Using CURLOPT_HTTPHEADER with an Object - php

Question

When using PHP's curl API, if I accidentally use a string with the CURLOPT_HTTPHEADER curl option
curl_setopt($ch, CURLOPT_HTTPHEADER, 'User-Agent: php-curl');
PHP will scold me
Warning: curl_setopt(): You must pass either an object or an array with the CURLOPT_HTTPHEADER argument in /path/to/test.php on line 32
I know I can fix this using an array
$headers = [];
$headers[] = 'User-Agent: php-curl';
curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
However, the warning seems to indicate I could also be passing curl_setopt an object. Is this possible?
I've tried with both an stdClass and ArrayObject, but neither seems to work. Is this just a misleading warning message, or is there a way to use curl_setopt with an object?
Update Turns out I had a PHP extension installed that was blocking the standard behavior. ArrayObjects work fine in this function. I can't close or delete this question, so hopefully this warning will avoid confusion.

Answer 1

You need to pass an object that implements JsonSerializable.
class Testing implements JsonSerializable
{
protected $headers = [];
public function __construct($headers)
{
$this->headers = $headers;
}
public function jsonSerialize()
{
return $this->headers;
}
}
Then you can pass it to your CURLOPT_HTTPHEADER parameter:
$ch = curl_init();
curl_setopt($ch, CURLOPT_HTTPHEADER, new Testing(['User-Agent: php-curl']));