Nothing displayed in Highchart Column - php

Question

I'm trying to display average grades for each individual assignment but I'm getting no luck displaying it within a Highchart Column. It displays just the legend and "where the graph should be".
I have my div <div id="container"></div> as well as the necessary SQL code:
$row=$db->prepare ("SELECT r.due_date as Due, m.module_name as Module, r.ass_name as Assignment, avg(amount) as Grade
from score s
INNER JOIN assignment r ON s.assignment_id = r.ass_id
INNER JOIN module m ON r.module_id = m.module_id
WHERE r.module_id = 7
GROUP BY r.due_date asc;");
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
var options = {
chart: {
renderTo: 'container',
type: 'line',
marginRight: 130,
marginBottom: 25
},
title: {
text: 'Revenue vs. Overhead',
x: -20 //center
},
subtitle: {
text: '',
x: -20
},
xAxis: {
categories: []
},
yAxis: {
title: {
text: 'Amount'
},
plotLines: [{
value: 0,
width: 1,
color: '#808080'
}]
},
tooltip: {
formatter: function() {
return '<b>'+ this.series.name +'</b><br/>'+
this.x +': '+ this.y;
}
},
legend: {
layout: 'vertical',
align: 'right',
verticalAlign: 'top',
x: -10,
y: 100,
borderWidth: 0
},
series: []
}
$.getJSON("avg_grades.json", function(json) {
options.xAxis.categories = json[0]['Assignments'];
options.series[0] = json[1];
chart = new Highcharts.Chart(options);
});
});
</script>
<script src="http://code.highcharts.com/highcharts.js"></script>
<script src="http://code.highcharts.com/modules/exporting.js"></script>
<div id="container"></div>
<?php
$db=new PDO('mysql:dbname=attendance_database;host=localhost;','user','password');
$row=$db->prepare ("SELECT r.due_date as Due, m.module_name as Module, r.ass_name as Assignment, avg(amount) as Grade
from score s
INNER JOIN assignment r ON s.assignment_id = r.ass_id
INNER JOIN module m ON r.module_id = m.module_id
WHERE r.module_id = 7
GROUP BY r.due_date asc;");
$row2=$db->prepare ("SELECT r.due_date as Due, m.module_name as Module, r.ass_name as Assignment, avg(amount) as Grade
from score s
INNER JOIN assignment r ON s.assignment_id = r.ass_id
INNER JOIN module m ON r.module_id = m.module_id
WHERE r.module_id = 7
GROUP BY r.due_date asc;");
$row3=$db->prepare ("SELECT r.due_date as Due, m.module_name as Module, r.ass_name as Assignment, avg(amount) as Grade
from score s
INNER JOIN assignment r ON s.assignment_id = r.ass_id
INNER JOIN module m ON r.module_id = m.module_id
WHERE r.module_id = 7
GROUP BY r.due_date asc;");
$row->execute();
###############################
$json_data=array();
$json_data['name'] = 'Assignments';
foreach($row as $rec)
{
$json_data['value'][]=$rec['Assignment'];
}
##########################
$json_data2=array();
$json_data2['name'] = 'Grade';
$row2->execute();
foreach($row2 as $rec2)
{
$json_data2['value'][]=$rec2['Grade'];
}
$result = array();
array_push($result,$json_data);
array_push($result,$json_data2);
$fp = fopen("avg_grades.json", "w");
fwrite($fp, json_encode($result));
fclose($fp);
echo json_encode($result);
?>
Expected outcome
Highcharts.chart('container', {
chart: {
type: 'column'
},
title: {
text: 'Monthly Average Rainfall'
},
subtitle: {
text: 'Source: WorldClimate.com'
},
xAxis: {
categories: [
'Find Hidden Data',
'Google Hacking',
'Caine Testing',
'Penetration Testing',
'FA 2'
],
crosshair: true
},
yAxis: {
min: 0,
title: {
text: 'Grades %'
}
},
tooltip: {
headerFormat: '<span style="font-size:10px">{point.key}</span><table>',
pointFormat: '<tr><td style="color:{series.color};padding:0">{series.name}: </td>' +
'<td style="padding:0"><b>{point.y:.1f} %</b></td></tr>',
footerFormat: '</table>',
shared: true,
useHTML: true
},
plotOptions: {
column: {
pointPadding: 0.2,
borderWidth: 0
}
},
series: [{
name: 'Avg Grade',
data: [99, 70,80, 47.5, 70, 40]
}]
});
<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/modules/exporting.js"></script>
<div id="container" style="min-width: 310px; height: 400px; margin: 0 auto"></div>
Actual outcome

Answer 1

Actual problem is in php $json_data2;
Instead of
$json_data2=array();
$json_data2['name'] = 'Grade';
$row2->execute();
foreach($row2 as $rec2)
{
$json_data2['value'][]=$rec2['Grade'];
}
it should be
$json_data2=array();
$json_data2['name'] = 'Grade';
$row2->execute();
foreach($row2 as $rec2)
{
$json_data2['value'][]=intval($rec2['Grade']); /*intval()*/
}
This will result in correct JSON string with array of numbers instead of array of string
final output [{"name":"Assignments","value":["Find Hidden Data","Google Hacking","Caine Testing","Penetration Testing","FA 2"]},{"name":"Grade","value":[99,70,80,47.5,70,40]}]
In your current JSON string,
this is demonstration to show when array of string ["99", "70","80", "47.5", "70", "40"] is converted to array of numbers [99, 70,80, 47.5, 70, 40] then only chart works as desired
var data = [{
"name": "Assignments",
"value": ["Find Hidden Data", "Google Hacking", "Caine Testing", "Penetration Testing", "FA 2"]
}, {
"name": "Grade",
"value": ["99", "70", "80", "47.5", "70", "40"]
}]
/*problem is here in second object value having array of string*/
var categories, datasN
for (var i = 0; i < data.length; i++) {
if (data[i].name == "Assignments") {
categories = data[i].value
}
if (data[i].name == "Grade") {
datasN = data[i].value.map(Number) /*converting string array to number array*/
}
}
Highcharts.chart('container', {
chart: {
type: 'column'
},
title: {
text: 'Monthly Average Rainfall'
},
subtitle: {
text: 'Source: WorldClimate.com'
},
xAxis: {
categories: categories,
crosshair: true
},
yAxis: {
min: 0,
title: {
text: 'Grades %'
}
},
tooltip: {
headerFormat: '<span style="font-size:10px">{point.key}</span><table>',
pointFormat: '<tr><td style="color:{series.color};padding:0">{series.name}: </td>' +
'<td style="padding:0"><b>{point.y:.1f} %</b></td></tr>',
footerFormat: '</table>',
shared: true,
useHTML: true
},
plotOptions: {
column: {
pointPadding: 0.2,
borderWidth: 0
}
},
series: [{
name: 'Avg Grade',
data: datasN
}]
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/modules/exporting.js"></script>
<div id="container" style="min-width: 310px; height: 400px; margin: 0 auto"></div>
Hope this gives you enough explanation