Use JSON file with chart.js

Question

I've been looking all over chart.js-related questions, but not two developers seem to be giving the same answer on how to display a chart using chart.js + JSON.

I am trying to display a chart using a JSON file - specifically a list of "amounts" with their relative labels ("January 2017",...).

The chart canva display just fine, no console log error, but no chart itself. What am I missing?

Thanks!

Here my chart.js code:-

var labels = [];
var data = [];

$.getJSON("https://jsonblob.com/api/jsonBlob/26078b70-6b6f-11e7-a38a-bf689f57642c"), function (data) {
  $.each(data.customers.amounts, function(key, value){
    var labels = json.map(function(item) {
      labels.push(item.key);
   });
    var data = json.map(function(item) {
      data.push(item.value);
   });
   });
}

var ctx = document.getElementById('myChart').getContext('2d');
var chart = new Chart(ctx, {
    type: 'line',
    data: {
        datasets: [{
            labels: labels,
            backgroundColor: 'rgb(129, 198, 2228)',
            borderColor: 'rgb(0, 150, 215)',
            data: data
        }]
    },
    options: {
      responsive: 'true',
    }
});

and here's my JSON file:-

{
  "customers": [
    {
      "first_name": "John",
      "last_name": "Doe",
      "account": "123456",
      "period": "13th July - 13th August",
      "due_date": "14th September",
      "amounts": [
        ["January 2017", 121.23],
        ["February 2017", 145.23],
        ["March 2017", 55.12],
        ["April 2017", 78.58],
        ["May 2017", 89.13],
        ["June 2017", 45.78],
        ["July 2017", 90.22]
      ]
    }
  ]
}

you are accessing amounts using data.customers.amounts, but customers itself is another, shouldn't you access it using data.customers[0].amounts — Akash Shinde
– Akash Shinde, Commented Jul 24, 2017 at 5:44

ɢʀᴜɴᴛ · Accepted Answer · 2017-07-24 06:29:47Z

4

Couple of Issues :

since $.getJSON() method is asynchronous, you should construct the chart inside it's callback function.
you are looping through the response data incorrectly. could be as simple as :

    var labels = data.customers[0].amounts.map(function(e) {
       return e[0];
    });

    var data = data.customers[0].amounts.map(function(e) {
       return e[1];
    });

you are adding labels array to your dataset, while it belogns to the data object.

Here is the revised version of your code :

$.getJSON("https://jsonblob.com/api/jsonBlob/26078b70-6b6f-11e7-a38a-bf689f57642c", function(data) {
   var labels = data.customers[0].amounts.map(function(e) {
      return e[0];
   });
   var data = data.customers[0].amounts.map(function(e) {
      return e[1];
   });

   var ctx = document.getElementById('myChart').getContext('2d');
   var chart = new Chart(ctx, {
      type: 'line',
      data: {
         labels: labels,
         datasets: [{
            backgroundColor: 'rgb(129, 198, 2228)',
            borderColor: 'rgb(0, 150, 215)',
            data: data
         }]
      },
      options: {
         responsive: 'true',
      }
   });
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.6.0/Chart.min.js"></script>
<canvas id="myChart"></canvas>

answered Jul 24, 2017 at 6:29

ɢʀᴜɴᴛ

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2 Comments

Stefan Over a year ago

You are my hero! :) Could you explain a little bit more in detail what is happening for this line, so I can understand better: var labels = data.customers[0].amounts.map(function(e) { return e[0]; });

ɢʀᴜɴᴛ Over a year ago

It creates a new array with all the labels from data.customers[0].amounts array, using Array#map

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