Class Ext.data.Field

// example of convert function
function fullName(v, record){
    return record.name.last + ', ' + record.name.first;
}

function location(v, record){
    return !record.city ? '' : (record.city + ', ' + record.state);
}

var Dude = Ext.data.Record.create([
    {name: 'fullname',  convert: fullName},
    {name: 'firstname', mapping: 'name.first'},
    {name: 'lastname',  mapping: 'name.last'},
    {name: 'city', defaultValue: 'homeless'},
    'state',
    {name: 'location',  convert: location}
]);

// create the data store
var store = new Ext.data.Store({
    reader: new Ext.data.JsonReader(
        {
            idProperty: 'key',
            root: 'daRoot',
            totalProperty: 'total'
        },
        Dude  // recordType
    )
});

var myData = [
    { key: 1,
      name: { first: 'Fat',    last:  'Albert' }
      // notice no city, state provided in data object
    },
    { key: 2,
      name: { first: 'Barney', last:  'Rubble' },
      city: 'Bedrock', state: 'Stoneridge'
    },
    { key: 3,
      name: { first: 'Cliff',  last:  'Claven' },
      city: 'Boston',  state: 'MA'
    }
];

(Optional) Used when converting received data into a Date when the type is specified as "date".

A format string for the Date.parseDate function, or "timestamp" if the value provided by the Reader is a UNIX timestamp, or "time" if the value provided by the Reader is a javascript millisecond timestamp. See Date

(Optional) A path expression for use by the Ext.data.DataReader implementation that is creating the Record to extract the Field value from the data object. If the path expression is the same as the field name, the mapping may be omitted.

The form of the mapping expression depends on the Reader being used.

If a more complex value extraction strategy is required, then configure the Field with a convert function. This is passed the whole row object, and may interrogate it in whatever way is necessary in order to return the desired data.

Note: In the simplest case, if no properties other than name are required, a field definition may consist of just a String for the field name.

// current sort     after sort we want
// +-+------+          +-+------+
// |1|First |          |1|First |
// |2|Last  |          |3|Second|
// |3|Second|          |2|Last  |
// +-+------+          +-+------+

sortType: function(value) {
   switch (value.toLowerCase()) // native toLowerCase():
   {
      case 'first': return 1;
      case 'second': return 2;
      default: return 3;
   }
}

This may also be specified by referencing a member of the Ext.data.Types class.

Developers may create their own application-specific data types by defining new members of the Ext.data.Types class.

(Optional) Use when converting received data into a Number type (either int or float). If the value cannot be parsed, null will be used if useNull is true, otherwise the value will be 0. Defaults to false