An API key is used by a lot of Web API to provide a form of access control. The key usually is linked to the identity of the API user as well as bundle of rights like a quota or areas of the APIs which are open for access to that key
Example::
<?php
// get the HTTP method, path and body of the request
$method = $_SERVER['REQUEST_METHOD'];
$request = explode('/', trim($_SERVER['PATH_INFO'],'/'));
$input = json_decode(file_get_contents('php://input'),true);
// connect to the mysql database
$link = mysqli_connect('localhost', 'root', 'root', 'myDB');
mysqli_set_charset($link,'utf8');
// retrieve the table and key from the path
$table = preg_replace('/[^a-z0-9_]+/i','',array_shift($request));
$key = array_shift($request)+0;
// escape the columns and values from the input object
$columns = preg_replace('/[^a-z0-9_]+/i','',array_keys($input));
$values = array_map(function ($value) use ($link) {
if ($value===null) return null;
return mysqli_real_escape_string($link,(string)$value);
},array_values($input));
// build the SET part of the SQL command
$set = '';
for ($i=0;$i<count($columns);$i++) {
$set.=($i>0?',':'').'`'.$columns[$i].'`=';
$set.=($values[$i]===null?'NULL':'"'.$values[$i].'"');
}
// create SQL based on HTTP method
switch ($method) {
case 'GET':
$sql = "select * from `myform`".($key?" WHERE id=$key":''); break;
case 'PUT':
$sql = "update `myform` set $set where id=$key"; break;
case 'POST':
$sql = "insert into `myform` set $set"; break;
case 'DELETE':
$sql = "delete `myform` where id=$key"; break;
}
// excecute SQL statement
$result = mysqli_query($link,$sql);
// die if SQL statement failed
if (!$result) {
http_response_code(404);
die(mysqli_error());
}
// print results, insert id or affected row count
if ($method == 'GET') {
if (!$key) echo '[';
for ($i=0;$i<mysqli_num_rows($result);$i++) {
echo ($i>0?',':'').json_encode(mysqli_fetch_object($result));
}
if (!$key) echo ']';
} elseif ($method == 'POST') {
echo mysqli_insert_id($link);
} else {
echo mysqli_affected_rows($link);
}
// close mysql connection
mysqli_close($link);
?>