Converting a returned PHP file to XML - php

Question

I am looking for a way to convert a PHP file that I retrieve from a website into XML format using a PHP script.
The returned file I get is:
{ "days": [
{"reference":"13L6-A67-1", "dayinit":"4","hourinit":"9"},
{"reference":"13L6-A67-1", "dayinit":"5","hourinit":"9"} ]}
Is there anyway I could convert this to an XML file like this:
<?xml version="1.0"?>
<days>
<day>
<lesson>
<reference>13L6-A67-1</reference>
<hourinit>9</hourinit>
</lesson>
</day>
<day>
<lesson>
<reference>13L6-A67-1</reference>
<hourinit>9</hourinit>
</lesson>
</day>
</days>
Preferably so it groups data based on the "dayinit".

Answer 1

You can convert the data to an array and loop through it:
$test_array = json_decode('{ "days": [
{"reference":"13L6-A67-1", "dayinit":"4","hourinit":"9"},
{"reference":"13L6-A67-1", "dayinit":"5","hourinit":"9"} ]}',true);
$xml = '<?xml version="1.0"?>';
$xml .= '<days>';
foreach($test_array['days'] as $day) {
$xml .= '<day>';
$xml .= '<lesson>';
$xml .= '<reference>';
$xml .= $day['reference'];
$xml .= '</reference>';
$xml .= '<dayinit>';
$xml .= $day['reference'];
$xml .= '</reference>';
$xml .= '</dayinit>';
$xml .= $day['hourinit'];
$xml .= '</hourinit>';
$xml .= '</lesson>';
$xml .= '</day>';
}
$xml .= '</days>';

Answer 2

What you retrieve is content written in JSON. You could try to use PHP native functions to transform your content. The following example is rough draw how you could approach your solution.
First, fetch and decode JSON (documentation):
$json = '...'; // JSON content
$data = json_decode($json, true);
Then, use the XML Parser (documentation) to render your $data into XML:
// Something like
$xml_parser = xml_parser_create();
xml_parse($xml_parser, $data);