/* Copyright (c) 2007, Yahoo! Inc. All rights reserved. Code licensed under the BSD License: http://developer.yahoo.net/yui/license.txt version: 2.2.0 */ /** * The DataSource utility provides a common configurable interface for widgets * to access a variety of data, from JavaScript arrays to online servers over * XHR. * * @module datasource * @requires yahoo, event * @optional xhr * @title DataSource Utility * @beta */ /****************************************************************************/ /****************************************************************************/ /****************************************************************************/ /** * 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. * * @class DataSource * @uses YAHOO.util.EventProvider * @constructor * @param oLiveData {Object} Pointer to live database * @param oConfigs {Object} (optional) Object literal of configuration values */ YAHOO.util.DataSource = function(oLiveData, oConfigs) { // Set any config params passed in to override defaults if(typeof oConfigs == "object") { for(var sConfig in oConfigs) { if (sConfig) { this[sConfig] = oConfigs[sConfig]; } } } if(!oLiveData) { YAHOO.log("Could not instantiate DataSource due to invalid live database.","error",this.toString()); return; } else { switch(oLiveData.constructor) { case Function: this.dataType = YAHOO.util.DataSource.TYPE_JSFUNCTION; break; case Array: this.dataType = YAHOO.util.DataSource.TYPE_JSARRAY; break; case String: this.dataType = YAHOO.util.DataSource.TYPE_XHR; break; case Object: this.dataType = YAHOO.util.DataSource.TYPE_JSON; break; default: this.dataType = YAHOO.util.DataSource.TYPE_UNKNOWN; break; } this.liveData = oLiveData; } // Validate and initialize public configs var maxCacheEntries = this.maxCacheEntries; if(isNaN(maxCacheEntries) || (maxCacheEntries < 0)) { maxCacheEntries = 0; } // Initialize local cache if(maxCacheEntries > 0 && !this._aCache) { this._aCache = []; YAHOO.log("Cache initialized","info",this.toString()); } this._sName = "instance" + YAHOO.util.DataSource._nIndex; YAHOO.util.DataSource._nIndex++; YAHOO.log("DataSource initialized", "info", this.toString()); ///////////////////////////////////////////////////////////////////////////// // // Custom Events // ///////////////////////////////////////////////////////////////////////////// /** * Fired when a request is made to the local cache. * * @event cacheRequestEvent * @param oArgs.request {Object} The request object. * @param oArgs.callback {Function} The callback function. * @param oArgs.caller {Object} The parent object of the callback function. */ this.createEvent("cacheRequestEvent"); /** * Fired when data is retrieved from the local cache. * * @event getCachedResponseEvent * @param oArgs.request {Object} The request object. * @param oArgs.response {Object} The response object. * @param oArgs.callback {Function} The callback function. * @param oArgs.caller {Object} The parent object of the callback function. */ this.createEvent("cacheResponseEvent"); /** * Fired when a request is sent to the live data source. * * @event requestEvent * @param oArgs.request {Object} The request object. * @param oArgs.callback {Function} The callback function. * @param oArgs.caller {Object} The parent object of the callback function. */ this.createEvent("requestEvent"); /** * Fired when live data source sends response. * * @event parseResponseEvent * @param oArgs.request {Object} The request object. * @param oArgs.response {Object} The raw response object. * @param oArgs.callback {Function} The callback function. * @param oArgs.caller {Object} The parent object of the callback function. */ this.createEvent("responseEvent"); /** * Fired when response is parsed. * * @event responseParseEvent * @param oArgs.request {Object} The request object. * @param oArgs.response {Object} The parsed response object. * @param oArgs.callback {Function} The callback function. * @param oArgs.caller {Object} The parent object of the callback function. */ this.createEvent("responseParseEvent"); /** * Fired when response is cached. * * @event responseCacheEvent * @param oArgs.request {Object} The request object. * @param oArgs.response {Object} The parsed response object. * @param oArgs.callback {Function} The callback function. * @param oArgs.caller {Object} The parent object of the callback function. */ this.createEvent("responseCacheEvent"); /** * Fired when an error is encountered with the live data source. * * @event dataErrorEvent * @param oArgs.request {Object} The request object. * @param oArgs.callback {Function} The callback function. * @param oArgs.caller {Object} The parent object of the callback function. * @param oArgs.message {String} The error message. */ this.createEvent("dataErrorEvent"); /** * Fired when the local cache is flushed. * * @event cacheFlushEvent */ this.createEvent("cacheFlushEvent"); }; YAHOO.augment(YAHOO.util.DataSource, YAHOO.util.EventProvider); ///////////////////////////////////////////////////////////////////////////// // // Public constants // ///////////////////////////////////////////////////////////////////////////// /** * Type is unknown. * * @property TYPE_UNKNOWN * @type Number * @final * @default -1 */ YAHOO.util.DataSource.TYPE_UNKNOWN = -1; /** * Type is a JavaScript Array. * * @property TYPE_JSARRAY * @type Number * @final * @default 0 */ YAHOO.util.DataSource.TYPE_JSARRAY = 0; /** * Type is a JavaScript Function. * * @property TYPE_JSFUNCTIOn * @type Number * @final * @default 1 */ YAHOO.util.DataSource.TYPE_JSFUNCTION = 1; /** * Type is hosted on a server via an XHR connection. * * @property TYPE_XHR * @type Number * @final * @default 2 */ YAHOO.util.DataSource.TYPE_XHR = 2; /** * Type is JSON. * * @property TYPE_JSON * @type Number * @final * @default 3 */ YAHOO.util.DataSource.TYPE_JSON = 3; /** * Type is XML. * * @property TYPE_XML * @type Number * @final * @default 4 */ YAHOO.util.DataSource.TYPE_XML = 4; /** * Type is plain text. * * @property TYPE_TEXT * @type Number * @final * @default 5 */ YAHOO.util.DataSource.TYPE_TEXT = 5; /** * Error message for invalid data responses. * * @property ERROR_DATAINVALID * @type String * @final * @default "Invalid data" */ YAHOO.util.DataSource.ERROR_DATAINVALID = "Invalid data"; /** * Error message for null data responses. * * @property ERROR_DATANULL * @type String * @final * @default "Null data" */ YAHOO.util.DataSource.ERROR_DATANULL = "Null data"; ///////////////////////////////////////////////////////////////////////////// // // Private member variables // ///////////////////////////////////////////////////////////////////////////// /** * Internal class variable to index multiple DataSource instances. * * @property _nIndex * @type Number * @private */ YAHOO.util.DataSource._nIndex = 0; /** * Name of DataSource instance. * * @property _sName * @type String * @private */ YAHOO.util.DataSource.prototype._sName = null; /** * Local cache of data result objects indexed chronologically. * * @property _aCache * @type Object[] * @private */ YAHOO.util.DataSource.prototype._aCache = null; ///////////////////////////////////////////////////////////////////////////// // // Private methods // ///////////////////////////////////////////////////////////////////////////// ///////////////////////////////////////////////////////////////////////////// // // Public member variables // ///////////////////////////////////////////////////////////////////////////// /** * 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. * * @property maxCacheEntries * @type Number * @default 0 */ YAHOO.util.DataSource.prototype.maxCacheEntries = 0; /** * Pointer to live database. * * @property liveData * @type Object */ YAHOO.util.DataSource.prototype.liveData = null; /** * 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. * * @property connTimeout * @type Number * @default 0 */ YAHOO.util.DataSource.prototype.connTimeout = null; /** * Alias to YUI Connection Manager. Allows implementers to specify their own * subclasses of the YUI Connection Manager utility. * * @property connMgr * @type Object * @default YAHOO.util.Connect */ YAHOO.util.DataSource.prototype.connMgr = YAHOO.util.Connect || null; /** * Where the live data is held. * * @property dataType * @type Number * @default YAHOO.util.DataSource.TYPE_UNKNOWN * */ YAHOO.util.DataSource.prototype.dataType = YAHOO.util.DataSource.TYPE_UNKNOWN; /** * Format of response. * * @property responseType * @type Number * @default YAHOO.util.DataSource.TYPE_UNKNOWN */ YAHOO.util.DataSource.prototype.responseType = YAHOO.util.DataSource.TYPE_UNKNOWN; ///////////////////////////////////////////////////////////////////////////// // // Public methods // ///////////////////////////////////////////////////////////////////////////// /** * Public accessor to the unique name of the DataSource instance. * * @method toString * @return {String} Unique name of the DataSource instance. */ YAHOO.util.DataSource.prototype.toString = function() { return "DataSource " + this._sName; }; /** * 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. * * @method getCachedResponse * @param oRequest {Object} Request object. * @param oCallback {Function} Handler function to receive the response * @param oCaller {Object} The Calling object that is making the request * @return {Object} Cached response object or null. */ YAHOO.util.DataSource.prototype.getCachedResponse = function(oRequest, oCallback, oCaller) { var aCache = this._aCache; var nCacheLength = (aCache) ? aCache.length : 0; var oResponse = null; // If cache is enabled... if((this.maxCacheEntries > 0) && aCache && (nCacheLength > 0)) { this.fireEvent("cacheRequestEvent", {request:oRequest,callback:oCallback,caller:oCaller}); // Loop through each cached element for(var i = nCacheLength-1; i >= 0; i--) { var oCacheElem = aCache[i]; // Defer cache hit logic to a public overridable method if(this.isCacheHit(oRequest,oCacheElem.request)) { // Grab the cached response oResponse = oCacheElem.response; // The cache returned a hit! // Remove element from its original location aCache.splice(i,1); // Add as newest this.addToCache(oRequest, oResponse); this.fireEvent("cacheResponseEvent", {request:oRequest,response:oResponse,callback:oCallback,caller:oCaller}); break; } } } return oResponse; }; /** * 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. * * @method isCacheHit * @param oRequest {Object} Request object. * @param oCachedRequest {Object} Cached request object. * @return {Boolean} True if given request matches cached request, false otherwise. */ YAHOO.util.DataSource.prototype.isCacheHit = function(oRequest, oCachedRequest) { return (oRequest === oCachedRequest); }; /** * Adds a new item to the cache. If cache is full, evicts the stalest item * before adding the new item. * * @method addToCache * @param oRequest {Object} Request object. * @param oResponse {Object} Response object to cache. */ YAHOO.util.DataSource.prototype.addToCache = function(oRequest, oResponse) { //TODO: check for duplicate entries var aCache = this._aCache; // Don't add if anything important is missing. if(!aCache || !oRequest || !oResponse) { return; } // If the cache is full, make room by removing stalest element (index=0) while(aCache.length >= this.maxCacheEntries) { aCache.shift(); } // Add to cache in the newest position, at the end of the array var oCacheElem = {request:oRequest,response:oResponse}; aCache.push(oCacheElem); this.fireEvent("responseCacheEvent",{request:oRequest,response:oResponse}); }; /** * Flushes cache. * * @method flushCache */ YAHOO.util.DataSource.prototype.flushCache = function() { if(this._aCache) { this._aCache = []; } this.fireEvent("cacheFlushEvent"); }; /** * First looks for cached response, then sends request to live data. * * @method sendRequest * @param oRequest {Object} Request object * @param oCallback {Function} Handler function to receive the response * @param oCaller {Object} The Calling object that is making the request */ YAHOO.util.DataSource.prototype.sendRequest = function(oRequest, oCallback, oCaller) { // First look in cache var oCachedResponse = this.getCachedResponse(oRequest, oCallback, oCaller); if(oCachedResponse) { oCallback.call(oCaller, oRequest, oCachedResponse); return; } // Not in cache, so forward request to live data this.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. * * @method makeConnection * @param oRequest {Object} Request object. * @param oCallback {Function} Handler function to receive the response * @param oCaller {Object} The Calling object that is making the request */ YAHOO.util.DataSource.prototype.makeConnection = function(oRequest, oCallback, oCaller) { this.fireEvent("requestEvent", {request:oRequest,callback:oCallback,caller:oCaller}); var oRawResponse = null; // How to make the connection depends on the type of data switch(this.dataType) { // If the live data is a JavaScript Array // simply forward the entire array to the handler case YAHOO.util.DataSource.TYPE_JSARRAY: case YAHOO.util.DataSource.TYPE_JSON: oRawResponse = this.liveData; this.handleResponse(oRequest, oRawResponse, oCallback, oCaller); break; // If the live data is a JavaScript Function // pass the request in as a parameter and // forward the return value to the handler case YAHOO.util.DataSource.TYPE_JSFUNCTION: oRawResponse = this.liveData(oRequest); this.handleResponse(oRequest, oRawResponse, oCallback, oCaller); break; // If the live data is over Connection Manager // set up the callback object and // pass the request in as a URL query and // forward the response to the handler case YAHOO.util.DataSource.TYPE_XHR: /** * Connection Manager success handler * * @method _xhrSuccess * @param oResponse {Object} HTTPXMLRequest object * @private */ var _xhrSuccess = function(oResponse) { // Error if no response if(!oResponse) { this.fireEvent("dataErrorEvent", {request:oRequest,callback:oCallback,caller:oCaller,message:YAHOO.util.DataSource.ERROR_DATANULL}); YAHOO.log(YAHOO.util.DataSource.ERROR_DATANULL, "error", this.toString()); return null; } // Error if response ID does not match last made request ID. else if(!this._oConn || (oResponse.tId != this._oConn.tId)) { this.fireEvent("dataErrorEvent", {request:oRequest,callback:oCallback,caller:oCaller,message:YAHOO.util.DataSource.ERROR_DATAINVALID}); YAHOO.log(YAHOO.util.DataSource.ERROR_DATAINVALID, "error", this.toString()); return null; } // Forward to handler else { this.handleResponse(oRequest, oResponse, oCallback, oCaller); } }; /** * Connection Manager failure handler * * @method _xhrFailure * @param oResponse {Object} HTTPXMLRequest object * @private */ var _xhrFailure = function(oResponse) { this.fireEvent("dataErrorEvent", {request:oRequest,callback:oCallback,caller:oCaller,message:YAHOO.util.DataSource.ERROR_DATAXHR}); YAHOO.log(this.ERROR_DATAXHR + ": " + oResp.statusText, "error", this.toString()); return null; }; /** * Connection Manager callback object * * @property _xhrCallback * @param oResponse {Object} HTTPXMLRequest object * @private */ var _xhrCallback = { success:_xhrSuccess, failure:_xhrFailure, scope: this }; //TODO: connTimeout config if(this.connTimeout && !isNaN(this.connTimeout) && this.connTimeout > 0) { _xhrCallback.timeout = this.connTimeout; } //TODO: oConn config if(this._oConn && this.connMgr) { this.connMgr.abort(this._oConn); } var sUri = this.liveData+"?"+oRequest; if(this.connMgr) { this._oConn = this.connMgr.asyncRequest("GET", sUri, _xhrCallback, null); } else { YAHOO.log("Could not find a valid Connection Manager","error",this.toString()); } break; default: //TODO: any default? break; } }; /** * Handles raw data response from live data source. * * @method handleResponse * @param oRequest {Object} Request object * @param oRawResponse {Object} The raw response from the live database * @param oCallback {Function} Handler function to receive the response * @param oCaller {Object} The calling object that is making the request */ YAHOO.util.DataSource.prototype.handleResponse = function(oRequest, oRawResponse, oCallback, oCaller) { this.fireEvent("responseEvent", {request:oRequest,response:oRawResponse,callback:oCallback,caller:oCaller}); var xhr = (this.dataType == YAHOO.util.DataSource.TYPE_XHR) ? true : false; var oParsedResponse = null; //TODO: break out into overridable methods switch(this.responseType) { case YAHOO.util.DataSource.TYPE_JSARRAY: if(xhr && oRawResponse.responseText) { oRawResponse = oRawResponse.responseText; } oParsedResponse = this.parseArrayData(oRequest, oRawResponse); break; case YAHOO.util.DataSource.TYPE_JSON: if(xhr && oRawResponse.responseText) { oRawResponse = oRawResponse.responseText; } oParsedResponse = this.parseJSONData(oRequest, oRawResponse); break; case YAHOO.util.DataSource.TYPE_XML: if(xhr && oRawResponse.responseXML) { oRawResponse = oRawResponse.responseXML; } oParsedResponse = this.parseXMLData(oRequest, oRawResponse); break; case YAHOO.util.DataSource.TYPE_TEXT: if(xhr && oRawResponse.responseText) { oRawResponse = oRawResponse.responseText; } oParsedResponse = this.parseTextData(oRequest, oRawResponse); break; default: //TODO: pass off to custom function //var contentType = oRawResponse.getResponseHeader["Content-Type"]; YAHOO.log("Unknown response type","warn",this.toStrin()); break; } if(oParsedResponse) { this.fireEvent("responseParseEvent", {request:oRequest,response:oParsedResponse,callback:oCallback,caller:oCaller}); // Cache the response this.addToCache(oRequest, oParsedResponse); } else { this.fireEvent("dataErrorEvent", {request:oRequest,callback:oCallback,caller:oCaller,message:YAHOO.util.DataSource.ERROR_DATANULL}); YAHOO.log(YAHOO.util.DataSource.ERROR_DATANULL, "error", this.toString()); } // Send the response back to the caller oCallback.call(oCaller, oRequest, oParsedResponse); }; /** * Overridable method parses raw array data into a response object. * * @method parseArrayData * @param oRequest {Object} Request object. * @param oRawResponse {Object} The raw response from the live database * @return {Object} Parsed response object */ YAHOO.util.DataSource.prototype.parseArrayData = function(oRequest, oRawResponse) { var oParsedResponse = []; var fields = this.responseSchema.fields; for(var i=oRawResponse.length-1; i>-1; i--) { var oResult = {}; for(var j=fields.length; j>-1; j--) { oResult[fields[j]] = oRawResponse[i][j] || oRawResponse[i][fields[j]]; } oParsedResponse.unshift(oResult); } return oParsedResponse; }; /** * Overridable method parses raw plain text data into a response object. * * @method parseTextData * @param oRequest {Object} Request object * @param oRawResponse {Object} The raw response from the live database * @return {Object} Parsed response object */ YAHOO.util.DataSource.prototype.parseTextData = function(oRequest, oRawResponse) { var oParsedResponse = []; var recDelim = this.responseSchema.recordDelim; var fieldDelim = this.responseSchema.fieldDelim; var aSchema = this.responseSchema.fields; if(oRawResponse.length > 0) { // Delete the last line delimiter at the end of the data if it exists var newLength = oRawResponse.length-recDelim.length; if(oRawResponse.substr(newLength) == recDelim) { oRawResponse = oRawResponse.substr(0, newLength); } // Split along record delimiter to get an array of strings var recordsarray = oRawResponse.split(recDelim); // Cycle through each record, except the first which contains header info for(var i = recordsarray.length-1; i >= 1; i--) { var dataobject = {}; for(var j=aSchema.length-1; j >= 0; j--) { // Split along field delimter to get each data value var fielddataarray = recordsarray[i].split(fieldDelim); // Remove quotation marks from edges, if applicable var string = fielddataarray[j]; if(string.charAt(0) == "\"") { string = string.substr(1); } if(string.charAt(string.length-1) == "\"") { string = string.substr(0,string.length-1); } dataobject[aSchema[j]] = string; } oParsedResponse.push(dataobject); } } return oParsedResponse; }; /** * Overridable method parses raw XML data into a response object. * * @method parseXMLData * @param oRequest {Object} Request object * @param oRawResponse {Object} The raw response from the live database * @return {Object} Parsed response object */ YAHOO.util.DataSource.prototype.parseXMLData = function(oRequest, oRawResponse) { var bError = false; var oParsedResponse = []; var xmlList = oRawResponse.getElementsByTagName(this.responseSchema.resultNode); if(!xmlList) { bError = true; } // Loop through each result else { for(var k = xmlList.length-1; k >= 0 ; k--) { var result = xmlList.item(k); var oResult = {}; // Loop through each data field in each result using the schema for(var m = this.responseSchema.fields.length-1; m >= 0 ; m--) { var field = this.responseSchema.fields[m]; var sValue = null; // Values may be held in an attribute... var xmlAttr = result.attributes.getNamedItem(field); if(xmlAttr) { sValue = xmlAttr.value; } // ...or in a node else { var xmlNode = result.getElementsByTagName(field); if(xmlNode && xmlNode.item(0) && xmlNode.item(0).firstChild) { sValue = xmlNode.item(0).firstChild.nodeValue; } else { sValue = ""; } } // Capture the schema-mapped data field values into an array oResult[field] = sValue; } // Capture each array of values into an array of results oParsedResponse.unshift(oResult); } } if(bError) { return null; } return oParsedResponse; }; /** * Overridable method parses raw JSON data into a response object. * * @method parseJSONData * @param oRequest {Object} Request object * @param oRawResponse {Object} The raw response from the live database * @return {Object} Parsed response object */ YAHOO.util.DataSource.prototype.parseJSONData = function(oRequest, oRawResponse) { //TODO: validate oRawResponse var bError = false; var oParsedResponse = []; var aSchema = this.responseSchema.fields; var jsonObj,jsonList; if(oRawResponse) { // Parse JSON object out if it's a string if(oRawResponse.constructor == String) { // Check for latest JSON lib but divert KHTML clients if(oRawResponse.parseJSON && (navigator.userAgent.toLowerCase().indexOf('khtml')== -1)) { // Use the new JSON utility if available jsonObj = oRawResponse.parseJSON(); if(!jsonObj) { bError = true; } } // Check for older JSON lib but divert KHTML clients else if(window.JSON && JSON.parse && (navigator.userAgent.toLowerCase().indexOf('khtml')== -1)) { // Use the JSON utility if available jsonObj = JSON.parse(oRawResponse); if(!jsonObj) { bError = true; } } // No JSON lib found so parse the string else { try { // Trim leading spaces while (oRawResponse.length > 0 && (oRawResponse.charAt(0) != "{") && (oRawResponse.charAt(0) != "[")) { oRawResponse = oRawResponse.substring(1, oResponse.length); } if(oRawResponse.length > 0) { // Strip extraneous stuff at the end var objEnd = Math.max(oRawResponse.lastIndexOf("]"),oRawResponse.lastIndexOf("}")); oRawResponse = oRawResponse.substring(0,objEnd+1); // Turn the string into an object literal... // ...eval is necessary here jsonObj = eval("(" + oRawResponse + ")"); if(!jsonObj) { bError = true; } } } catch(e) { bError = true; } } } // Response must already be a JSON object else if(oRawResponse.constructor == Object) { jsonObj = oRawResponse; } // Now that we have a JSON object, parse a jsonList out of it if(jsonObj && jsonObj.constructor == Object) { try { // eval is necessary here since schema can be of unknown depth jsonList = eval("jsonObj." + this.responseSchema.resultsList); } catch(e) { bError = true; } } } if(bError || !jsonList) { // Something went wrong return null; } if(jsonList.constructor != Array) { jsonList = [jsonList]; } // Loop through the array of all responses... for(var i = jsonList.length-1; i >= 0 ; i--) { var oResult = {}; var jsonResult = jsonList[i]; // ...and loop through each data field value of each response for(var j = aSchema.length-1; j >= 0 ; j--) { // ...and capture data into an array mapped according to the schema... var dataFieldValue = jsonResult[aSchema[j]]; if(!dataFieldValue) { dataFieldValue = ""; } //YAHOO.log("data: " + i + " value:" +j+" = "+dataFieldValue,"debug",this.toString()); oResult[aSchema[j]] = dataFieldValue; } // Capture the array of data field values in an array of results oParsedResponse.unshift(oResult); } return oParsedResponse; }; YAHOO.register("datasource", YAHOO.util.DataSource, {version: "2.2.0", build: "127"});