How to use the tooltipTemplate on Chart.JS 2.0

Question

I am trying to use the doughnut chart with multiple datasets and also use the tooltipTemplate feature to customize the text inside the tooltips but nothing works. This worked in the previous Chart js version but that doesn't support multiple datasets. Can anyone help? Below is my code:

options: {
    tooltips: {
        tooltipTemplate: "<%if (label){%><%=value%><%} else {%> No data <%}%>",
    },
}

Answer 1

As potatopeelings has mentioned in the comments, you have to set a callback for the tooltip.

Here is an example:

options: {
  tooltips: {
    callbacks: {
      label: function(tooltipItem, data) {
        var datasetLabel = data.datasets[tooltipItem.datasetIndex].label || 'Other';
        var label = data.labels[tooltipItem.index];
        return datasetLabel + ': ' + label;
      }
    }
  }
}

live demo

var ctx = document.getElementById("myChart");
var myChart = new Chart(ctx, {
    type: 'doughnut',
    data: {
        labels: ["Men", "Women", "Unknown"],
        datasets: [{
            label: 'Sweden',
            data: [60, 40, 20],
            backgroundColor: ['rgba(158, 216, 202, 0.75)', 'rgba(255, 150, 162, 0.75)', 'rgba(160, 160, 160, 0.75)']
        }, {
            label: 'Netherlands',
            data: [40, 70, 10],
            backgroundColor: ['rgba(158, 216, 202, 0.5)', 'rgba(255, 150, 162, 0.5)', 'rgba(160, 160, 160, 0.5)']
        }, {
            data: [33, 33, 34],
            backgroundColor: ['rgba(158, 216, 202, 0.25)', 'rgba(255, 150, 162, 0.25)', 'rgba(160, 160, 160, 0.25)']
        }]
    },
    options: {
        tooltips: {
            callbacks: {
                label: function(tooltipItem, data) {
                    var datasetLabel = data.datasets[tooltipItem.datasetIndex].label || 'Other';
                    var label = data.labels[tooltipItem.index];
                    return datasetLabel + ': ' + label;
                }
            }
        }
    }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.1.2/Chart.min.js"></script>
<canvas id="myChart" width="400" height="200"></canvas>