使用CodeIgniter基于JSON数据创建Google饼图(Creating Google Pie Chart based on JSON data using CodeIgniter)

 我试着在这里基于例子创建一个饼图 
 
 在我的控制器（mycontroller / json）中，我有以下代码： 
 
public function json(){

$whatever = '{
"cols": [
    {"id":"","label":"Topping","pattern":"","type":"string"},
    {"id":"","label":"Slices","pattern":"","type":"number"}
  ],
"rows": [
    {"c":[{"v":"Mushrooms","f":null},{"v":3,"f":null}]},
    {"c":[{"v":"Onions","f":null},{"v":1,"f":null}]},
    {"c":[{"v":"Olives","f":null},{"v":1,"f":null}]},
    {"c":[{"v":"Zucchini","f":null},{"v":1,"f":null}]},
    {"c":[{"v":"Pepperoni","f":null},{"v":2,"f":null}]}
  ]
}';
echo $whatever;
}
 
 在我看来，我有以下代码（部分代码显示） 
 
var jsonData = $.ajax({
    url: "<?= base_url()?>index.php/bunker/json",
    dataType:"json",
    async: false
    }).responseText;

// Create and populate the data table.
var popularCategory = google.visualization.DataTable(jsonData);
new google.visualization.PieChart(document.getElementById('category')).draw(popularCategory,
    {title:"Popularity by Category"});
 
 最后我有一个名为'category'的div。 但是，我总是收到一条消息，说明数据未定义。 
 
 使用firebug进行快速调试，我没有收到任何错误，$ whatever变量也被视为正确的JSON格式。 我在这里犯了什么错误？ 
 
 干杯， 

I tried to create a pie chart based on example here
 
In my controller (mycontroller/json) i have the following code:
 
public function json(){

$whatever = '{
"cols": [
    {"id":"","label":"Topping","pattern":"","type":"string"},
    {"id":"","label":"Slices","pattern":"","type":"number"}
  ],
"rows": [
    {"c":[{"v":"Mushrooms","f":null},{"v":3,"f":null}]},
    {"c":[{"v":"Onions","f":null},{"v":1,"f":null}]},
    {"c":[{"v":"Olives","f":null},{"v":1,"f":null}]},
    {"c":[{"v":"Zucchini","f":null},{"v":1,"f":null}]},
    {"c":[{"v":"Pepperoni","f":null},{"v":2,"f":null}]}
  ]
}';
echo $whatever;
}
 
In my view i have the following code (partial code is shown)
 
var jsonData = $.ajax({
    url: "<?= base_url()?>index.php/bunker/json",
    dataType:"json",
    async: false
    }).responseText;

// Create and populate the data table.
var popularCategory = google.visualization.DataTable(jsonData);
new google.visualization.PieChart(document.getElementById('category')).draw(popularCategory,
    {title:"Popularity by Category"});
 
And lastly i have a div with an id called 'category'. However, i always get a message saying data is not defined.
 
A quick debug using firebug, i receive no error, the $whatever variable is also treated as a proper JSON format. What mistakes have i made here?
 
cheers,

原文：https://stackoverflow.com/questions/16317138