从 JSON 使用 Google Charts API 创建饼图答案

【问题标题】：Creating Pie Chart with Google Charts API from JSON从 JSON 使用 Google Charts API 创建饼图
【发布时间】：2016-08-13 19:10:59
【问题描述】：

现在我正在尝试从我的 MySQL 数据库的 JSON 输出创建一个饼图。我对 JavaScript 很陌生，这就是为什么我向您寻求帮助的原因。我找到了以下project 并对其进行了一些更改。但是现在我的问题是我的饼图中要添加 81 个不同的值，但是如果我尝试在 data.addRow() 中添加更多数据，我会收到一个错误，即数据多于预期。如何加载饼图的所有行？

<script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>
<script type="text/javascript">
 var data;
 var chart;

  // Load the Visualization API and the piechart package.
  google.charts.load('current', {'packages':['corechart']});

  // Set a callback to run when the Google Visualization API is loaded.
  google.charts.setOnLoadCallback(drawChart);

  // Callback that creates and populates a data table,
  // instantiates the pie chart, passes in the data and
  // draws it.
  function drawChart() {


    var jsonData = $.ajax({
                    url: "FetchDate.php",
                    dataType:"json",
                    async: false
                    }).done(function (results) {

      var data = new google.visualization.DataTable();

      data.addColumn('string', 'VoteName');
      data.addColumn('number', 'VoteCount');

      $.each(results, function (i, row) {
        var strData = "vt".concat(i);
        data.addRow([
          strData,
          parseFloat(row.vt0)
        ]);
      });
  });

    // Set chart options
    var options = {'title':'My Pie Chart',
                   'width':600,
                   'height':600};

    // Instantiate and draw our chart, passing in some options.
    chart = new google.visualization.PieChart(document.getElementById('chart_div'));
    google.visualization.events.addListener(chart, 'select', selectHandler);
    chart.draw(data, options);
  }

  function selectHandler() {
    var selectedItem = chart.getSelection()[0];
    var value = data.getValue(selectedItem.row, 0);
    alert('The user selected ' + value);
  }

</script>

还有我的 JSON 输出：

[{"id":"1","name":"improvisiertester Unterricht","vt0":"0","vt1":"0","vt2":"0","vt3":"0","vt4":"1","vt5":"0","vt6":"0","vt7":"0","vt8":"0","vt9":"0","vt10":"0","vt11":"0","vt12":"0","vt13":"0","vt14":"0","vt15":"0","vt16":"0","vt17":"0","vt18":"0","vt19":"0","vt20":"0","vt21":"0","vt22":"0","vt23":"0","vt24":"0","vt25":"0","vt26":"0","vt27":"0","vt28":"3","vt29":"2","vt30":"0","vt31":"12","vt32":"0","vt33":"0","vt34":"0","vt35":"1","vt36":"0","vt37":"0","vt38":"0","vt39":"0","vt40":"1","vt41":"2","vt42":"0","vt43":"0","vt44":"1","vt45":"0","vt46":"1","vt47":"0","vt48":"0","vt49":"0","vt50":"0","vt51":"0","vt52":"0","vt53":"0","vt54":"0","vt55":"0","vt56":"0","vt57":"0","vt58":"1","vt59":"0","vt60":"1","vt61":"0","vt62":"0","vt63":"0","vt64":"0","vt65":"0","vt66":"0","vt67":"0","vt68":"0","vt69":"0","vt70":"0","vt71":"0","vt72":"0","vt73":"0","vt74":"0","vt75":"0","vt76":"0","vt77":"0","vt78":"0","vt79":"0","vt80":"0","vt81":"0","alreadyVoted":",66,78,30,67,39,37,79,75,81,32,11,3,56,18,28,46,16,6,17,9,35,64,58,68,41"}]

说明： id 是我的问题中的特定 id 名字就是问题 vt1-81 是可能的答案以及有人投票的频率 alreadyVoted 存储所有投票的用户 ID

感谢您的时间和工作！！！

【问题讨论】：

标签： javascript html json charts google-visualization

【解决方案1】：

帖子中的 JSON 包含一个具有一个元素的数组，该数组具有多个键...

所以不要使用$.each 迭代元素，而是使用Object.keys...

请参阅以下工作示例...

var data;
var chart;

google.charts.load('current', {
  callback: drawChart,
  packages:['corechart']
});

function drawChart() {
  var results = [{"id":"1","name":"improvisiertester Unterricht","vt0":"0","vt1":"0","vt2":"0","vt3":"0","vt4":"1","vt5":"0","vt6":"0","vt7":"0","vt8":"0","vt9":"0","vt10":"0","vt11":"0","vt12":"0","vt13":"0","vt14":"0","vt15":"0","vt16":"0","vt17":"0","vt18":"0","vt19":"0","vt20":"0","vt21":"0","vt22":"0","vt23":"0","vt24":"0","vt25":"0","vt26":"0","vt27":"0","vt28":"3","vt29":"2","vt30":"0","vt31":"12","vt32":"0","vt33":"0","vt34":"0","vt35":"1","vt36":"0","vt37":"0","vt38":"0","vt39":"0","vt40":"1","vt41":"2","vt42":"0","vt43":"0","vt44":"1","vt45":"0","vt46":"1","vt47":"0","vt48":"0","vt49":"0","vt50":"0","vt51":"0","vt52":"0","vt53":"0","vt54":"0","vt55":"0","vt56":"0","vt57":"0","vt58":"1","vt59":"0","vt60":"1","vt61":"0","vt62":"0","vt63":"0","vt64":"0","vt65":"0","vt66":"0","vt67":"0","vt68":"0","vt69":"0","vt70":"0","vt71":"0","vt72":"0","vt73":"0","vt74":"0","vt75":"0","vt76":"0","vt77":"0","vt78":"0","vt79":"0","vt80":"0","vt81":"0","alreadyVoted":",66,78,30,67,39,37,79,75,81,32,11,3,56,18,28,46,16,6,17,9,35,64,58,68,41"}];

  data = new google.visualization.DataTable();
  data.addColumn('string', 'VoteName');
  data.addColumn('number', 'VoteCount');

  // iterate "vt" keys
  Object.keys(results[0]).forEach(function (key) {
    if (key.indexOf("vt") > -1) {
      data.addRow([
        key,
        parseFloat(results[0][key])
      ]);
    }
  });

  var options = {
    title: 'My Pie Chart',
    width: 600,
    height: 600
  };

  chart = new google.visualization.PieChart(document.getElementById('chart_div'));
  google.visualization.events.addListener(chart, 'select', selectHandler);
  chart.draw(data, options);
}

function selectHandler() {
  // be sure something is selected
  if (chart.getSelection().length) {
    var selectedItem = chart.getSelection()[0];
    var value = data.getValue(selectedItem.row, 0);
    alert('The user selected ' + value);
  }
}

<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>

添加 ajax 回调看起来像这样......

var data;
var chart;

google.charts.load('current', {
  callback: drawChart,
  packages:['corechart']
});

function drawChart() {
  data = new google.visualization.DataTable();
  data.addColumn('string', 'VoteName');
  data.addColumn('number', 'VoteCount');

  var jsonData = $.ajax({
    url: "FetchDate.php",
    dataType:"json",
    async: false
  }).done(function (results) {
    // iterate "vt" keys
    Object.keys(results[0]).forEach(function (key) {
      if (key.indexOf("vt") > -1) {
        data.addRow([
          key,
          parseFloat(results[0][key])
        ]);
      }
    });
  });

  var options = {
    title: 'My Pie Chart',
    width: 600,
    height: 600
  };

  chart = new google.visualization.PieChart(document.getElementById('chart_div'));
  google.visualization.events.addListener(chart, 'select', selectHandler);
  chart.draw(data, options);
}

function selectHandler() {
  // be sure something is selected
  if (chart.getSelection().length) {
    var selectedItem = chart.getSelection()[0];
    var value = data.getValue(selectedItem.row, 0);
    alert('The user selected ' + value);
  }
}

【讨论】：

它几乎可以工作，但我怎样才能从我的 jsonData 中获取这些数据？对不起，如果这个问题很明显，但我是 JS 新手。
不幸的是，我的控制台出现错误：dia2.php:31 Uncaught TypeError: Cannot read property 'addRow' of undefined
确保您已经定义了一次data。在原始帖子中，您在顶部定义 -- var data; 并再次在 drawChart
谢谢它知道。正如你所说，数据被多次定义。

【解决方案2】：

var data;
var chart;
google.charts.load('current', {
callback: drawChart,
packages: ['corechart']});
function drawChart() {
var results = [{"count":1,"year":"2009 "},{"count":3,"year":"2011 "},{"count":5,"year":"2012 "},{"count":9,"year":"2013 "},{"count":2,"year":"2014 "},{"count":1,"year":"2015 "},{"count":59,"year":"2016 "},{"count":4,"year":"2017 "}]
data = new google.visualization.DataTable();
data.addColumn('string', 'VoteName');
data.addColumn('number', 'VoteCount');
results.forEach(function(data1, index) {
data.addRow([data1.year,data1.count]);
});
var options = {title: 'My Pie Chart- Lujan',
width: 600,
height: 600};
chart = new google.visualization.PieChart(document.getElementById('chart_div'));
google.visualization.events.addListener(chart, 'select', selectHandler);
chart.draw(data, options);}
function selectHandler() {
// be sure something is selected
if (chart.getSelection().length) {
var selectedItem = chart.getSelection()[0];
var value = data.getValue(selectedItem.row, 0);
alert('The user selected ' + value);}
} **strong text**
<script src="https://www.gstatic.com/charts/loader.js"></script>
<div id="chart_div"></div>

【讨论】：

在这个适用于 WhiteHat 的示例中，JSON 具有另一种结构。在 foreach 中也发生了变化。