Reading json values after loading to a store - extjs4

Question

I am trying to read the values from json which is returned from the db. But I am unable to do that. Its giving undefined.
In Firebug its giving the correct values in the following format
{ "COLUMNS":["B","C","D","E","F","G"],
"DATA":[[1.253,0.54,2.54,8.245,0,0.253]]
}
When I give console.log(response[0].DATA.B), its giving undefined.
I tried alert(response[0].get('B')); This is also giving undefined.
alert(success) is giving true.
Can someone please tell me what is going wrong here.
Thanks in advance..
Here is the code I am using
Ext.define('DBRec', {
extend: 'Ext.data.Model',
fields: [
{name:'A', type :'string'},
{name:'B', type:'string'},
{name:'C', type:'string'},
{name:'D', type:'string'},
{name:'E', type:'string'},
{name:'F', type:'string'},
{name:'G', type:'string'}
]
});
var DBRecStore=Ext.create('Ext.data.Store', {
model: 'DBRec',
proxy: {
type: 'ajax',
url : 'dbFunctions.cfc?method=getRec',
reader: {
type:'json',
root:'DATA',
fields: ['B', 'C', 'D', 'E', 'F', 'G']
}
}
});
function loadLimits()
{
DBRecStore.load({
params: {
reader: 'json',
returnFormat: 'JSON'
},
callback: function(response, options, success){
alert(DBRecStore.getCount());
if (DBRecStore.getCount() == '0') {
alert("no records found");
}
else
{
alert("records found");
console.log(response[0].DATA.B+" "+response[0].DATA.C);
}
}
});
}

Answer 1

If you not using your own reader, as i see you don't, then your data array must be a objects array, not array of arrays.
{ "DATA":[{a:1.253,b: 0.54,c: 2.54,d:8.245,e:0,0.253}] }
And you don't need to define field in store, it's already in model.