google.visualization.DataTable和linechar

Question

我的直线没有画任何线。这是我的密码：

    dataC = new google.visualization.DataTable();
    dataC.addColumn('datetime', 'Datum');
    dataC.addColumn('number', 'Temp1');
    dataC.addColumn('number', 'Temp2');
    dataC.addColumn('number', 'Temp3');
    dataC.addColumn('number', 'Temp4');

    var optionsC = {
      title: 'Temperaturen',
      curveType: 'function',
      legend: { position: 'bottom' },
      series: { 4: { type: 'line' }, 3: { type: 'line' }, 2: { type: 'line' }, 1: { type: 'line' }}
    };

    chart = new google.visualization.LineChart(document.getElementById('curve_chart'));

    $.getJSON("https://api.thingspeak.com/channels/" + channel_id + "/feeds.json?api_key=" + api_key + "&results=5", function(json1) {
    json1.feeds.forEach(function(feed,i){
    //console.log("\n The details of " + i + "th Object are :  \nCreated_at: " + feed.created_at + "\nEntry_id:" + feed.entry_id + "\nField1:" + feed.field1 + "\nField2:" + feed.field2+"\nField3:" + feed.field3);      
    my_json = feed;
    //console.log(my_json); //Object {created_at: "2017-03-14T01:00:32Z", entry_id: 33358, field1: "4", field2: "4", field3: "0"}
    var data = [];
    for(var i in my_json)
      data.push(my_json [i]);

    var data2 = [new Date(data[0]),parseInt(data[2]),parseInt(data[3]),parseInt(data[4]),parseInt(data[5])];
    console.log(data2);
    dataC.addRow([new Date(data[0]),parseInt(data[2]),parseInt(data[3]),parseInt(data[4]),parseInt(data[5])]);
    });

    });
    //console.log(dataC.length);
    chart.draw(dataC, optionsC);

我有四个温度，我想在图表中画出来。这里怎么了？？我的阵列看起来很好..。请帮帮忙

Answer 1

getJSON是异步的，这意味着图表是在加载数据之前绘制的。

将chart.draw移动到getJSON内部，如下所示..。

$.getJSON("https://api.thingspeak.com/channels/" + channel_id + "/feeds.json?api_key=" + api_key + "&results=5", function(json1) {
  json1.feeds.forEach(function(feed,i){
    //console.log("\n The details of " + i + "th Object are :  \nCreated_at: " + feed.created_at + "\nEntry_id:" + feed.entry_id + "\nField1:" + feed.field1 + "\nField2:" + feed.field2+"\nField3:" + feed.field3);      
    my_json = feed;
    //console.log(my_json); //Object {created_at: "2017-03-14T01:00:32Z", entry_id: 33358, field1: "4", field2: "4", field3: "0"}
    var data = [];
    for(var i in my_json)
      data.push(my_json [i]);

    var data2 = [new Date(data[0]),parseInt(data[2]),parseInt(data[3]),parseInt(data[4]),parseInt(data[5])];
    console.log(data2);
    dataC.addRow([new Date(data[0]),parseInt(data[2]),parseInt(data[3]),parseInt(data[4]),parseInt(data[5])]);
  });

  //console.log(dataC.length);
  chart.draw(dataC, optionsC);

});