D3 Graph Example Using In Memory Object - ruby-on-rails-3

Question

This seems like it should be simple, but I have spent literally hours without any success.
Take the D3 graph example at http://bl.ocks.org/mbostock/950642. The example uses a local file called graph.json. I have set up a Rails app to serve a similar graph, however I don't want to write a file of the JSON. Rather, I generate the nodes and links into an object such as:
{"nodes":[{"node_type":"Person","name":"Damien","id":"damien_person"}, {"node_type":"Person","name":"Grant","id":"grant_person"}}],
"links":[{"source":"damien_person","target":"grant_person","label":"Friends"}}
Now when I render the D3, I need to update the call d3.json("graph.json", function(json) {...}); to reference my in-memory object rather than the local file (or url). However, everything I've tried breaks my html/javascript. For example I tried setting the var dataset = <%= raw(#myInMemoryObject) %>;, and that works for assignment (I did an alert on the dataset), however I can't get the D3 code to use it.
How can I replace the d3.json call in order to use my in-memory object?
Thank you,
Damien

Answer 1

Your idea of using, for example, var dataset = <%= raw(#myInMemoryObject) %>; is the right way to go but you need to prep your object to be in the right format.
The nodes specified in the links need to either be numeric references to nodes in the nodes array eg. 0 for first, 1 for second
var json ={
"nodes":[{"name":"Damien","id":"a"}, {"name":"Bob","id":"b"}],
"links":[{"source":0, "target":1,"value":1}]
}
or links to the actual objects which make the nodes themselves:
var a = {"name":"Damien","id":"a"};
var b = {"name":"Bob","id":"b"}
var json ={
"nodes":[a,b],
"links":[{"source":a,"target":b,"value":1}]
};
Relevant discussion is here: https://groups.google.com/forum/?fromgroups=#!topic/d3-js/LWuhBeEipz4
Example here: http://jsfiddle.net/5A9eV/1/