如何正确地将php mysql数据传递给ChartJs

Question

我希望能够使用ChartJs生成条形图和饼图。我使用php和mysql来获取数据。我想要制作的条形图是一张图表，显示男生或女生的学生数量以及学生总数。下面是我多么希望的结果出现一个例子：

它可能不完全一样，但我觉得它给一个想法。我与我的代码有关的问题似乎并不明白，因为我是ChartJs的新手，只是尝试了一下，因为morris.js没有得到完全支持。这里是我的代码的外观：

的Html

<div class="box box-success"> 
     <div class="box box-header with-border"> 
      <h3 class="box-title">Student Chart</h3> 
      <div class="box-tools pull-right"> 
      <button type="button" class="btn btn-box-tool" data-widget="collapse"><i class="fa fa-minus"></i> 
      </button> 
      <button type="button" class="btn btn-box-tool" data-widget="remove"><i class="fa fa-times"></i></button> 
      </div> 
      <div class="box-body"> 
      <canvas id="mycanvas" style="height:230px;"></canvas> 
      </div> 
     </div> 

脚本：

$.ajax({ 
     url: 'data.php', 
     type: 'GET', 
     success:function(data){ 
     console.log(data); 

     var male = []; 
     var female = []; 

     for(var count in data){ 
      male.push(data[count].male); 
      female.push(data[count].female); 
     } 

     var chartdata = { 
      labels: male, 
      datasets: [ 
       { 
       label: 'Student Gender', 
       backgroundColor: 'rgba(200, 200, 200, 0.75)', 
       borderColor: 'rgba(200, 200, 200, 0.75)', 
       hoverbackgroundColor: 'rgba(200, 200, 200, 1)', 
       hoverborderColor: 'rgba(200, 200, 200, 1)', 
       data:female 
       } 
      ] 
     }; 

     var ctx = $('#mycanvas'); 

     var barGraph = new Chart(ctx, { 
      type:'bar', 
      data: chartdata 
     }); 
     }, 
     error:function(data){ 
     console.log(data); 
     } 
    }); 

data.php

$query = "SELECT 
      SUM(CASE WHEN gender = 'Male' THEN 1 ELSE 0 END) as Male, 
      SUM(CASE WHEN gender = 'Female' THEN 1 ELSE 0 END) as Female 
      FROM students"; 

$output = array(); 

if ($result = mysqli_query($connection, $query)) { 
    # code... 
    foreach ($result as $row) { 
     # code... 
     $output[] = $row; 
    } 
} else { 
    die("There was a problem". mysqli_error($connection)); 
} 

echo json_encode($output); 

下面是我从控制台得到的结果：

[{“Male”： “5”，“女”：“2”}]

将意识到如何使它更好的建议，也为饼图做同样的事情。

基于我所做的事，这是我的表是如何显示：

注意请忽略照片上的频率。

Answer 1

建议您将您的sql查询更改为以下内容。

$query = "select gender,count(gender) as count from students group by gender"; 
$output = array(); 

if ($result = mysqli_query($connection, $query)) { 
    # code... 
    foreach ($result as $row) { 
     # code... 
     $output[] = $row; 
    } 
} else { 
    die("There was a problem". mysqli_error($connection)); 
} 

echo json_encode($output); 

脚本：

$.ajax({ 
     url: 'data.php', 
     type: 'GET', 
     success:function(data){ 
     console.log(data); 

     var gender = []; 
     var sum = []; 

     for(var count in data){ 
      gender.push(data[count].gender); 
      sum.push(data[count].total); 
     } 

     var chartdata = { 
      labels: gender, 
      datasets: [ 
       { 
       label: 'Student Gender', 
       backgroundColor: 'rgba(200, 200, 200, 0.75)', 
       borderColor: 'rgba(200, 200, 200, 0.75)', 
       hoverbackgroundColor: 'rgba(200, 200, 200, 1)', 
       hoverborderColor: 'rgba(200, 200, 200, 1)', 
       data:sum 
       } 
      ] 
     }; 

     var ctx = $('#mycanvas'); 

     var barGraph = new Chart(ctx, { 
      type:'bar', 
      data: chartdata 
     }); 
     }, 
     error:function(data){ 
     console.log(data); 
     } 
    }); 

Answer 2

我意识到，问题出在我的脚本。非常感谢@milan kumar帮助查询。缺少的是我发送给ajax的数据类型的规范。我所要做的只是在成功函数之前添加值为'json'的dataType，并且它完美地工作。这是代码应该是什么样子：

脚本：

$.ajax({ 
     url: 'data.php', 
     type: 'GET', 
     // this was what I needed to make it work. 
     dataType: 'json', 
     success:function(data){ 

     var gender = []; 
     var sum = []; 

     for(var i in data){ 
      gender.push(data[i].gender); 
      sum.push(data[i].total); 
     } 

     var ChartData = { 
      labels: ['Student Gender'], 
      datasets: [ 
       { 
       label: gender[0], 
       fillColor: "rgba(210, 214, 222, 1)", 
       strokeColor: "rgba(210, 214, 222, 1)", 
       pointColor: "rgba(210, 214, 222, 1)", 
       pointStrokeColor: "#c1c7d1", 
       pointHighlightFill: "#fff", 
       pointHighlightStroke: "rgba(220,220,220,1)", 
       data:sum[0] 
       }, 
       { 
       label: gender[1], 
       fillColor: "rgba(60,141,188,0.9)", 
       strokeColor: "rgba(60,141,188,0.8)", 
       pointColor: "#3b8bba", 
       pointStrokeColor: "rgba(60,141,188,1)", 
       pointHighlightFill: "#fff", 
       pointHighlightStroke: "rgba(60,141,188,1)", 
       data:sum[1] 
       } 
      ] 
     }; 
     }); 

我增加了一些可选属性来美化我的图表。