Loading an external JSON into ChartJs

Question

I am a newbie when it comes to using libraries for drawing charts in JavaScript/ I just started experimenting with Chartjs and I have been unable to how to use getJson or anything else to load my json object and replace the labels and data. I have used HighCharts before and its quite simple compared to this. Also, how would I go about putting this into a directive in Angular and displaying it.

https://jsfiddle.net/0u9Lpttx/1/

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<div style="width: 100%; height: 100%;">
    <canvas id="myChart" style="width: 100%; height: auto;"></canvas>
</div>
<div id="js-legend" class="chart-legend"></div>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script src="http://ajax.googleapis.com/ajax/libs/angularjs/1.0.6/angular.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/Chart.js/1.0.1/Chart.min.js"></script>
<script src="js/chartJsControl.js"></script>
</body>
</html>

data.json

[
  {
    "timestamp": "Monday",
    "original_tweet": "756",
    "retweets": "345",
    "shared": "34",
    "quoted": "14"
  },
  {
    "timestamp": "Tuesday",
    "original_tweet": "756",
    "retweets": "345",
    "shared": "34",
    "quoted": "14"
  },
  {
    "timestamp": "Wednesday",
    "original_tweet": "756",
    "retweets": "345",
    "shared": "34",
    "quoted": "14"
  }
]

chartJsControl.js

var test = [];
$.getJSON("data.json", function (json) {
    test.push(json[i].timestamp);

});
var data = {
    labels: test,
    datasets: [
        {
            label: "My First dataset",
            fillColor: "rgba(220,220,220,0.5)",
            strokeColor: "rgba(220,220,220,0.8)",
            highlightFill: "rgba(220,220,220,0.75)",
            highlightStroke: "rgba(220,220,220,1)",
            data: [65, 59, 80, 81, 56, 55, 40]
        },
        {
            label: "My Second dataset",
            fillColor: "rgba(151,187,205,0.5)",
            strokeColor: "rgba(151,187,205,0.8)",
            highlightFill: "rgba(151,187,205,0.75)",
            highlightStroke: "rgba(151,187,205,1)",
            data: [28, 48, 40, 19, 86, 27, 90]
        }
    ]
};


var ctx = document.getElementById("myChart").getContext("2d");
ctx.canvas.width = 1000;
ctx.canvas.height = 800;

var myChart = new Chart(ctx).Bar(data);

the creation of the chart must be inside the getJSON callback function. Only then you can use the returning json — Betty St, Oct 06 '15 at 18:49
@user2402107 you could think of angular version of `chart.js` take a look at this answer http://stackoverflow.com/a/28278459/2435473 — Pankaj Parkar, Oct 06 '15 at 18:57

score 6 · Accepted Answer · answered Oct 06 '15 at 19:07

6

If you want to use the returned JSON from data.json you need to do this in the callback function like this:

$.getJSON("data.json", function (json) {
  // will generate array with ['Monday', 'Tuesday', 'Wednesday']
  var labels = json.map(function(item) {
    return item.timestamp;
  });

  var data = {
    labels: labels,
    datasets: [
    {
      label: "My First dataset",
      fillColor: "rgba(220,220,220,0.5)",
      strokeColor: "rgba(220,220,220,0.8)",
      highlightFill: "rgba(220,220,220,0.75)",
      highlightStroke: "rgba(220,220,220,1)",
      data: [65, 59, 80, 81, 56, 55, 40]
    },
    {
      label: "My Second dataset",
      fillColor: "rgba(151,187,205,0.5)",
      strokeColor: "rgba(151,187,205,0.8)",
      highlightFill: "rgba(151,187,205,0.75)",
      highlightStroke: "rgba(151,187,205,1)",
      data: [28, 48, 40, 19, 86, 27, 90]
    }
    ]
  };

  var ctx = document.getElementById("myChart").getContext("2d");
  ctx.canvas.width = 1000;
  ctx.canvas.height = 800;

  var myChart = new Chart(ctx).Bar(data);
});

If you are using it with Angular I would recommend using the angular chart.js version, see: http://jtblin.github.io/angular-chart.js/

Then you already have an angular directive, which you can use!

answered Oct 06 '15 at 19:07

Betty St

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1

A while ago, I wrote an blog article where I compared different angular chart libraries: https://lingohub.com/blog/2014/06/comparison-angularjs-directives-charts-front-end-app-development/ – Betty St Oct 06 '15 at 19:10
Actually here is a tougher question. Its working perfectly now but I want to break each json object per day so that Monday it is a grouped chart but right now its just giving me the same data set back – user2402107 Oct 06 '15 at 19:17
I don't understand ? Maybe you just need to iterate over your ``json`` and fill the ``datasets`` array. – Betty St Oct 06 '15 at 19:20
Like I want each json for each day to be its own grouped bar chart on the canvas. Right now however its grouping the two data sets together. – user2402107 Oct 06 '15 at 19:22
I don't know how you can do grouped bar charts with Chart.js, sorry! – Betty St Oct 06 '15 at 19:23

Loading an external JSON into ChartJs

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