extjs - change url of xmlTreeLoader and reload?

I'm using extJs and I got a xmlTreeLoader:

filterTreeLoader = new Ext.app.BookLoader({
    dataUrl:'sampledata/xml-tree-data.xml'
})

Now I want to change the dataUrl ar runtime and reload the tree. I can change the dataUrl, but how do I make a refresh? Can't see a proper method on the extJs api...

        Ext.getCmp('tfProcChainDesc').setValue('TESvfdT');
    // Change the dataUrl
    filterTreeLoader.dataUrl = 'sampledata/xml-tree-data.xml';
    // How to refresh here?

PS: BookLoader extends TreeLoader开发者_如何学运维, so I searched this api... Thanks guys!

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Have you tried calling TreeLoader.load()?