Assigning a user to a case written in PHP.

assign_user.php

<?php

$json = json_encode(array(
  '_links' => array(
    'assigned_user' => array(
      'href' => '/api/v2/users/16096734',
      'class' => 'user'
    )
  )
));

echo($json);

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://site.desk.com/api/v2/cases/3012');
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "PATCH");
curl_setopt($ch, CURLOPT_USERPWD, "agent@example.com:SuperSecretPassword");
curl_setopt($ch, CURLOPT_POSTFIELDS, $json);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
  'Content-Type: application/json',
  'Content-Length: ' . strlen($json))
);

$result = curl_exec($ch);

curl_close($ch);

echo($result);