title: Populating data in combobox from server in Extjs 4
body: <p>I m getting this error.</p>
  
  <p>Uncaught TypeError: Cannot call method 'indexOf' of undefined .</p>
  
  <pre><code>   var  infost =  Ext.create('Ext.data.JsonStore', {
                      itemId:'infostore',
                      autoLoad:true,
                      fields:['Name','Address','Trade'],
  
                      Proxy:{
                          type:'Ajax',
                          url:'mera.json',
                          actionMethods: {
                                         read: 'POST'
                                     },
                          reader:{    
                              type : 'json',
                              root:'data',
                              totalProperty:'total',
                              record:'stu'
                          }
                      }
  
              });
  </code></pre>