php-json-to-csv.php

<?php

function hwk_the_json_to_csv($json, $delimiter = ';'){
    echo hwk_get_json_to_csv($json, $delimiter);
}

function hwk_get_json_to_csv($json, $delimiter = ';'){
    $data = json_decode($json, true);
    if(!is_array($data) || empty($data))
        return;
    
    $ouput = fopen('php://output', 'w');
    $firstline = false;
    ob_start();
    
    foreach($data as $line){
        if(empty($firstline)){
            $firstline = array_keys($line);
            fputcsv($ouput, $firstline, $delimiter);
            
            $firstline = array_flip($firstline);
        }
        
        fputcsv($ouput, array_merge($firstline, $line), $delimiter);
    }
    
    return ob_get_clean();
}