Pass JavaScript Array to PhpPresentation - php

Question

I am trying to use PhpPresentation to dinamically generate PowerPoint presentations with charts in PHP, using Google Analytics as data source.
I can make both processes independently (1. generating the pptx using a manually defined array of data and 2. generate an array in JavaScript with data from Google Analytics Core Reporting API). However, I am not able to combine both processes sucessfully (pass JavaScript's array and use it in PHP instead of my manually defined array).
1. generating the pptx using a manually defined array in php
If I use the following array as data source (as defined in PhpPresentation documentation), the PowerPoint is generated without problem:
$series2Data = array('20151201' => 266.1, '20151202' => 198.5, '20151203' => 271.8);
2. generate an array with data from Google Analytics Core Reporting API
The stringified array generated with JavaScript is:
[{"date":"20151201","avgSessionDuration":266.1},{"date":"20151202","avgSessionDuration":198.5},{"date":"20151203","avgSessionDuration":271.8}]
I am passing this array to the php that generates my PowerPoint:
<form method="post" id="theform" action="Sample_05_Chart.php">
<input type="hidden" id="markers" name="markers">
<button>Submit</button>
</form>
<script>
window.onload = function() {
var form = document.getElementById('theform');
form.addEventListener('submit', function(){
var markersField = document.getElementById('markers');
var markers = data2;
markersField.value = JSON.stringify(markers);
});
}
</script>
And in the PHP file I have added:
$markers = json_decode($_POST['markers']);
$series2Data = $markers;
However, the generated PowerPoint is corrupted, as I believe the array structure isn't what PhpPresentation expects.
My array's knowledge, however, is not so good in PHP as it is in JavaScript.
How could I transform an array, whose var_dump looks like
array(3) { [0]=> object(stdClass)#4 (2) { ["date"]=> string(8) "20151201" ["avgSessionDuration"]=> float(266.1) } [1]=> object(stdClass)#9 (2) { ["date"]=> string(8) "20151202" ["avgSessionDuration"]=> float(198.5) } [2]=> object(stdClass)#10 (2) { ["date"]=> string(8) "20151203" ["avgSessionDuration"]=> float(271.8) } }
into an array as described in point 1?

Answer 1

First of all, json_decode takes an optional second argument. First, the json string you wish to decode and second a boolean value which tells it whether or not to decode as an array of objects (stdClass) or as an associative array.
If you want the an associative array of the data posted, just use json_decode($markers, true).
However, the format you are asking for will not be given by this. So you need to massage the data some either in javascript or php.
Here's the php code to transform it:
$series2Data = [];
$markers = json_decode($_POST['markers'], true);
foreach ($markers as $marker) {
$series2Data[$marker['date']] = $marker['avgSessionDuration'];
}
Javascript:
function formatMarkersToData(markers) {
var series2Data = {};
for (var i = 0; i < markers.length; i++) {
var marker = markers[i];
series2Data[marker.date] = marker.avgSessionDuration;
}
return series2Data;
}
markersField.value = JSON.stringify(
formatMarkersToData(markers)
);
What both of these blocks of code do is loop over your data and set the index and value according to the required format of date => avgSessionDuration in the series2data variable. The javascript uses an object to allow for manually setting the key.
The above javascript code would then allow you to just use json_decode($_POST['markers'], true); to get the proper associative array for your $series2Data. Otherwise, you'll need the PHP code to do the massaging before passing it off to PhpPresentation.
It just depends on at what point you want the data transformed - on the server, or on the client. If this is at all confusing, please let me know.