如何为chart.js折线图动态创建数据集？

Question

我想在chart.js库中动态创建带有多个数据集的折线图。

我已经能够动态地分配数据。但我想动态创建数据集本身。我看到了下面的链接：

如何为chart.js从html表格中动态添加元素

并尝试了这个：

var datasetValue = [];
for (var j = 0; j < count; j++) {
datasetValue[j] = [
{
fillColor: 'rgba(220,220,220,0.5)',
strokeColor :'rgba(220,220,220,1)' ,
title :'2013',
data : [Math.round(Math.random() * 100),Math.round(Math.random() * 100)-10]
}]
}

var mydata = {
datasets : datasetValue
}

这里的计数值为3，我希望在图表中显示3条线，并且计数值会变化。即使图表线条的颜色和标题相同，我想首先显示该线条，并在解决此问题后更改其余部分。

我尝试像这样访问数据：

alert("Datasets:"+mydata.datasets[0].data);

它应该显示第一个数据集的数据，但实际上却显示了undefined。

然而，在下面的情况下：

var mydata1 = {
labels : ["January","February","March","April","May","June","July"],
datasets : [
    {
        fillColor : "rgba(220,220,220,0.5)",
        strokeColor : "rgba(220,220,220,1)",
        data : [95,53,99,73,27,82,40],
        title : "2014"
    },
    {
        fillColor : "rgba(151,187,205,0.5)",
        strokeColor : "rgba(151,187,205,1)",
        data : [35,43,59,31,50,66,55],
        title : "2013"
    }
 ]
}

alert("Datasets:"+mydata1.datasets[0].data);

我可以获取第一个数据集的数据。请问有什么解决方案吗？

- Suresh

Answer 1

我认为您正在寻找以下解决方案。

http://jsfiddle.net/5m63232a/

var datasetValue = [];
var count = 10;
for (var j=0; j<count; j++) {
    datasetValue[j] = {
        fillColor: 'rgba(220,220,220,0.5)',
        strokeColor :'rgba(220,220,220,1)',
        title :'2013',
        data : [Math.round(Math.random() * 100),Math.round(Math.random() * 100)-10]
    }
}
var mydata = {
    datasets : datasetValue
}
alert("Datasets: "+mydata.datasets[0].data);

- Bear GRiZZLY Xi

---

嗨，Bear GRiZZLY Xi，我刚刚得到了这个解决方案，非常感谢你的快速回复。 - Suresh

@Suresh，能分享一下你得到的解决方案吗？ - Vladd

Answer 2

创建服务来获取JSON格式的数据，例如：

labels : ["January","February","March","April","May","June","July"],
        datasets : [
            {
                label: "My First dataset",
                fillColor : "rgba(220,220,220,0.2)",
                strokeColor : "rgba(220,220,220,1)",
                pointColor : "rgba(220,220,220,1)",
                pointStrokeColor : "#fff",
                pointHighlightFill : "#fff",
                pointHighlightStroke : "rgba(220,220,220,1)",
                data : [randomScalingFactor(),randomScalingFactor(),randomScalingFactor(),randomScalingFactor(),randomScalingFactor(),randomScalingFactor(),randomScalingFactor()]
            },
            {
                label: "My Second dataset",
                fillColor : "rgba(151,187,205,0.2)",
                strokeColor : "rgba(151,187,205,1)",
                pointColor : "rgba(151,187,205,1)",
                pointStrokeColor : "#fff",
                pointHighlightFill : "#fff",
                pointHighlightStroke : "rgba(151,187,205,1)",
                data : [randomScalingFactor(),randomScalingFactor(),randomScalingFactor(),randomScalingFactor(),randomScalingFactor(),randomScalingFactor(),randomScalingFactor()]
            }
        ]  

然后添加以下JavaScript代码。

var j = [];
$.ajax({
    type: 'GET',
    url: 'http://' + window.location.host.toString() + "/path",
    dataType: 'json',
    success: function (data) {
       j = data;
    },
    async: false
 });
 var chartData = {
     labels: j.labels,
     datasets: j.datasets
 };
 window.onload = function () {
     var ctx = document.getElementById("canvas").getContext("2d");
     window.myLine = new Chart(ctx).Line(chartData, {
         responsive: true,
         animation: true,
         tooltipFillColor: "rgba(0,0,0,0.8)",
         multiTooltipTemplate: "<%= datasetLabel %> - <%=value %>"
     });
 }

- Bhuwan Prasad Upadhyay