Custom JsonStore and Template Implementation ExtJs

I have a DataView which displays a list of images loaded from a JsonStore. However, the label required for each image is not an available attribute within the JsonStore - in other words, for each record in the store, I need to fetch (via an AJAX request) the label from another service.

Is is possible to call a custom function to grab the label before each image is displayed from the JsonStore?

Here's my current implementation:

var view = new Ext.DataView({
     store: new Ext.data.JsonStore({
        autoLoad:false,
        root: 'root',
        id:'ID',
        fields:['ID']
    }),
    tpl: new Ext.XTemplate(
        '<tpl for=".">',
        '<div class="wrapper" id="{ID}">',
        '<div class="thumb"><a href="'+ URL +'{ID}" title="{*label here*}">',
        '&开发者_StackOverflow中文版lt;img src="'+ THUMB_URL +'{ID}"></a></div>',
        '<span>{*label here*}</span></div>',
        '</tpl>'
        )
});

Thanks!

---

Apologies for answering my own question, but it looks as if prepareData does exactly what I want - allowing me to act on each individual record in the store before it's sent out for formatting.