Error: <path> attribute d: Expected number, "MNaN,25.707269548…

Question

Before posting, I looked at this SO question that had the same issue, and I'm sure the solution is similar to his, but I'm new to d3 so I have no idea how to fix mine.

I'm trying to modify a d3 chart so that it reads from a json stream instead of the csv file. The graph is based on this bl.ocks.org link.

So I essentially created a WCF service that returns exactly the same data as the data in the CSV. The stream returned looks like this:

[
    {"date":"6/1/2017","sales":1394.46},
    {"date":"6/2/2017","sales":1366.42},
    {"date":"6/3/2017","sales":1498.58}
]

My d3 chart that looks like this:

//d3.csv("sp500.csv", type, function(error, data) {
d3.json("http://MyServer:86/Erase.svc/GetDataErase", function(error, data) {
  console.log(data);
  if (error) throw error;

  x.domain(d3.extent(data, function(d) { return d.date; }));
  y.domain([0, d3.max(data, function(d) { return d.sales; })]);
  x2.domain(x.domain());
  y2.domain(y.domain());

  focus.append("path")
      .datum(data)
      .attr("class", "area")
      .attr("d", area);

  focus.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis);

  focus.append("g")
      .attr("class", "axis axis--y")
      .call(yAxis);

  context.append("path")
      .datum(data)
      .attr("class", "area")
      .attr("d", area2);

  context.append("g")
      .attr("class", "axis axis--x")
      .attr("transform", "translate(0," + height2 + ")")
      .call(xAxis2);

  context.append("g")
      .attr("class", "brush")
      .call(brush)
      .call(brush.move, x.range());

  svg.append("rect")
      .attr("class", "zoom")
      .attr("width", width)
      .attr("height", height)
      .attr("transform", "translate(" + margin.left + "," + margin.top + ")")
      .call(zoom);
});

This csv file looks like this:

date,sales
6/1/2017,1394.46
6/2/2017,1366.42

console.log(data); returns the array correctly, so the wcf service is not the problem.

Any help is appreciated.

Thanks.

Answer 1

In the example, a row conversion function is passed to d3.csv to parse the dates. Since d3.json doesn't take a row conversion function, you need to parse the dates yourself after the data is loaded:

d3.json("mydata.json", function(error, data) {
  if (error) throw error;

  data.forEach(function(d) {
    d.date = parseDate(d.date);
  });

  ...
}