AmCharts 4处理空数据

Question

I am working on AmCharts where I load data dynamically. Sometimes, there may be null data sent from the response. I need to handle null data in AmCharts4. In this link I see the example for Amcharts3 handling null data

var chart = am4core.create("reason_for_failure", am4charts.PieChart);
        // Add and configure Series
        var pieSeries = chart.series.push(new am4charts.PieSeries());
        pieSeries.dataFields.value = "litres";
        pieSeries.dataFields.category = "country";
        pieSeries.slices.template.stroke = am4core.color("#fff");
        pieSeries.slices.template.strokeWidth = 2;
        pieSeries.slices.template.strokeOpacity = 1;

        // This creates initial animation
        pieSeries.hiddenState.properties.opacity = 1;
        pieSeries.hiddenState.properties.endAngle = -90;
        pieSeries.hiddenState.properties.startAngle = -90;

        chart.data = [];

Answer 1

It looks like the sample code he provided is more/less straight out of one of our Pie Chart demos, eg Pie Chart With Legend , so I mixed and matched that with the solution in the mirror GitHub issue (demo link on the bottom).

Again, the beforevalidated event is perfect for handling the case of the chart.data being assigned an empty array, eg

chart.events.on("beforevalidated", function(event) {
  // check if there's data
  console.log(event.target.data.length);
  if (event.target.data.length == 0) {
    // handle null data here
  }
});

It would have to be the beforevalidated event, because if there's no data, beforedatavalidated does not trigger.

Demo:

https://codepen.io/team/amcharts/pen/88d11b5385a2669319c1a0fcdaa1e199/