How to debug loading of store

**mobitinker** · 30 Jul 2011, 2:23 PM

Hi,

I've gotten stuck on loading a store and am wondering how to debug the problem. If someone can see my mistake I'd be most grateful.

My app is trying to load a list from Google's RSS feed widget. I'm using the scripttag pattern to load the list's store. Things seem to flow as expected, but the store does not get loaded.

I can see the scripttag request being returned from the server with the expected data. The Chrome debugger reports trouble as:

Uncaught TypeError: Cannot read property 'length' of undefined. Tracing the stack I see this is coming from this line in sencha-touch-debug-w-comments.js:

at Ext.data.Reader.Ext.extend.read which is seeing the response value of '0' at
result = reader.read(response)

Watching traffic with Fiddler I see in JSON view this, which looks as expected:

The raw text coming from the server starts like this:

stcCallback1001('0', {"feed":{"feedUrl":"http://www.mercycorps.org/blog/feed","title":"Mercy Corps blogs","link":"http://www.mercycorps.org/blog.html","author":"","description":"","type":"rss20","entries":[{"title":"Horror in the Horn of Africa: reflections and projections","link":"http://www.mercycorps.org/danoneill/blog/25255","author":"Dan O\u0026#39;Neill","publishedDate":"Tue, 02 Aug 2011 09:01:45 -0700","contentSnippet":"\n\t\n\tSudan, 1984. Photo: Jon Warren for Mercy Corps\t\nI first encountered extreme poverty and hunger in 1972 when I drove through ...","content":"\u003cdiv style\u003d\"width:590px\"\u003e\n\t\u003ca href\u003d

The code looks like this:

Code:

<!DOCTYPE HTML">
<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
        <title>Scaffold</title>

        <link href="lib/touch/resources/css/sencha-touch.css" rel="stylesheet" type="text/css" />
		<script src="http://www.google.com/jsapi" type="text/javascript"></script>
        <script type="text/javascript" src="lib/touch/sencha-touch.js"></script>
	
        <script type="text/javascript">
			
			//Initialize Google
			google.load('feeds', '1');
	        
			google.setOnLoadCallback(initialize);
			
			function initialize() {
				console.log('init');
			}
			
			Ext.setup({
			    onReady : function() {
					console.log('onReady');
			    	Ext.regModel('Article', {
			        	fields: [
			    	         	{name: 'title', type: 'string' },
			    	         	{name: 'link', type: 'string'}
			        	         ]
			        });

			    	/*
			    	Ext.regModel('Contact', {
			            fields: ['title', 'link']
			        });
					*/
					
			        var myFeed = {
			            itemTpl: '<div class="contact2"><strong>{title}</strong> {link}</div>',

			        	store : new Ext.data.Store({
			                model  : 'Article',
			                proxy : {
			                	type: 'scripttag',
			                	url: 'http://www.google.com/uds/Gfeeds',
			                	extraParams: {
			    	                context: '0',
			    	                num: '10',
			    	                hl: 'en',
			    	                output: 'json',
			    	                q: 'http://www.mercycorps.org/blog/feed',
			    	                v: '1.0',
			    	                nocache: '0',
			    	                //filters: []
			                    },
			                    reader: {
			                    	type: 'json',
			                    	root: 'feed.entries'
			                    }
			                },
			        		autoLoad: true,
			        		
			        		listeners : {
			        			load: function(s, records, success){
			        				//Not reached
			        				console.log('Loaded!')
			        			},
			                	beforeload: function(s, operation) {
			                		//This fires ok
			                		console.log('before load');
			                	}
			        		}
			        		
			            })

			        };


		            new Ext.List(Ext.apply(myFeed, {
		                floating: true,
		                width: 350,
		                height: 370,
		                centered: true,
		                modal: true,
		                hideOnMaskTap: false
		            })).show();
			    }
			});

        </script>
 
    </head>

    <body>
    </body>
</html>

**mobitinker** · 3 Aug 2011, 6:59 AM

Hi again,

I hadn't seen a reply on this and thought it might be because my post was not clear enough. I updated it to include more detail. If anyone has an idea I'd really appreciate it.

Thanks!

**samsonasu** · 3 Aug 2011, 9:29 AM

I don't know how that script tag proxy works, but it seems to be some kind of jsonp callback. From your raw data, google is coming back with callback('0', {json: here}); I have a feeling your reader is getting the first argument ('0') instead of the second.

Sorry I don't know how to fix it, but I'm pretty sure that's the problem. Good luck

**mobitinker** · 3 Aug 2011, 6:12 PM

Awesome. Thanks for the pointer. The problem was that I was specifying a 'context' of '0' which was being sent back at the front of the response as you pointed out. When I removed that extraParam, the raw data was returned as follows. I adjusted the root for the proxy to be 'responseData.feed.entries' and all was good. Thanks!!

stcCallback1002({"responseData": {"feed":{"feedUrl":"http://www.mercycorps.org/blog/feed","title":"Mercy Corps blogs","link":"http://www.mercycorps.org/blog.html","author":"","description":"","type":"rss20","entries":[{"title":"Update: Providing clean water to 16 drought-affected Kenyan villages","link":"http://www.mercycorps.org/rogerburks/blog/25315","author":"Roger Burks","publishedDate":"Wed, 03 Aug

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