How to show data values or index labels in ChartJs (Latest Version)

Question

How to show data values or index labels in ChartJs (Latest Version) as in the below image:

I am using the ChartJs to display charts in my React Project. Everything is working fine, except this.

I found an answer in stackoverflow (https://stackoverflow.com/a/31632707), But it uses an old version of chartjs and is not working on the one which I am using.

My ChartJs Code:

var ctx = document.getElementById("myChart");

var BarChart = new Chart(ctx, {
    type: 'bar',
    data: {
        labels: ["Jan","Feb","March"],
        datasets: [{
            label: "Chart Data",
            data: [10,20,15],
            backgroundColor: "red",
            borderColor: "green",
            borderWidth: 1
        }]
    },
    options: {
        legend: {
            display: false
        },
        scales: {
            yAxes: [{
                ticks: {
                    beginAtZero: true
                }
            }],
            xAxes: [{
                ticks: {
                    maxRotation: 180
                }
            }]
        }
    }
});

I tried adding it using the function: ctx.fillText(bar.value, bar.x, bar.y - 5);, But its showing .fillText is not a function

Literature

Is ctx defined when you call this? .fillText() is a canvas function and should be there. Maybe it is just your declaration. I think it should be var ctx = document.getElementById("myChart").getContext("2d"); – Antitrust

Yes. I console logged it in the console. And it works fine. – Literature

Let me check that by adding .getContext("2d") – Literature

Now the .fillText() is working fine. But it shows this.datasets as undefined. But console.log(this) => {chart: t, config: Object, options: Object, id: 0, titleBlock: n…} But this object does not contain the datasets object – Literature

You should find your dataset in chart.config.data – Antitrust

Yes. I already tried that, but the chart.config.data does not contain the bars array. Also it does not contain the x and y values – Literature

@Antitrust : is there any way to get the datasets x and y values? – Literature

Answer 1

Finally I got it working.

Used the following code in the onComplete() function:

animation: {
    onComplete: function () {
        var ctx = this.chart.ctx;
        ctx.font = Chart.helpers.fontString(Chart.defaults.global.defaultFontFamily, 'normal', Chart.defaults.global.defaultFontFamily);
        ctx.fillStyle = "black";
        ctx.textAlign = 'center';
        ctx.textBaseline = 'bottom';

        this.data.datasets.forEach(function (dataset)
        {
            for (var i = 0; i < dataset.data.length; i++) {
                for(var key in dataset._meta)
                {
                    var model = dataset._meta[key].data[i]._model;
                    ctx.fillText(dataset.data[i], model.x, model.y - 5);
                }
            }
        });
    }
}

Literature

Answer 2

Got it to work after some researching.

You have to set it after in the onComplete event of the animation. The x, y values of the bars are stored in the model of the children (point, line, bar, whatever)

onComplete: function () {
                var ctx = this.chart.ctx;
                ctx.font = Chart.helpers.fontString(Chart.defaults.global.defaultFontFamily, 'normal', Chart.defaults.global.defaultFontFamily);
                ctx.textAlign = 'center';
                ctx.textBaseline = 'bottom';

                this.data.datasets.forEach(function (dataset) {
                    for (var i = 0; i < dataset.data.length; i++) {
                            console
                        var model = dataset._meta[0].dataset._children[i]._model;
                        ctx.fillText(dataset.data[i], model.x, model.y - 5);
                    }
                });               
            }

Just the structure changed a little bit.

You can see it in this working JSFiddle

Antitrust

Again got with an error :( var model = dataset._meta[0].dataset._children[i]._model; In this statement I am getting an error saying Cannot read property '_children' of null For me dataset._meta[0].dataset is null – Literature

KRONWALLED: Thank you for your guidance :) – Literature

Hi there, Can someone guide me how to do this in react? – Forswear

Getting this error dataset._meta[0].dataset is null. Any idea? – Kaiserism