Yahoo! UI Library

DataSource Utility  2.2.0

Yahoo! UI Library > datasource > DataSource

Class DataSource - uses YAHOO.util.EventProvider

The DataSource class defines and manages a live set of data for widgets to interact with. Examples of live databases include in-memory local data such as a JavaScript array, a JavaScript function, or JSON, or remote data such as data retrieved through an XHR connection.

Constructor

DataSource ( oLiveData , oConfigs )
Parameters:
oLiveData <Object> Pointer to live database
oConfigs <Object> (optional) Object literal of configuration values

Properties

_aCache - private Object[]

Local cache of data result objects indexed chronologically.

_nIndex - private Number

Internal class variable to index multiple DataSource instances.

_sName - private String

Name of DataSource instance.

_xhrCallback - private object

Connection Manager callback object

connMgr - Object

Alias to YUI Connection Manager. Allows implementers to specify their own subclasses of the YUI Connection Manager utility.
Default Value: YAHOO.util.Connect

connTimeout - Number

If data is accessed over XHR via Connection Manager, the connection timeout is configurable in milliseconds the XHR connection will wait for a server response. A a value of zero indicates the XHR connection will wait forever. Any value greater than zero will use the Connection utility's Auto-Abort feature.
Default Value: 0

dataType - Number

Where the live data is held.
Default Value: YAHOO.util.DataSource.TYPE_UNKNOWN

ERROR_DATAINVALID - final String

Error message for invalid data responses.
Default Value: "Invalid data"

ERROR_DATANULL - final String

Error message for null data responses.
Default Value: "Null data"

liveData - Object

Pointer to live database.

maxCacheEntries - Number

Max size of the local cache. Set to 0 to turn off caching. Caching is useful to reduce the number of server connections. Recommended only for data sources that return comprehensive results for queries or when stale data is not an issue.
Default Value: 0

responseType - Number

Format of response.
Default Value: YAHOO.util.DataSource.TYPE_UNKNOWN

TYPE_JSARRAY - final Number

Type is a JavaScript Array.
Default Value: 0

TYPE_JSFUNCTIOn - final Number

Type is a JavaScript Function.
Default Value: 1

TYPE_JSON - final Number

Type is JSON.
Default Value: 3

TYPE_TEXT - final Number

Type is plain text.
Default Value: 5

TYPE_UNKNOWN - final Number

Type is unknown.
Default Value: -1

TYPE_XHR - final Number

Type is hosted on a server via an XHR connection.
Default Value: 2

TYPE_XML - final Number

Type is XML.
Default Value: 4

Properties inherited from YAHOO.util.EventProvider:

__yui_events, __yui_subscribers

Methods

_xhrFailure

private void _xhrFailure ( oResponse )
Connection Manager failure handler
Parameters:
oResponse <Object> HTTPXMLRequest object
Returns: void

_xhrSuccess

private void _xhrSuccess ( oResponse )
Connection Manager success handler
Parameters:
oResponse <Object> HTTPXMLRequest object
Returns: void

addToCache

void addToCache ( oRequest , oResponse )
Adds a new item to the cache. If cache is full, evicts the stalest item before adding the new item.
Parameters:
oRequest <Object> Request object.
oResponse <Object> Response object to cache.
Returns: void

flushCache

void flushCache ( )
Flushes cache.
Returns: void

getCachedResponse

Object getCachedResponse ( oRequest , oCallback , oCaller )
Overridable method passes request to cache and returns cached response if any, refreshing the hit in the cache as the newest item. Returns null if there is no cache hit.
Parameters:
oRequest <Object> Request object.
oCallback <Function> Handler function to receive the response
oCaller <Object> The Calling object that is making the request
Returns: Object
Cached response object or null.

handleResponse

void handleResponse ( oRequest , oRawResponse , oCallback , oCaller )
Handles raw data response from live data source.
Parameters:
oRequest <Object> Request object
oRawResponse <Object> The raw response from the live database
oCallback <Function> Handler function to receive the response
oCaller <Object> The calling object that is making the request
Returns: void

isCacheHit

Boolean isCacheHit ( oRequest , oCachedRequest )
Default overridable method matches given request to given cached request. Returns true if is a hit, returns false otherwise. Implementers should override this method to customize the cache-matching algorithm.
Parameters:
oRequest <Object> Request object.
oCachedRequest <Object> Cached request object.
Returns: Boolean
True if given request matches cached request, false otherwise.

makeConnection

void makeConnection ( oRequest , oCallback , oCaller )
Overridable method provides default functionality to make a connection to live data in order to send request. The response coming back is then forwarded to the handleResponse function. This method should be customized for more complex implementations.
Parameters:
oRequest <Object> Request object.
oCallback <Function> Handler function to receive the response
oCaller <Object> The Calling object that is making the request
Returns: void

parseArrayData

Object parseArrayData ( oRequest , oRawResponse )
Overridable method parses raw array data into a response object.
Parameters:
oRequest <Object> Request object.
oRawResponse <Object> The raw response from the live database
Returns: Object
Parsed response object

parseJSONData

Object parseJSONData ( oRequest , oRawResponse )
Overridable method parses raw JSON data into a response object.
Parameters:
oRequest <Object> Request object
oRawResponse <Object> The raw response from the live database
Returns: Object
Parsed response object

parseTextData

Object parseTextData ( oRequest , oRawResponse )
Overridable method parses raw plain text data into a response object.
Parameters:
oRequest <Object> Request object
oRawResponse <Object> The raw response from the live database
Returns: Object
Parsed response object

parseXMLData

Object parseXMLData ( oRequest , oRawResponse )
Overridable method parses raw XML data into a response object.
Parameters:
oRequest <Object> Request object
oRawResponse <Object> The raw response from the live database
Returns: Object
Parsed response object

sendRequest

void sendRequest ( oRequest , oCallback , oCaller )
First looks for cached response, then sends request to live data.
Parameters:
oRequest <Object> Request object
oCallback <Function> Handler function to receive the response
oCaller <Object> The Calling object that is making the request
Returns: void

toString

String toString ( )
Public accessor to the unique name of the DataSource instance.
Returns: String
Unique name of the DataSource instance.

Methods inherited from YAHOO.util.EventProvider:

createEvent, fireEvent, hasEvent, subscribe, unsubscribe, unsubscribeAll

Events

cacheFlushEvent

cacheFlushEvent ( )
Fired when the local cache is flushed.

cacheRequestEvent

cacheRequestEvent ( oArgs.request , oArgs.callback , oArgs.caller )
Fired when a request is made to the local cache.
Parameters:
oArgs.request <Object> The request object.
oArgs.callback <Function> The callback function.
oArgs.caller <Object> The parent object of the callback function.

dataErrorEvent

dataErrorEvent ( oArgs.request , oArgs.callback , oArgs.caller , oArgs.message )
Fired when an error is encountered with the live data source.
Parameters:
oArgs.request <Object> The request object.
oArgs.callback <Function> The callback function.
oArgs.caller <Object> The parent object of the callback function.
oArgs.message <String> The error message.

getCachedResponseEvent

getCachedResponseEvent ( oArgs.request , oArgs.response , oArgs.callback , oArgs.caller )
Fired when data is retrieved from the local cache.
Parameters:
oArgs.request <Object> The request object.
oArgs.response <Object> The response object.
oArgs.callback <Function> The callback function.
oArgs.caller <Object> The parent object of the callback function.

parseResponseEvent

parseResponseEvent ( oArgs.request , oArgs.response , oArgs.callback , oArgs.caller )
Fired when live data source sends response.
Parameters:
oArgs.request <Object> The request object.
oArgs.response <Object> The raw response object.
oArgs.callback <Function> The callback function.
oArgs.caller <Object> The parent object of the callback function.

requestEvent

requestEvent ( oArgs.request , oArgs.callback , oArgs.caller )
Fired when a request is sent to the live data source.
Parameters:
oArgs.request <Object> The request object.
oArgs.callback <Function> The callback function.
oArgs.caller <Object> The parent object of the callback function.

responseCacheEvent

responseCacheEvent ( oArgs.request , oArgs.response , oArgs.callback , oArgs.caller )
Fired when response is cached.
Parameters:
oArgs.request <Object> The request object.
oArgs.response <Object> The parsed response object.
oArgs.callback <Function> The callback function.
oArgs.caller <Object> The parent object of the callback function.

responseParseEvent

responseParseEvent ( oArgs.request , oArgs.response , oArgs.callback , oArgs.caller )
Fired when response is parsed.
Parameters:
oArgs.request <Object> The request object.
oArgs.response <Object> The parsed response object.
oArgs.callback <Function> The callback function.
oArgs.caller <Object> The parent object of the callback function.

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