排序列表Sencha Touch

Question

I have used the example code from "Intro to List Components". I was able to successfully run it on a android simulator. Now I want to sort it by firstName rather the lastName. When I changed to sorters: "lastName" to firstName, I can see that the Index bar is not in alphabetical order. How can I sort by firstName with proper index order?

Ext.regModel('Contact', {
fields: ['firstName', 'lastName']
});

ListDemo.ListStore = new Ext.data.Store({
model: 'Contact',
sorters: 'firstName',

getGroupString : function(record) {
    return record.get('lastName')[0];
},
data: [
    { firstName: "Domino",      lastName: "Derval" },
    { firstName: "Elektra",     lastName: "King" },
    { firstName: "Fiona",       lastName: "Volpe" },
    { firstName: "Holly",       lastName: "Goodhead" },


]
});

Answer 1

change this line:

          getGroupString : function(record) {
               return record.get('lastName')[0];
           },

to:

           getGroupString : function(record) {
                  return record.get('firstName')[0];
       },