Can't get jSon dataStore into ExtJS (Sencha Touch) chart: displays error “cannot read property 'length' of undefined”

Question

EDITED I am using Sencha touch charts sample provided for column charts. The code is as below

new Ext.chart.Panel({
    fullscreen: true,
           


        

Answer 1

I solved this issue with the help of a Sencha folk. Thanks Dan. Here is the solution:

1. run the sample on a web server as loading JSON files from the file system can sometimes cause problems.

2. Structure the json data as below

   {
       "data": [
           {
               "School": "Dukes",
               "wins": "3"
           },
           {
               "School": "Emmaus",
               "wins": "10"
           },
           {
               "School": "Maryland",
               "wins": "5"
           },
           {
               "School": "Virginia",
               "wins": "2"
           }
       ]
   }
   

3. Use the below data store

   window.store1 = new Ext.data.Store({
       model: 'Details',
       proxy: {
           type: 'ajax',
           url: 'GetDataset.json',
           reader: {
               root: 'data',
               type: 'json'
           }
       },
       autoLoad: true
   });
   

Answer 2

I'm guessing here, but it seems like a problem I've had before. I believe the problem is with the proxy. Try:

proxy: {
    type: 'rest',
    url: 'http://localhost:2650/AjaxWCFService.svc/GetDataset', 
    reader: {
        root: 'data'
    }

},

Now, you need to define the callback function for the proxy. There's an elegant way with some config, but I honsetly don't know how to do that, so I found out a different solution at the time, the hard way, which is to wrap the JSON which your service returns inside of(like they do here):

Ext.data.JsonP.callback1();

If none of that works, also consider adding the following to your proxy, and emitting a 'total' as part of your JSON response.

totalProperty: 'total'

But keep in mind that I really don't think this will help much at all and that I'm just throwing these ideas out based on a working sample I have.

Try reading this and this. And most of all good luck, that's all of the top of my head mate. Also have a look at this post.

I hope that points you in the right direction. Like I said, I'm not sure, this is my best guess. I'm probably wrong.

Cheers rivanov