Add a computed field on a Model

[vamadou]

Hi,

I have probably overlooked this one but I can't find how to add a "computed" field on a store via the Designer. By computed I mean the 'fullname' field in the example below:

Ext.define('app.model.User', {
    extend: 'Ext.data.Model',
    config: {
        fields: ['firstName', 'middleName', 'lastName']
    },

    fullName: function() {
        var d = this.data,
        names = [
            d.firstName,
            d.middleName,
            d.lastName
        ];
        return names.join(" ");
    }
});

Could you help me ?
Thanks a lot
Regards

Vincent