使用Google Chart API和JSON for DataTable创建折线图(Create line chart using Google Chart API and JSON for DataTable)

 我正在尝试使用Google Chart API创建折线图。 我正尝试通过AJAX帖子为数据表使用JSON设置数据。 
 
 我有一个为饼图工作的版本，但我无法找到如何为折线图做。 
 
 以下是我如何使用ajax创建图表。 
 
function drawLineGraph()
             {
                 $.post("loadGraph.php",
                    {
                        type: "line"
                    },
                    function (result)
                    {
                        var data = new google.visualization.DataTable(result);
                        var options = {
                            title: "Line Graph Test"
                        };

                        var chart = new google.visualization.LineChart(document.getElementById("lineChart"));
                        chart.draw(data, options);
                    }, "json"
                );
             }
 
 下面是loadGraph.php的代码 
 
print json_encode(test());

    function test()
    {
        $array = array();
        if ($_POST['type'] == "line")
        {
            $array['cols'][] = array('type' => 'string');
            $array['cols'][] = array('type' => 'number');

            $temp = array();
            $array['row'][] = array('v' => (string) "20-01-13");
            $array['row'][] = array('v' => (int) 35);
            $array['row'][] = array('v' => (string) "21-01-13");
            $array['row'][] = array('v' => (int) 30);

        }
}
 
 虽然没有发生错误，但是折线图有点显示，但没有线，就好像数据是0.下面是如何显示图表的屏幕截图 
 
 
 以下是JSON内容的输出。 
 
{"cols":[{"type":"string"},{"type":"number"}],"row":[{"c":[{"v":"20-01-13"},{"v":22}]},{"c":[{"v":"21-01-13"},{"v":24}]},{"c":[{"v":"22-01-13"},{"v":27}]}]}
 
 感谢您的任何帮助，您可以提供。 
 
 更新我试图做@davidkonrad建议但我现在遇到了另一个问题。 我已经将行的定义更改为PHP数组的行，如下所示： 
 
    $array['cols'][] = array('type' => 'string');
    $array['cols'][] = array('type' => 'number');

    $array['rows'][] = array('c' => "20-01-13");
    $array['rows'][] = array('v' => 35);
    $array['rows'][] = array('c' => "21-01-13");
    $array['rows'][] = array('v' => 30);
 
 但是现在当图形加载时，我得到了Cannot read property '0' of undefined其中应该显示图形。 
 
 下面是如何生成JSON 
 
{"cols":[{"type":"string"},{"type":"number"}],"rows":[{"c":"20-01-13"},{"v":35},{"c":"21-01-13"},{"v":30}]}
 
 我看不到如何更改数组，使其与davidkonrad提供的JSON相匹配 

javaI am trying to create a line chart using the Google Chart API. I am trying to set the data using JSON for the datatable via a AJAX post. 
 
I have a version working for the pie chart but I can't find out how to do it for the line chart. 
 
Below is how I am creating the chart with the ajax post. 
 
function drawLineGraph()
             {
                 $.post("loadGraph.php",
                    {
                        type: "line"
                    },
                    function (result)
                    {
                        var data = new google.visualization.DataTable(result);
                        var options = {
                            title: "Line Graph Test"
                        };

                        var chart = new google.visualization.LineChart(document.getElementById("lineChart"));
                        chart.draw(data, options);
                    }, "json"
                );
             }
 
Below is the code for the loadGraph.php
 
print json_encode(test());

    function test()
    {
        $array = array();
        if ($_POST['type'] == "line")
        {
            $array['cols'][] = array('type' => 'string');
            $array['cols'][] = array('type' => 'number');

            $temp = array();
            $array['row'][] = array('v' => (string) "20-01-13");
            $array['row'][] = array('v' => (int) 35);
            $array['row'][] = array('v' => (string) "21-01-13");
            $array['row'][] = array('v' => (int) 30);

        }
}
 
Although no errors occur, the line chart is sort of displayed, but there is no line, as if the data is 0. Below is a screenshot of how the chart is being displayed
 
 
Below is the output of the JSON content.
 
{"cols":[{"type":"string"},{"type":"number"}],"row":[{"c":[{"v":"20-01-13"},{"v":22}]},{"c":[{"v":"21-01-13"},{"v":24}]},{"c":[{"v":"22-01-13"},{"v":27}]}]}
 
Thanks for any help you can provide.
 
UPDATE I have tried to do what @davidkonrad suggested but I am now getting a different problem. I have changed the definition of row to rows for the PHP array as follows:
 
    $array['cols'][] = array('type' => 'string');
    $array['cols'][] = array('type' => 'number');

    $array['rows'][] = array('c' => "20-01-13");
    $array['rows'][] = array('v' => 35);
    $array['rows'][] = array('c' => "21-01-13");
    $array['rows'][] = array('v' => 30);
 
But now when the graph loads I get Cannot read property '0' of undefined where the graph should be displayed. 
 
Below is how the JSON is now being generated
 
{"cols":[{"type":"string"},{"type":"number"}],"rows":[{"c":"20-01-13"},{"v":35},{"c":"21-01-13"},{"v":30}]}
 
I can't see how to change the array to make it match with the JSON that davidkonrad provided

原文：https://stackoverflow.com/questions/17327022