/*!
 * Ext JS Library 3.3.0
 * Copyright(c) 2006-2010 Ext JS, Inc.
 * licensing@extjs.com
 * http://www.extjs.com/license
 */
/** * @class Ext.data.ScriptTagProxy * @extends Ext.data.DataProxy * An implementation of Ext.data.DataProxy that reads a data object from a URL which may be in a domain * other than the originating domain of the running page.
*

* Note that if you are retrieving data from a page that is in a domain that is NOT the same as the originating domain * of the running page, you must use this class, rather than HttpProxy.
*

* The content passed back from a server resource requested by a ScriptTagProxy must be executable JavaScript * source code because it is used as the source inside a <script> tag.
*

* In order for the browser to process the returned data, the server must wrap the data object * with a call to a callback function, the name of which is passed as a parameter by the ScriptTagProxy. * Below is a Java example for a servlet which returns data for either a ScriptTagProxy, or an HttpProxy * depending on whether the callback name was passed: *

*


boolean scriptTag = false;
String cb = request.getParameter("callback");
if (cb != null) {
    scriptTag = true;
    response.setContentType("text/javascript");
} else {
    response.setContentType("application/x-json");
}
Writer out = response.getWriter();
if (scriptTag) {
    out.write(cb + "(");
}
out.print(dataBlock.toJsonString());
if (scriptTag) {
    out.write(");");
}
*

Below is a PHP example to do the same thing:


$callback = $_REQUEST['callback'];

// Create the output object.
$output = array('a' => 'Apple', 'b' => 'Banana');

//start output
if ($callback) {
    header('Content-Type: text/javascript');
    echo $callback . '(' . json_encode($output) . ');';
} else {
    header('Content-Type: application/x-json');
    echo json_encode($output);
}
*

Below is the ASP.Net code to do the same thing:


String jsonString = "{success: true}";
String cb = Request.Params.Get("callback");
String responseString = "";
if (!String.IsNullOrEmpty(cb)) {
    responseString = cb + "(" + jsonString + ")";
} else {
    responseString = jsonString;
}
Response.Write(responseString);
* * @constructor * @param {Object} config A configuration object. */ Ext.data.ScriptTagProxy = function(config){ Ext.apply(this, config); Ext.data.ScriptTagProxy.superclass.constructor.call(this, config); this.head = document.getElementsByTagName("head")[0];
/** * @event loadexception * Deprecated in favor of 'exception' event. * Fires if an exception occurs in the Proxy during data loading. This event can be fired for one of two reasons: * * Note that this event is also relayed through {@link Ext.data.Store}, so you can listen for it directly * on any Store instance. * @param {Object} this * @param {Object} options The loading options that were specified (see {@link #load} for details). If the load * call timed out, this parameter will be null. * @param {Object} arg The callback's arg object passed to the {@link #load} function * @param {Error} e The JavaScript Error object caught if the configured Reader could not read the data. * If the remote request returns success: false, this parameter will be null. */ }; Ext.data.ScriptTagProxy.TRANS_ID = 1000; Ext.extend(Ext.data.ScriptTagProxy, Ext.data.DataProxy, {
/** * @cfg {String} url The URL from which to request the data object. */
/** * @cfg {Number} timeout (optional) The number of milliseconds to wait for a response. Defaults to 30 seconds. */ timeout : 30000,
/** * @cfg {String} callbackParam (Optional) The name of the parameter to pass to the server which tells * the server the name of the callback function set up by the load call to process the returned data object. * Defaults to "callback".

The server-side processing must read this parameter value, and generate * javascript output which calls this named function passing the data object as its only parameter. */ callbackParam : "callback",

/** * @cfg {Boolean} nocache (optional) Defaults to true. Disable caching by adding a unique parameter * name to the request. */ nocache : true,
/** * HttpProxy implementation of DataProxy#doRequest * @param {String} action * @param {Ext.data.Record/Ext.data.Record[]} rs If action is read, rs will be null * @param {Object} params An object containing properties which are to be used as HTTP parameters * for the request to the remote server. * @param {Ext.data.DataReader} reader The Reader object which converts the data * object into a block of Ext.data.Records. * @param {Function} callback The function into which to pass the block of Ext.data.Records. * The function must be passed * @param {Object} scope The scope (this reference) in which the callback function is executed. Defaults to the browser window. * @param {Object} arg An optional argument which is passed to the callback as its second parameter. */ doRequest : function(action, rs, params, reader, callback, scope, arg) { var p = Ext.urlEncode(Ext.apply(params, this.extraParams)); var url = this.buildUrl(action, rs); if (!url) { throw new Ext.data.Api.Error('invalid-url', url); } url = Ext.urlAppend(url, p); if(this.nocache){ url = Ext.urlAppend(url, '_dc=' + (new Date().getTime())); } var transId = ++Ext.data.ScriptTagProxy.TRANS_ID; var trans = { id : transId, action: action, cb : "stcCallback"+transId, scriptId : "stcScript"+transId, params : params, arg : arg, url : url, callback : callback, scope : scope, reader : reader }; window[trans.cb] = this.createCallback(action, rs, trans); url += String.format("&{0}={1}", this.callbackParam, trans.cb); if(this.autoAbort !== false){ this.abort(); } trans.timeoutId = this.handleFailure.defer(this.timeout, this, [trans]); var script = document.createElement("script"); script.setAttribute("src", url); script.setAttribute("type", "text/javascript"); script.setAttribute("id", trans.scriptId); this.head.appendChild(script); this.trans = trans; }, // @private createCallback createCallback : function(action, rs, trans) { var self = this; return function(res) { self.trans = false; self.destroyTrans(trans, true); if (action === Ext.data.Api.actions.read) { self.onRead.call(self, action, trans, res); } else { self.onWrite.call(self, action, trans, res, rs); } }; },
/** * Callback for read actions * @param {String} action [Ext.data.Api.actions.create|read|update|destroy] * @param {Object} trans The request transaction object * @param {Object} res The server response * @protected */ onRead : function(action, trans, res) { var result; try { result = trans.reader.readRecords(res); }catch(e){ // @deprecated: fire loadexception this.fireEvent("loadexception", this, trans, res, e); this.fireEvent('exception', this, 'response', action, trans, res, e); trans.callback.call(trans.scope||window, null, trans.arg, false); return; } if (result.success === false) { // @deprecated: fire old loadexception for backwards-compat. this.fireEvent('loadexception', this, trans, res); this.fireEvent('exception', this, 'remote', action, trans, res, null); } else { this.fireEvent("load", this, res, trans.arg); } trans.callback.call(trans.scope||window, result, trans.arg, result.success); },
/** * Callback for write actions * @param {String} action [Ext.data.Api.actions.create|read|update|destroy] * @param {Object} trans The request transaction object * @param {Object} res The server response * @protected */ onWrite : function(action, trans, response, rs) { var reader = trans.reader; try { // though we already have a response object here in STP, run through readResponse to catch any meta-data exceptions. var res = reader.readResponse(action, response); } catch (e) { this.fireEvent('exception', this, 'response', action, trans, res, e); trans.callback.call(trans.scope||window, null, res, false); return; } if(!res.success === true){ this.fireEvent('exception', this, 'remote', action, trans, res, rs); trans.callback.call(trans.scope||window, null, res, false); return; } this.fireEvent("write", this, action, res.data, res, rs, trans.arg ); trans.callback.call(trans.scope||window, res.data, res, true); }, // private isLoading : function(){ return this.trans ? true : false; },
/** * Abort the current server request. */ abort : function(){ if(this.isLoading()){ this.destroyTrans(this.trans); } }, // private destroyTrans : function(trans, isLoaded){ this.head.removeChild(document.getElementById(trans.scriptId)); clearTimeout(trans.timeoutId); if(isLoaded){ window[trans.cb] = undefined; try{ delete window[trans.cb]; }catch(e){} }else{ // if hasn't been loaded, wait for load to remove it to prevent script error window[trans.cb] = function(){ window[trans.cb] = undefined; try{ delete window[trans.cb]; }catch(e){} }; } }, // private handleFailure : function(trans){ this.trans = false; this.destroyTrans(trans, false); if (trans.action === Ext.data.Api.actions.read) { // @deprecated firing loadexception this.fireEvent("loadexception", this, null, trans.arg); } this.fireEvent('exception', this, 'response', trans.action, { response: null, options: trans.arg }); trans.callback.call(trans.scope||window, null, trans.arg, false); }, // inherit docs destroy: function(){ this.abort(); Ext.data.ScriptTagProxy.superclass.destroy.call(this); } });