Rails and Coffee to render an object graph for any rails model

ApplicationController.rb

#As coded this is suiteable for adding to ApplicationController, or an included controller module
#It would also be cool to refactor this code to be added to fat models instead
def object_graph
  @prune_nodes = params[:prune_nodes] #When the crawler hits a node of this class, it will stop
  model_name = controller_name.classify
  root_object = model_name.classify.constantize.find(params[:id])
  edge_list = {} #This is implemented as an object instead of an array for lookup performance reasons
  nodes = {}
  object_ident = ->(object){"#{object.id}-#{object.class}"} #helper function
  fill_object_data = ->(object, ident) do #add some data to the JSON object that will be used by the renderer
    edge_list[ident] = [] if !edge_list[ident] #initialize if needed
    unless nodes[ident]
      nodes[ident] = {
    id:object.id,
          type:object.class.to_s,
          href:(url_for(object) rescue nil), #if there are no routes for this object leave it blank
          name:ident,
          description: (object.web_description rescue "") #if you add #web_description to the models it will be used here
        }
    end
  end
  traverse = ->(object) do #DFS over the model object graph by reflecting on associations
    object.class.reflect_on_all_associations.each do |assoc|
      this_object_ident = object_ident.call object
      fill_object_data.call object, this_object_ident
      associated_objects = Array.wrap object.send(assoc.name) #Call the association on the object i.e. `foo.bars`
      associated_objects.each do |assoc_obj|
        assoc_obj_ident = object_ident.call assoc_obj
        edge_list[this_object_ident].push assoc_obj_ident
        next if edge_list[assoc_obj_ident] #if we've already seen it, skip it
        unless @prune_nodes.include? assoc_obj.class.to_s.underscore #if it's on the prune list, add it, but don't recurse
          traverse.call(assoc_obj)
        else
          fill_object_data.call assoc_obj, assoc_obj_ident
        end
      end
    end
  end
  traverse.call(root_object)

  @json = {rootId:object_ident.call(root_object), edges:edge_list, nodes:nodes}.to_json
  render '/application/object_graph' #keep the view in a common folder

end

object_graph.coffee

#using the [VivaGraph library](https://github.com/anvaka/VivaGraphJS) to build a nice looking graph
#this examples requires Underscore.js and the jQuery-ui theme roller icons
ObjectGraph = (rootId, nodes, nodeLinks)->
  graph = Viva.Graph.graph()

  _.each nodes, (node, node_id)->
    graph.addNode node_id, node

  _.each nodeLinks, (nodeLinkList, key)->
    _.each nodeLinkList, (nodeLink)->
      graph.addLink(key, nodeLink)

  graphics = Viva.Graph.View.svgGraphics()
  graphics.node (node)-> #build the node element from SVG and HTML components
    fillColor = if node.data.name == rootId then 'red' else 'blue'
    svg = Viva.Graph.svg('svg')
    g = svg.appendChild Viva.Graph.svg('g')
    g.appendChild Viva.Graph.svg('rect').attr('width', 10).attr('height', 10).attr('fill', fillColor)

    #foreign element sizeing could be done a lot better than what I have here
    foreignOject = g.appendChild Viva.Graph.svg('foreignObject').attr('width', '13em').attr('height', '2em').attr('fill', fillColor)
    body = foreignOject.appendChild document.createElementNS('http://www.w3.org/1999/xhtml', 'body')
    div = body.appendChild document.createElement('div')
    div.appendChild(document.createElement 'span' ).textContent = node.data.type
    div2 = body.appendChild document.createElement('div')
    div2.appendChild(document.createElement 'span').textContent = node.data.description
    if node.data.href
        a = div.appendChild document.createElement('a')
        a.setAttribute('href', node.data.href)
        linkIcon = a.appendChild document.createElement('span')
        linkIcon.setAttribute('class', "ui-icon ui-icon-link")
        linkIcon.setAttribute('style', "display:inline-block") #so icon and text are on the same line, using the style sheet didn't work for me
    svg

  renderer = Viva.Graph.View.renderer graph, {graphics:graphics, container:document.getElementById('your_ele_id')}
  renderer.run()

object_graph.html.erb

<% if @prune_nodes %>
<ul class='inline'>
  <li>Network Pruned Nodes:</li>
  <% @prune_nodes.each do |prune|%>
    <li><%= raw prune.titleize %> </li>
  <% end %>
</ul>
<% end %>

<script type="text/javascript">
    json = <%= raw @json %>
    ObjectGraph(json.rootId, json.nodes, json.edges);
</script>

<style type="text/css">
    svg{ overflow:visible !important; } /*easier than trying to size the SVG element right*/
</style>