表单下拉查询树

//用到延迟函数，需引入js
<script src="../../../../Content/Scripts/Tool.js" type="text/javascript"></script>
<ext:Hidden runat="server" ID="CustUnitID"></ext:Hidden>
<ext:DropDownField runat="server" ID="CustUnitName" FieldLabel="客户单位" LabelAlign="Right" LabelWidth="60"
    Flex="1" Editable="false" MarginSpec="0 20 0 0">
    <Triggers>
        <ext:FieldTrigger Icon="Clear" Tag="Clear"></ext:FieldTrigger>
    </Triggers>
    <Listeners>
        <TriggerClick Handler="item.reset()" />
        <Expand Handler="item.component.store.load()"></Expand>
    </Listeners>
    <Component>
        <ext:TreePanel ID="QueryCustUnit" runat="server" Height="250" Scrollable="true" Animate="true" ContainerScroll="true"
            RootVisible="false" HideHeaders="true">
            <TopBar>
                <ext:Toolbar runat="server">
                    <Items>
                        <ext:TriggerField runat="server" ID="QueryCustUnitKey" Flex="1" EmptyText="请输入查询内容">
                            <Triggers>
                                <ext:FieldTrigger Icon="Clear" Tag="Clear"></ext:FieldTrigger>
                            </Triggers>
                            <Listeners>
                                <TriggerClick Handler="item.reset()" />
                                <Change Handler="CrateStartDelayedTask(App.QueryCustUnit.store.load,500,App.QueryCustUnit.store)"></Change>
                            </Listeners>
                        </ext:TriggerField>
                    </Items>
                </ext:Toolbar>
            </TopBar>
            <Root>
                <ext:Node Expanded="true">
                </ext:Node>
            </Root>
            <Store>
                <ext:TreeStore runat="server" PageSize="20" AutoLoad="false">
                    <Model>
                        <ext:Model runat="server">
                            <Fields>
                                <ext:ModelField Name="OrgUseDataID" />
                                <ext:ModelField Name="OrgUseDataName" />
                            </Fields>
                        </ext:Model>
                    </Model>
                    <Proxy>
                        <ext:AjaxProxy Url="/SY_WMBCP/OrgUseData/GetOrgCustUseData">
                            <ActionMethods Read="post" />
                            <Reader>
                                <ext:JsonReader Root="Data" />
                            </Reader>
                        </ext:AjaxProxy>
                    </Proxy>
                    <Parameters>
                        <ext:StoreParameter Name="key" Mode="Raw" Value="App.QueryCustUnitKey&&App.QueryCustUnitKey.getValue()" />
                    </Parameters>
                </ext:TreeStore>
            </Store>
            <ColumnModel>
                <Columns>
                    <ext:TreeColumn runat="server" DataIndex="OrgUseDataName" Flex="1"></ext:TreeColumn>
                </Columns>
            </ColumnModel>
            <Listeners>
                <ItemClick Handler="App.CustUnitID.setValue(record.data.OrgUseDataID);App.CustUnitName.setValue(record.data.OrgUseDataName);">
                </ItemClick>
            </Listeners>
        </ext:TreePanel>
    </Component>
</ext:DropDownField>