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

问题

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

回答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);
                }
            }
        });
    }
}

回答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

来源：https://stackoverflow.com/questions/38344582/how-to-show-data-values-or-index-labels-in-chartjs-latest-version