Chart.js data array using PHP, MySQL. How to define datasource from JSON array?

Question

This is my first question. Kindly apologize for any errors.

I am trying to draw a chart using chart.js with PHP and MySQL data. The graph I intend to draw is a simple vertical barchart, birth_year vs number of people born. When I display the arrays $BIRTH_YEAR and $COUNTS, I could see the values. I was able to get to the point till json_encode($data_array). When I try to use this encoded array on javascript, I do not get any output, a blank page! Here is my code.

while ($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
$data[] = array(
    $row['BIRTH_YEAR']=>$row['counts'],
);
$BIRTH_YEAR[]=$row['BIRTH_YEAR'];
$COUNTS[]=$row['counts'];
}

// JSON arrays for labels and counts
$js_labels = json_encode($BIRTH_YEAR,true);
$js_cols = json_encode($COUNTS,true);


var barChartData = {
        labels : '<?php echo $js_labels; ?>',
                    datasets : [
            {
                fillColor : "rgba(220,220,220,0.5)",
                strokeColor : "rgba(220,220,220,1)",
                data : '<?php echo $js_cols; ?>'
            }

        ]
                   }

var myLine = new Chart(document.getElementById("canvas").getContext("2d")).Bar(barChartData);

I have included all other required HTML elements in my page. When I use the chart.js sample file I was able to see charts. The only issue is I am not sure how to include arrays in javascript data: part. Thanks in advance.

Solution

You could use $js_cols = json_encode($COUNTS,JSON_NUMERIC_CHECK);

and then

data : <?php echo print_r($js_cols,true); ?>