Shiny.addCustomMessageHandler("jsondata", function(links) {
    console.log("got new data:", links);
    console.log(links[0]["Source"]);

    //for(i=0;i<links.length;i++) {
    //var allnodes += links[i]["Source"] ;
    //}

  var width = 950, height=1000,color = d3.scale.category20();

  var svg = d3.select("body").append("svg")
                .attr("width", width)
                .attr("height",height);

    var force = d3.layout.force()
                .size([width,height])
                .linkDistance(130)
                .charge(function (d) {return d.weight * - 150});


            var nodesByName = {};

            //console.log(links);
            //console.log(typeof(links));

            //create nodes for each unique source and target in csv
            links.forEach(function(link) {
                    link.source = nodeByName(link.Source);
                    link.target = nodeByName(link.Target);
            });

            //extract array of nodes from map by name
            var nodes = d3.values(nodesByName);

            //create the link lines
            var link = svg.selectAll(".link")
                            .data(links)
                            .enter().append("line")
                            .attr("class", "link");

              // Create the node circles.
            var node = svg.selectAll(".node")
                            .data(nodes)
                            .enter().append("circle")
                            .attr("class", "node")
                            .attr("r", 4.5)
                            .style("fill", function(d) { return color(d.name); })
                            .call(force.drag);



            //node.append("svg:text")
            //  .text(function (d) { return d.source; })
            //  .attr("x", function(d) { return d.x; })
            //  .attr("y", function(d) { return d.y; });

            node.append("text")
                .attr("x",12)
                .attr("dy",".35em")
                .text(function(d) { return d.name; });


            // Start the force layout.
            force.nodes(nodes)
                    .links(links)
                    .on("tick", tick)
                    .start();

            function tick() {
                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; });
              }

            function nodeByName(name) {
                return nodesByName[name] || (nodesByName[name] = {name: name});
              }
});

No Source Target value
1    a       b     3
2    b       c     9
3    a       c     7
4    b       e     4
5    c       d     2