Change styling of dojo treegrid cell if value changes

Question

What I have is a treegrid populated with values from ajax. Every 30 seconds the store is refreshed and new data is displayed.

I need to change the styling (color or background-color) of a treegrid cell when it's value differs from the old one. The requirement is to make the comparison and styling from javascript.

Any ideas on how this could be done ?

Answer 1

You could use dijit.Tree's getRowStyle method to modify the style dynamically. It will be called whenever a row needs to be rendered.

Something like this might get you started:

(function(){ // closure for private variables

var previousValues = {};

var myTree = ... // lookup dijit.Tree via dijit.byId, or create

myTree.getRowStyle = function(item){
    var style = {};
    var itemId = myTree.store.getIdentity(item);
    var newValue = myTree.store.getValue(item, "MY_ITEM_VALUE");
    if(newValue !== null &&
            previousValues[itemId] !== null &&
            previousValues[itemId] !== newValue) {
        style.backgroundColor = "#0000FF";
        previousValues[itemId] = newValue;
    }
    return style;
};

})();

There may be better ways to keep track of the previous values, but since your store is getting changed, I really can't think of one.