javascript - Array to string conversion while using canvas js in yii2

Question

I am trying to load a chart on my index page in yii2 project. Below is my code

<?PHP

$dataPoints1 = array(
array("label"=> "2010", "y"=> 36.12),
array("label"=> "2011", "y"=> 34.87),
array("label"=> "2012", "y"=> 40.30),
array("label"=> "2013", "y"=> 35.30),
array("label"=> "2014", "y"=> 39.50),
array("label"=> "2015", "y"=> 50.82),
array("label"=> "2016", "y"=> 74.70)
);
$dataPoints2 = array(
array("label"=> "2010", "y"=> 64.61),
array("label"=> "2011", "y"=> 70.55),
array("label"=> "2012", "y"=> 72.50),
array("label"=> "2013", "y"=> 81.30),
array("label"=> "2014", "y"=> 63.60),
array("label"=> "2015", "y"=> 69.38),
array("label"=> "2016", "y"=> 98.70)
);
?>

My JS

<?PHP
$script = <<< JS
window.onload = function () {
var chart = new CanvasJS.Chart("chartContainer1", {
animationEnabled: true,
theme: "light2",
title:{
    text: "Average Amount Spent on Real and Artificial X-Mas Trees in U.S."
},
legend:{
    cursor: "pointer",
    verticalAlign: "center",
    horizontalAlign: "right",
    itemclick: toggleDataSeries
},
data: [{
    type: "column",
    name: "Real Trees",
    indexLabel: "{y}",
    yValueFormatString: "$#0.##",
    showInLegend: true
    dataPoints: <?php echo json_encode($dataPoints1, JSON_NUMERIC_CHECK); ?>
},{
    type: "column",
    name: "Artificial Trees",
    indexLabel: "{y}",
    yValueFormatString: "$#0.##",
    showInLegend: true,
    dataPoints: <?php echo json_encode($dataPoints2, JSON_NUMERIC_CHECK); ?>
}]
});
chart.render();

function toggleDataSeries(e){
if (typeof(e.dataSeries.visible) === "undefined" || e.dataSeries.visible) {
    e.dataSeries.visible = false;
}
else{
    e.dataSeries.visible = true;
}
chart.render();
}
}

JS;
$this->registerJs($script);
?>

When I run my code I am getting below error

Array to string conversion

This error comes at dataPoints: <?php echo json_encode($dataPoints1, JSON_NUMERIC_CHECK); ?>

How can I rid of this error? Any help would hi highly appreciated

Answer 1

You should encode the php array to json outside the heredoc and supply the output to the javascript part, and you dont use the php tags but use curly braces {} to parse values from the variable inside the heredoc.

See below it should work correctly

<?PHP
$dataPoints1 = json_encode($dataPoints1, JSON_NUMERIC_CHECK);
$dataPoints2 = json_encode($dataPoints1, JSON_NUMERIC_CHECK);

$script = <<< JS
window.onload = function () {
var chart = new CanvasJS.Chart("chartContainer1", {
animationEnabled: true,
theme: "light2",
title:{
    text: "Average Amount Spent on Real and Artificial X-Mas Trees in U.S."
},
legend:{
    cursor: "pointer",
    verticalAlign: "center",
    horizontalAlign: "right",
    itemclick: toggleDataSeries
},
data: [{
    type: "column",
    name: "Real Trees",
    indexLabel: "{y}",
    yValueFormatString: "$#0.##",
    showInLegend: true
    dataPoints: {$dataPoints1}
},{
    type: "column",
    name: "Artificial Trees",
    indexLabel: "{y}",
    yValueFormatString: "$#0.##",
    showInLegend: true,
    dataPoints: {$dataPoints2}
}]
});
chart.render();

function toggleDataSeries(e){
if (typeof(e.dataSeries.visible) === "undefined" || e.dataSeries.visible) {
    e.dataSeries.visible = false;
}
else{
    e.dataSeries.visible = true;
}
chart.render();
}
}

JS;
$this->registerJs($script);
?>