Extjs store load json data,store fields mapping can't show data

 Extjs ext4.2.2.1144

 store fields mapping : 'user.lastName' store.loadData()后数据显示不正确，编辑显示也不正确，用store.loadRawData()可以。
loadData through reader use loadRawData

Ext.onReady(function() {Ext.create('Ext.data.Store', {storeId : 'emptyStore',fields : [],data : []});var grid = Ext.create('Ext.grid.Panel', {title : 'usergrid',tbar : [{text : 'test',handler : function(b, e) {var store = Ext.create('Ext.data.Store', {storeId : 'userStore',fields : [{name : 'user',mapping : 'user.lastName'}, {name : 'address',mapping : 'address.country'}]});var columns = [{text : 'user',dataIndex : 'user',flex : 1,editor : 'textfield'}, {text : 'address',dataIndex : 'address',editor : 'textfield',renderer : function(value, metaData,record, rowIndex, colIndex, store,view) {return value;}}];grid.reconfigure(store, columns);store.loadRawData([{user : {firstName : 'wan',lastName : 'donglei'},address : {country : 'zhongguo',city : 'nanjing'}}]);}}],store : Ext.data.StoreManager.lookup('emptyStore'),columns : [],plugins : [Ext.create('Ext.grid.plugin.CellEditing', {clicksToEdit : 1,listeners : {beforeedit : function(editor, e, eOpts) {var record = e.record;console.log(record.raw.address.city)var value = e.value;if ('-' == value) {return false;} else {return true;}},edit : function(editor, e, eOpts) {var record = e.record;console.log(record.raw.address.city = 'shanghai')}}})],height : 200,width : 300,renderTo : Ext.getBody()});})

参考：

http://docs.sencha.com/extjs/4.0.7/#!/api/Ext.data.Store-method-loadRawData
http://www.sencha.com/forum/showthread.php?192809