javascript - 使用json数据在chart.js中绘制折线图

Question

我正在尝试使用来自 MongoDB 的 JSON 响应绘制折线图。我认为我的代码不正确，我不断收到 this error

我试过这个。

myurl = "/api/humidity"
$(function() {
    $.ajax({
        type: "GET",
        url: myurl,
        cache: false,
        dataType : "json",
        success: function (data1) {
         //   console.log(data);
            $.each(data1.when, function(position, when) {

                if (data1.when) {

                    chartData.labels.push(data1.when);
                } else {

                    chartData.labels.push('');
                }
                chartData.datasets[0].data.push(data.message);

            });
        }
    })
})


var chartData = {
    labels: [],
    datasets: [
        {
            label: "Humidity",
            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: []
        },

    ]
};


var ctx = document.getElementById("myChart").getContext("2d");
var myChart = new Chart(ctx).Line (chartData, {

});

最终我希望我的代码能够迭代数据库中的项目直到完成。

这就是我的 JSON 数据的样子

[{
    "_id": "585b544f5c86b6c8537c34d6",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:27.000Z"
}, {
    "_id": "585b54505c86b6c8537c34d7",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:28.000Z"
}, {
    "_id": "585b54515c86b6c8537c34d8",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:29.000Z"
}, {
    "_id": "585b54525c86b6c8537c34d9",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:30.000Z"
}, {
    "_id": "585b54535c86b6c8537c34da",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:31.000Z"}]

如果有任何帮助或建议，我将不胜感激。

Answer 1

您可以尝试使用 Chart.js 版本 2.2

var cdata = [{
    "_id": "585b544f5c86b6c8537c34d6",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:27.000Z"
}, {
    "_id": "585b54505c86b6c8537c34d7",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:28.000Z"
}, {
    "_id": "585b54515c86b6c8537c34d8",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:29.000Z"
}, {
    "_id": "585b54525c86b6c8537c34d9",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:30.000Z"
}, {
    "_id": "585b54535c86b6c8537c34da",
    "topic": "Humidity",
    "message": 23,
    "when": "2016-12-22T04:19:31.000Z"
}]

var labeldata = [];

var chrtdata = [];

for(var i =0; i < cdata.length; i++)
{
  labeldata.push(cdata[i].when);
  chrtdata.push(cdata[i].message)
}




var ctx = document.getElementById("myChart").getContext("2d");
var myChart = new Chart(ctx, {
  type: 'line',
  data: {
    labels: labeldata,
    datasets: [{
      label: 'Humidity',
      data: chrtdata,
      backgroundColor: "rgba(153,255,51,0.6)"
    }]
  }
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.2.2/Chart.min.js"></script>
 <div>
    <canvas id="myChart"></canvas>
  </div>