PHP array into google charts

i see you haven't found out how to do it after your first question, so i've made you a working example here, hope this helps you Dave :).

If you've got some questions about this, feel free to ask!

<?php 
//create array variable
$values = [];

//pushing some variables to the array so we can output something in this example.
array_push($values, array("year" => "2013", "newbalance" => "50"));
array_push($values, array("year" => "2014", "newbalance" => "90"));
array_push($values, array("year" => "2015", "newbalance" => "120"));

//counting the length of the array
$countArrayLength = count($values);

?>
<script type="text/javascript" src="https://www.google.com/jsapi"></script>
<script type="text/javascript">
google.load("visualization", "1", {packages:["corechart"]});
google.setOnLoadCallback(drawChart);

function drawChart() {

    var data = new google.visualization.DataTable();
    data.addColumn('string', 'Year');
    data.addColumn('number', 'Balance');

    data.addRows([

    <?php
    for($i=0;$i<$countArrayLength;$i++){
        echo "['" . $values[$i]['year'] . "'," . $values[$i]['newbalance'] . "],";
    } 
    ?>
    ]);

    var options = {
        title: 'My Savings',
        curveType: 'function',
        legend: { position: 'bottom' } 
    };

    var chart = new google.visualization.LineChart(document.getElementById('curve_chart'));
    chart.draw(data, options);
}
</script>

<div class="grid-container"> 
<div class="grid-100 grid-parent">
    <div id="curve_chart" style="width: 100%; height: auto"></div>
</div>   

</div>

I have dealt quite a bit with the Google Charts API recently and I have a few recommendations. The PHP code that you have written should largely work, but it does require that your Javascript code be embedded in a PHP page.

Maybe that is okay for your purposes, but I mostly recommend keeping your Javascript separate from your PHP. Some developers may be comfortable with one, but not the other, so mixing the two languages could become a maintenance issue. Now, that pretty much leaves you with using AJAX to retrieve your JSON charts data. This is a good approach, but I do not like the code that you featured in your question for a few reasons.

Firstly, the code uses async: false which will remove your user's control of the browser while the data is being fetched. In other words, the browser will appear to freeze until the data is returned from the AJAX request.

Also, I do not understand the whole .responseText convention. I understand what the code is accomplishing; I just fail to understand why the author chose that particular approach. Here is what I would do instead.

$.ajax({
    url: "test.php",
    dataType: "JSON",
    data: [any POST parameters that you need here],
    type: "POST",
    success: function(json) {
        var jsonData = JSON.parse(json); // jsonData will be a Javascript object or array.
        data.addRows(jsonData);
        drawChart();
    },
    error: function(jxqhr) {
        // Handle a bad AJAX call
    }
});

So how does this help your application overall? Well, in your server side code, you can handle any errors (i.e. bad user input) by responding to the AJAX call with a HTTP 500 error and the AJAX call can communicate the problem to your user. Furthermore, when your page loads, the rest of the page will continue loading while your AJAX call is off fetching data.

JS Fiddle

json_encode works just fine, you can put it in a variable like var grafica = <?php echo json_encode($grafica); ?> ; (look my example below) or just like you put it in your example, except that the only problem in it, is that you have double brackets, the ones inside jaso_encode($chart_arr) object and the externals data.addRows([ ... ]), that gives you [[...]] and generates and error, take off the brackets, try it like this:

 data.addRows(  
         <?php echo json_encode($chart_arr);?>  
           );

and not this

  data.addRows([  
     <?php echo json_encode($chart_arr);?>  
       ]);

I have included and example of how I am using it, be aware that in the documentation, (which in my opinion could be better) they placed the entire code in the <head> section because they have all the data there, but that may cause problems in real working examples, I only placed the CDN (Content Delivery Network) of google chart in the <head> and in the <body> all the Javascript code after the PHP code, not included in this example for clarity purposes, then the <div> but this last could go before the script tags. The order is important because you need to get the data first before constructing the graph.

I hope this helps.

<!DOCTYPE html>

    <head>

        <meta charset="utf-8"/>
        <script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>

    </head>


<body>

<script type="text/javascript">

      google.charts.load("current", {packages:["corechart"]});       
      google.charts.setOnLoadCallback(drawChart);

      function drawChart() {

        var data = new google.visualization.DataTable();
       data.addColumn('string', 'fecha'); // Implicit domain column.
       data.addColumn('number', 'peso'); // Implicit data column.
       data.addColumn({type:'string', role:'annotation'}); // columna para anotaciones
       data.addColumn({type:'string', role:'style'});  // comumna para estilo


    var grafica =  <?php    echo json_encode($grafica);        ?> ;   

       data.addRows(grafica);


        var options = {
        title:'Peso Total', width:600,height:400,
        colors: ['#C0C0C0'],
        curveType: 'function',
          legend: 'none',
          pointSize: 12,
          annotations: {
                textStyle: {
                  fontName: 'Times-Roman',
                  fontSize: 32,
                  color: '#99ff99',
                  opacity: 0.5,
                }

              }

        };

        var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
        chart.draw(data, options);
      }
    </script>






 <div id="chart_div" style="margin: 80px auto; width: 650px; height: 450px; border: 2px solid #4CAF50; border-radius: 20px; padding:5px; "></div>


</html>