Ext Js Tree
Jack Slocum and the guys over at Ext JS labs have delivered in my humble opinion one of the best JavaScript UI libs I have ever had the pleasure to work with.
They have a particularly nice tree widget that I’ve leveraged a few times using Json rendered from rails. This page is the only one I’ve found that explains how to populate it from rails and it leverages acts_as_nested_set. I found that to be a bit of overkill (and in Japanese or something) so I did an alternate version which uses acts_as_tree instead.
Here’s hoping this saves someone some time… Enjoy 
In your Model:
acts_as_tree
In your controller:
def get_tree_data
folders = Folder.find(:all)
data = get_tree(folders)
render :text=>data.to_json, :layout=>false
end
In your application controller:
def get_node(obj)
if obj.children.empty?
return [{"text"=>obj.name,"id"=>"#{obj.class}_#{obj.id}","cls"=>"#{obj.class}_node".downcase,"leaf"=>true}]
else
return [{"text"=>obj.name,"id"=>"#{obj.class}_#{obj.id}","cls"=>"#{obj.class}_node".downcase,"leaf"=>false}]
end
end
def get_tree(collection)
data = Array.new
collection.each { |item|
if data.empty?
data = get_node(item)
else
data.concat(get_node(item))
end
}
return data
end
