How to Display Nested Json data in EXTJS 4 Grids?

Question

I am working on ExtJS 4.0 and I want to display nested JSON data in a grid. For this I use the example given in Ext.data.reader.Reader docs, "Loading Nested Data". It is good and simple but now I want to display this data in a grid. How do I set dataIndex?

This is my sample model and store:

Ext.define("data", {
    extend: 'Ext.data.Model',
    fields: ['year', 'state'],
    hasMany: {
        model: 'record',
        name: 'record'
    },
    proxy: {
        type: 'rest',
        url: 'Column.json.php',
        reader: {
            type: 'json',
            root: 'data'
        }
    }
});

Ext.define("record", {
    extend: 'Ext.data.Model',
    fields: ['id', 'autorization', 'expendture'],
    belongsTo: 'User'
});
var store1 = new Ext.data.Store({
    model: "data"
});

And my JSON:

{
    "data": [{
        "year": "2010",
        "state": "MP",
        "record": [{
            "id": "auth",
            "autorization": "9.201"
        }, {
            "id": "exp",
            "expendture": "1.250"
        }]
    }]
}

I want to read autorization and expendture with id

Answer 1

You have to do it at the Model/Record level using the mapping confg in fields, so you'd do something like this:

Ext.define("record", {
    extend: 'Ext.data.Model',
    fields: [
        'id',
        {name: 'autorization', mapping: 'record[0].autorization'},
        {name: 'expendture', mapping: 'record[1].expendture'}
    ],
    belongsTo: 'User'
});

It's good to note that it is probably quicker to ask questions over on the Sencha Forums.

Answer 2

I want to point out that Store.loadData does not respect the field mapping

The issue is that the Sencha team changed loadData's behavior, AND it's not something that's documented in a way that is clear. So if you are using it, add the following to your code base (above your app code, but below ext-all.js):

Ext.override(Ext.data.Store, {
loadDataViaReader : function(data, append) {
var me      = this,
    result  = me.proxy.reader.read(data),
    records = result.records;

me.loadRecords(records, { addRecords: append });
me.fireEvent('load', me, result.records, true);
}            
 });

then use:

mystore.loadDataViaReader(data)