PHP script converting XML to CSV with column headers returning blank on some headers and rows

my full XML is below which is named user.xml:

<?xml version="1.0" encoding="utf-8"?>
<users>
                <user id='1'>
                                <user_name>John</user_name>
                                <user_lastname>Doe</user_lastname>
                                <previous_requisitions>
                                                <requisition_code>X321</requisition_code>
                                                <requisition_code>Y321</requisition_code>
                                                <requisition_code>Z321</requisition_code>
                                </previous_requisitions>
                                <user_requisition>
                                                <requisition_code>X123</requisition_code>
                                                <requisition_title>Ssr Dev 1</requisition_title>
                                                <requisition_relocation>10~20%</requisition_relocation>
                                </user_requisition>
                </user>
                <user id='2'>
                                <user_name>James</user_name>
                                <user_lastname>Smith</user_lastname>
                                <previous_requisitions>
                                                <requisition_code>X222</requisition_code>
                                                <requisition_code>Y222</requisition_code>
                                                <requisition_code>Z222</requisition_code>
                                </previous_requisitions>
                                <user_requisition>
                                                <requisition_code>Y123</requisition_code>
                                                <requisition_title>Sr Dev 1</requisition_title>
                                                <requisition_relocation>20~30%</requisition_relocation>
                                </user_requisition>
                </user>
                <user id='3'>
                                <user_name>Jess</user_name>
                                <user_lastname>Ssej</user_lastname>
                                <previous_requisitions>
                                                <requisition_code>X111</requisition_code>
                                                <requisition_code>Y111</requisition_code>
                                                <requisition_code>Z111</requisition_code>
                                </previous_requisitions>
                                <user_requisition>
                                                <requisition_code>Z123</requisition_code>
                                                <requisition_title>Jr Dev 2</requisition_title>
                                                <requisition_relocation>0~10%</requisition_relocation>
                                </user_requisition>
                </user>
</users>

since not very good with XML and with the help of online resources and stackoverflow; was able to create this PHP script:

<?php
$file='user.xml';
if (file_exists($file)) {
    $xml = simplexml_load_file($file);
    $f = fopen('user.csv', 'w');
    // array to hold the field names
    $headers = array(); 
    // loop through the first set of fields to get names
    foreach ($xml->user->children() as $field) { 
        // put the field name into array
        $headers[] = $field->getName(); 
    }
    // print headers to CSV
    fputcsv($f, $headers, ',', '"');
    foreach ($xml->user as $users) {
        fputcsv($f, get_object_vars($users), ',', '"');
    }
    fclose($f);
}
?>

when i run the PHP script, the file is written but with some issues:

1. not all headers are written.


2. not all data are written


3. first column is populated with "Array"

see below for screenshot of the result(open in excel):

QUESTIONS:

1. 
   

   since it appears that the $headers = array(); is not looping properly. any fix on the PHP script to show all headers and the data from the XML properly?

   
   


2. 
   

   i only need the following child nodes to be exported to CSV, so these 6 will also be the headers:

   
   

   user_id,

   
   

   user_name,

   
   

   user_lastname,

   
   

   user_requisition_code,

   
   

   user_requisition_title,

   
   

   user_requisition_relocation,

   
   

pls direct me how i can make the script "selective" in which omitting or not to include other child nodes from the XML like:

previous_requisitions

requisition_code

thanks a lot for the help and happy new year!

sidenote: would be sticking with opensource scripting hoping no one will answer with suggestion to use a proprietary software.