app/assets/javascripts/ext/src/data/ScriptTagProxy.js
/*!
* 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.<br>
* <p>
* <b>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.</b><br>
* <p>
* The content passed back from a server resource requested by a ScriptTagProxy <b>must</b> be executable JavaScript
* source code because it is used as the source inside a <script> tag.<br>
* <p>
* 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:
* <p>
* <pre><code>
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(");");
}
</code></pre>
* <p>Below is a PHP example to do the same thing:</p><pre><code>
$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);
}
</code></pre>
* <p>Below is the ASP.Net code to do the same thing:</p><pre><code>
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);
</code></pre>
*
* @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
* <b>Deprecated</b> 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:
* <ul><li><b>The load call timed out.</b> This means the load callback did not execute within the time limit
* specified by {@link #timeout}. In this case, this event will be raised and the
* fourth parameter (read error) will be null.</li>
* <li><b>The load succeeded but the reader could not read the response.</b> This means the server returned
* data, but the configured Reader threw an error while reading the data. In this case, this event will be
* raised and the caught error will be passed along as the fourth parameter of this event.</li></ul>
* 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".<p>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 <tt>read</tt>, 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 <ul>
* <li>The Record block object</li>
* <li>The "arg" argument from the load function</li>
* <li>A boolean success indicator</li>
* </ul>
* @param {Object} scope The scope (<code>this</code> 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);
}
});