config`)	TreeLoader
	Creates a new Treeloader.	TreeLoader
	addEvents(`Object object`) : void	Observable
	Used to define events on this Observable	Observable
	addListener(`String eventName`, `Function handler`, [`Object scope`], [`Object options`]) : void	Observable
	Appends an event handler to this component	Observable
	createNode() : void	TreeLoader
	Override this function for custom TreeNode node implementation	TreeLoader
	fireEvent(`String eventName`, `Object... args`) : Boolean	Observable
	Fires the specified event with the passed parameters (minus the event name).	Observable
	hasListener(`String eventName`) : Boolean	Observable
	Checks to see if this object has any listeners for a specified event	Observable
	load() : void	TreeLoader
	Load an Ext.tree.TreeNode from the URL specified in the constructor. This is called automatically when a node is expa...	TreeLoader
	on(`String eventName`, `Function handler`, [`Object scope`], [`Object options`]) : void	Observable
	Appends an event handler to this element (shorthand for addListener)	Observable
	purgeListeners() : void	Observable
	Removes all listeners for this object	Observable
	removeListener(`String eventName`, `Function handler`, [`Object scope`]) : void	Observable
	Removes a listener	Observable
	un(`String eventName`, `Function handler`, [`Object scope`]) : void	Observable
	Removes a listener (shorthand for removeListener)	Observable

Public Events

Event		Defined By
	beforeload : (`Object This`, `Object node`, `Object callback`)	TreeLoader
	Fires before a network request is made to retrieve the Json text which specifies a node's children.	TreeLoader
	load : (`Object This`, `Object node`, `Object response`)	TreeLoader
	Fires when the node has been successfuly loaded.	TreeLoader
	loadexception : (`Object This`, `Object node`, `Object response`)	TreeLoader
	Fires if the network request failed.	TreeLoader

Config Options

Config Options		Defined By
	baseParams : Object	TreeLoader
	(optional) An object containing properties which specify HTTP parameters to be passed to each request for child nodes.	TreeLoader
	clearOnLoad : Boolean	TreeLoader
	(optional) Default to true. Remove previously existing child nodes before loading.	TreeLoader
	dataUrl : String	TreeLoader
	The URL from which to request a Json string which specifies an array of node definition object representing the child...	TreeLoader
	uiProviders : Object	TreeLoader
	(optional) An object containing properties which specify custom Ext.tree.TreeNodeUI implementations. If the optional ...	TreeLoader

Constructor Details

TreeLoader

public function TreeLoader(Object config)

Creates a new Treeloader.

Parameters:

config : Object
A config object containing config properties.

Method Details

addEvents

public function addEvents(Object object)

Used to define events on this Observable

Parameters:

object : Object
The object with the events defined

Returns:

void

This method is defined by Observable.

addListener

public function addListener(String eventName, Function handler, [Object scope], [Object options])

Appends an event handler to this component

Parameters:

eventName : String
The type of event to listen for
handler : Function
The method the event invokes
scope : Object
(optional) The scope in which to execute the handler function. The handler function's "this" context.
options : Object
(optional) An object containing handler configuration properties. This may contain any of the following properties:
- scope {Object} The scope in which to execute the handler function. The handler function's "this" context.
- delay {Number} The number of milliseconds to delay the invocation of the handler after te event fires.
- single {Boolean} True to add a handler to handle just the next firing of the event, and then remove itself.
- buffer {Number} Causes the handler to be scheduled to run in an Ext.util.DelayedTask delayed by the specified number of milliseconds. If the event fires again within that time, the original handler is not invoked, but the new handler is scheduled in its place.
Combining Options
Using the options argument, it is possible to combine different types of listeners:

A normalized, delayed, one-time listener that auto stops the event and passes a custom argument (forumId)
Code:
```
 el.on('click', this.onClick, this, { single: true, delay: 100, forumId: 4 });
```
Attaching multiple handlers in 1 call
The method also allows for a single argument to be passed which is a config object containing properties which specify multiple handlers.
Code:
```
 foo.on({ 'click' : { fn: this.onClick scope: this, delay: 100 }, 'mouseover' : { fn: this.onMouseOver scope: this }, 'mouseout' : { fn: this.onMouseOut scope: this } });
```
Or a shorthand syntax:
Code:
```
 foo.on({ 'click' : this.onClick, 'mouseover' : this.onMouseOver, 'mouseout' : this.onMouseOut scope: this });
```

Returns:

void

This method is defined by Observable.

createNode

public function createNode()

Override this function for custom TreeNode node implementation

Parameters:

None.

Returns:

void

This method is defined by TreeLoader.

fireEvent

public function fireEvent(String eventName, Object... args)

Fires the specified event with the passed parameters (minus the event name).

Parameters:

eventName : String
args : Object...
Variable number of parameters are passed to handlers

Returns:

Boolean
returns false if any of the handlers return false otherwise it returns true

This method is defined by Observable.

hasListener

public function hasListener(String eventName)

Checks to see if this object has any listeners for a specified event

Parameters:

eventName : String
The name of the event to check for

Returns:

Boolean
True if the event is being listened for, else false

This method is defined by Observable.

load

public function load()

Load an Ext.tree.TreeNode from the URL specified in the constructor. This is called automatically when a node is expanded, but may be used to reload a node (or append new children if the clearOnLoad option is false.)

Parameters:

None.

Returns:

void

This method is defined by TreeLoader.

on

public function on(String eventName, Function handler, [Object scope], [Object options])

Appends an event handler to this element (shorthand for addListener)

Parameters:

eventName : String
The type of event to listen for
handler : Function
The method the event invokes
scope : Object
(optional) The scope in which to execute the handler function. The handler function's "this" context.
options : Object
(optional)

Returns:

void

This method is defined by Observable.

purgeListeners

public function purgeListeners()

Removes all listeners for this object

Parameters:

None.

Returns:

void

This method is defined by Observable.

removeListener

public function removeListener(String eventName, Function handler, [Object scope])

Removes a listener

Parameters:

eventName : String
The type of event to listen for
handler : Function
The handler to remove
scope : Object
(optional) The scope (this object) for the handler

Returns:

void

This method is defined by Observable.

un

public function un(String eventName, Function handler, [Object scope])

Removes a listener (shorthand for removeListener)

Parameters:

eventName : String
The type of event to listen for
handler : Function
The handler to remove
scope : Object
(optional) The scope (this object) for the handler

Returns:

void

This method is defined by Observable.

Event Details

beforeload

public event beforeload

Fires before a network request is made to retrieve the Json text which specifies a node's children.

Subscribers will be called with the following parameters:

This : Object
TreeLoader object.
node : Object
The Ext.tree.TreeNode object being loaded.
callback : Object
The callback function specified in the load call.

This event is defined by TreeLoader.

load

public event load

Fires when the node has been successfuly loaded.

Subscribers will be called with the following parameters:

This : Object
TreeLoader object.
node : Object
The Ext.tree.TreeNode object being loaded.
response : Object
The response object containing the data from the server.

This event is defined by TreeLoader.

loadexception

public event loadexception

Fires if the network request failed.

Subscribers will be called with the following parameters:

This : Object
TreeLoader object.
node : Object
The Ext.tree.TreeNode object being loaded.
response : Object
The response object containing the data from the server.

This event is defined by TreeLoader.

Config Details

baseParams

baseParams : Object

(optional) An object containing properties which specify HTTP parameters to be passed to each request for child nodes.

This config option is defined by TreeLoader.

clearOnLoad

clearOnLoad : Boolean

(optional) Default to true. Remove previously existing child nodes before loading.

This config option is defined by TreeLoader.

dataUrl

dataUrl : String

The URL from which to request a Json string which specifies an array of node definition object representing the child nodes to be loaded.

This config option is defined by TreeLoader.

uiProviders

uiProviders : Object

(optional) An object containing properties which specify custom Ext.tree.TreeNodeUI implementations. If the optional uiProvider attribute of a returned child node is a string rather than a reference to a TreeNodeUI implementation, this that string value is used as a property name in the uiProviders object.

This config option is defined by TreeLoader.