extjs Таблицы, модели, маппинг

[
{"WorckGroup":"3D",
    "Statistics":[
    {"Specialist":"В А","SCallCount":64,"AverageDuration":0.1136067},
    {"Specialist":"К Т","SCallCount":170,"AverageDuration":0.1045816}]
{"WorckGroup":"SD",
    "Statistics":[
    {"Specialist":"B A","SCallCount":197,"AverageDuration":0.1364689}]
}
]

StatisticsFlatJsonReader = Ext.extend(Ext.data.JsonReader, {
    readRecords: function(data) {        
        var arraysOfRecords = Ext.Array.map(data, function (groupRecord) {
            var group = groupRecord['WorckGroup'];
            var rawRecords = groupRecord['Statistics'];
            Ext.Array.each(rawRecords, function (rawRecord) {
                rawRecord['WorckGroup'] = group;
            });
            return rawRecords;
        });                
        return StatisticsFlatJsonReader.superclass.readRecords.call(this, Ext.Array.merge(arraysOfRecords));
    }
 
});
Ext.data.ReaderMgr.registerType('statisticsflatjson', StatisticsFlatJsonReader);

Ext.define('myModel', {
    extend: 'Ext.data.Model',
    fields: [
        { name: 'WorckGroup', type: 'string' },        
        { name: 'Specialist', type: 'string' },
        { name: 'ScallCount', type: 'int' },
        { name: 'AverageDuration', type: 'float' }
    ]
});


var store = Ext.create('Ext.data.Store', {
    model: 'myModel',
    proxy: {
        type: 'ajax',
        url: '/omnireports/ajaxgrid',
        reader: {
            type: 'statisticsflatjson'
        }
    },
    autoLoad: true
});


var basegrid = Ext.create('Ext.grid.Panel', {
    store: store,
    columns: [
    { header: 'Рабочая группа', width: 200, dataIndex: 'WorckGroup' },
    { header: 'Специалист', dataIndex: 'Specialist' },
    { header: 'Количество обращений', dataIndex: 'ScallCount' },
    { header: 'Среднее время решения', dataindex: 'AverageDuration' }
    ],
});

[{"WorkGroup":"Группа поддержки 3D",
        "Statistic":[
            {"Specialist":"Александр Константинович",
            "SCallCount":64,"AverageDuration":0.1136067,"leaf":true},
            {"Specialist":"Татьяна Алексеевна",
            "SCallCount":172,"AverageDuration":0.1058641,"leaf":true},
            {"Specialist":"Алексей Валентинович",
            "SCallCount":72,"AverageDuration":0.4269940,"leaf":true}]},
    {"WorkGroup":"Группа поддержки сервиса КСУП",
        "Statistic":[
            {"Specialist":"Руслан Евгеньевич",
            "SCallCount":67,"AverageDuration":0.1090698,"leaf":true},
            {"Specialist":"Алексей Алексеевич",
            "SCallCount":17,"AverageDuration":0.1125816,"leaf":true},
            {"Specialist":"Анна Владимировна",
            "SCallCount":172,"AverageDuration":0.0632347,"leaf":true},
            {"Specialist":"Мирослав Александрович",
            "SCallCount":315,"AverageDuration":0.0945766,"leaf":true},
            {"Specialist":"Николай Владимирович",
            "SCallCount":7,"AverageDuration":0.2342261,"leaf":true}]},
        ]}

Ext.define('WorkGroupModel', {
   extend: 'Ext.data.Model',
    proxy: {
       type: 'rest',
       url: '/omnireports/ajaxgrid',
       reader: {
          type: 'json'
       }
     },
     fields: [{ name: 'text', mapping: 'WorkGroup' }],
     hasMany: { name: 'children', model: 'StatisticModel', associationKey: 'Statistic' }
})

Ext.define('StatisticModel', {
  extend: 'Ext.data.Model',
    fields: [
      { name: 'text', mapping: 'Specialist' },
      'SCallCount','AverageDuration',
      { name: 'leaf', defaultVale: true }
    ]
})

WorkGroupModel.load(1, {
  success: function (wg) {
    console.log("WorkGroup: " + wg.get('text'));
      wg.children().each(function (specialist) {
        console.log("Specialist: " + specialist.get('text') + "\n leaf: " + specialist.get('leaf'));
      });
  }
});

/////////
WorkGroup: Группа поддержки 3D
Specialist: Александр Константинович
 leaf: true
Specialist: Татьяна Алексеевна
 leaf: true
Specialist: Алексей Валентинович
 leaf: true

Ext.define('basegrid', {
    extend: 'Ext.tree.Panel',
    xtype: 'tree-grid',
    title: 'Core Team Projects',
    height: 300,
    useArrows: true,
    rootVisible: false,
    multiSelect: true,
    singleExpand: false,
    initComponent: function () {
        this.width = 500;
        Ext.apply(this, {
            store: new Ext.data.TreeStore({
                model: WorkGroupModel,
                proxy: {
                    type: 'rest',
                    url: '/omnireports/ajaxgrid',
                    reader: {
                        type: 'json'
                    }
                },
                    autoLoad: true,
                    folderSort: true
                }),
            columns: [{
                xtype: 'treecolumn',
                text: 'Task',
                flex: 2,
                sortable: true,
                dataIndex: 'text'
            }]
        });
        this.callParent();
    }
});