Okay, I read a bunch of questions on StackOverflow but didn't seem to solve my problem.
I have a php file like this one:
<?php
require "config.php";
try {
$conn = new PDO("mysql:host=" . DB_SERVER . ";dbname=" . DB_NAME, DB_USERNAME, DB_PASSWORD);
}
catch(PDOException $e) {
die("Database connection could not be established.");
}
$conn->exec("SET NAMES UTF8");
$sql = "SELECT result.year, SUM(result.grade) AS year_total_points
FROM (
SELECT *
FROM students AS s
INNER JOIN points AS p
ON s.fn = p.student_fn
) result
GROUP BY result.year
ORDER BY year_total_points DESC";
$query = $conn->query($sql);
if($query->rowCount() > 0) {
$data = array (
"years" => [],
"years_total_points" => [],
);
while ($row = $query->fetch(PDO::FETCH_ASSOC)) {
$data['years'][] = $row['year'];
$data['years_total_points'][] = $row['year_total_points'];
}
echo json_encode($data);
}
else {
echo mysql_error();
}
$conn = null;
?>
Long story short I make a query to the database and get a table with column year and column year_total_points. I want to store the data in an associative array so I can pass it to the js file. Because I later in the js file need an array of all years as strings and an array of all points also as strings, I decided to store them in an associative array. But I think that json_encode doesn't encode it as it should because executing the following code:
function success(data){
var barChartData = {
labels : data["years"],
datasets : [
{
fillColor : "rgba(151,187,205,0.5)",
strokeColor : "rgba(151,187,205,0.8)",
highlightFill : "rgba(151,187,205,0.75)",
highlightStroke : "rgba(151,187,205,1)",
data : data["years_total_points"]
}
]
}
var ctx = document.getElementById("myChart").getContext("2d");
window.myBar = new Chart(ctx).Bar(barChartData, {
responsive : true
});
}
function error(){
alert('Error!');
}
window.onload = function(){
$.ajax({url: "http://localhost/year_comparison.php"}).done(success).error(error);
}
it says that data["years"] is undefined and I would expect it to be something like ["2011", "2012", "2013"]. Everything with the query is ok because when I added alert(data); I got a result {"years":["2011"],"years_total_points":["85.98"]}. But alert(data["years"]) says undefined. Any help to solve this issue would be greatly appreciated.