I want to display the output of a JSON file as a d3.js graph, but I'm having trouble accessing the JSON data in my controller. Here is the relevant code:
First, let's take a look at the model:
class User < ActiveRecord::Base
has_many :relationships
end
class User
def self.including_relationships
User.joins("INNER JOIN relationships ON users.id = relationships.user_id").select("users.name, relationships.user_id, relationships.followsid,users.value").each_with_object(Hash.new{|h, k| h[k] = []}) do |a, obj|
obj['nodes'] << a.slice('name')
obj['links'] << a.slice('user_id', 'followsid', 'value')
end
end
end
And here is the controller:
class UserController < ApplicationController
def index
render :json => User.including_relationships
end
end
Finally, we have the index.html page:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Graph Display</title>
<link href="stylesheets/style.css" rel="stylesheet" type="text/css" media="screen" />
<script src="http://d3js.org/d3.v3.min.js"></script>
</head>
<body>
<script>
var width = 960,
height = 500;
var color = d3.scale.category20();
var force = d3.layout.force()
.charge(-120)
.linkDistance(30)
.size([width, height]);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
// Make an AJAX call to fetch the JSON data from the controller
d3.json("user.json", function(error, graph) {
force
.nodes(graph.nodes)
.links(graph.links)
.start();
var link = svg.selectAll(".link")
.data(graph.links)
.enter().append("line")
.attr("class", "link")
.style("stroke-width", function(d) { return Math.sqrt(d.value); });
var node = svg.selectAll(".node")
.data(graph.nodes)
.enter().append("circle")
.attr("class", "node")
.attr("r", 5)
.style("fill", function(d) { return color(d.group); })
.call(force.drag);
node.append("title")
.text(function(d) { return d.name; });
force.on("tick", function() {
link.attr("x1", function(d) { return d.source.x; })
.attr("y1", function(d) { return d.source.y; })
.attr("x2", function(d) { return d.target.x; })
.attr("y2", function(d) { return d.target.y; });
node.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; });
});
});
</script>
</body>
</html>
It seems that the issue lies with the line:
d3.json("user.json", function(error, graph) {
I need to change the reference to my JSON file, but I'm not sure how. Any suggestions would be appreciated.
Update
I have tried using AJAX to fetch the JSON data from the controller as suggested here:
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Graph Display</title>
<link href="stylesheets/style.css" rel="stylesheet" type="text/css" media="screen" />
<script src="example.js"></script>
</head>
<body>
<script>
$.ajax({
type: 'GET',
url: 'localhost:3000/user',
success: function(data) {
var userJSON = data;
}
})
var width = 960,
height = 500;
var color = d3.scale.category20();
var force = d3.layout.force()
.charge(-120)
.linkDistance(30)
.size([width, height]);
var svg = d3.select("body").append("svg")
.attr("width", width)
.attr("height", height);
d3.json(userJSON, function(error, graph) {
force
.nodes(graph.nodes)
.links(graph.links)
.start();
var link = svg.selectAll(".link")
.data(graph.links)
.enter().append("line")
.attr("class", "link")
.style("stroke-width", function(d) { return Math.sqrt(d.value); });
var node = svg.selectAll(".node")
.data(graph.nodes)
.enter().append("circle")
.attr("class", "node")
.attr("r", 5)
.style("fill", function(d) { return color(d.group); })
.call(force.drag);
node.append("title")
.text(function(d) { return d.name; });
force.on("tick", function() {
link.attr("x1", function(d) { return d.source.x; })
.attr("y1", function(d) { return d.source.y; })
.attr("x2", function(d) { return d.target.x; })
.attr("y2", function(d) { return d.target.y; });
node.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; });
});
});
</script>
</body>
</html>
However, when I try this, all I see is the JSON result, and it doesn't get included in index.html.erb. I'm not sure why. Any advice would be greatly appreciated.