ExtJS Combobox 中Store动态传参数

ExtJS 中有时需要动态传递除了Page信息外的其它参数问题。
1. 依据不同参数load Store；
　　use ：baseParams　和　Store 的 beforeload事件。
2. 解决key事件；

示例代码，注意红色部分：(此处使用了WCF后台处理，WCFJsonReader请参阅博客园小庄)
var readerSupplier = new Ext.data.WCFJsonReader({
root: 'data', id: 'SupplierID', totalProperty: 'totalCount',
fields: [
{ name: 'SupplierID', type: 'int' },
{ name: 'SupplierName', type: 'string' }
]
});

var _strSupplier = '';
var SupplierStore = new Ext.data.Store({
proxy: new Ext.data.WCFHttpProxy({
url: '/Services.svc/GetSuppliersList'
}),
reader: readerSupplier,
remoteSort: true,
baseParams: { limit: 20, nameparam: _strSupplier } //
});
SupplierStore.on("beforeload", function() {
SupplierStore.baseParams = { nameparam: _strSupplier };
});

comboSupplier = new Ext.form.ComboBox({
store: SupplierStore,
displayField: 'SupplierName',
valueField: 'Supplier',
hiddenField: 'Supplier',
mode: 'local',
triggerAction: 'all',
emptyText: 'Type Supplier Code',
selectOnFocus: true,
value: '',
width: 120,
hideTrigger: true,
applyTo: 'ddlSupplier',
　　 pageSize:20,
onKeyUp: function(e) {
_strSupplier = comboSupplier.getRawValue();
if (_strSupplier == "") return;
var k = window.event.keyCode;
if (k != 37 && k != 38 && k != 39 && k != 40 && k != 13) {
var request = { start: 0, limit:20, nameparam: _strSupplier };
SupplierStore.reload({ params: request });
setTimeout('', 500);
}
}
});