Create a store from a subset of the JSON Store

I have a JSON store defined as follows

var subAccountStore = new Ext.data.JsonStore({
  autoLoad: true,
  proxy: {
    type:'ajax',
    url : '/opUI/json/subaccount.action?name="ABC"'
  },
  fields: ['accountName', 'quantity','accountNumbers'],
  listeners: {
    load: function(store, records, success) {
      // ???????
    },
    single: true
  }
});

      

        
        
        
      

    

and sample data

[{"accountName":"'ABC'","quantity":100,"accountNumbers":['12345A','12345B','12345C']},{"accountName":"'XYZ'","quantity":100,"accountNumbers":['99999A','99999B','99999C']}]

      

        
        
        
      

    

How do I create dynamic storage for accountNumbers

and assign a combo box inside a grid?

Thanks Tharahan