on_headers

Summary

A callable that is invoked when the HTTP headers of the response have been received but the body has not yet begun to download.

Types

• callable

Constant

GuzzleHttp\RequestOptions::ON_HEADERS

The callable accepts a Psr\Http\ResponseInterface object. If an exception is thrown by the callable, then the promise associated with the response will be rejected with a GuzzleHttp\Exception\RequestException that wraps the exception that was thrown.

You may need to know what headers and status codes were received before data can be written to the sink.

// Reject responses that are greater than 1024 bytes.
$client->request('GET', 'http://httpbin.org/stream/1024', [
    'on_headers' => function (ResponseInterface $response) {
        if ($response->getHeaderLine('Content-Length') > 1024) {
            throw new \Exception('The file is too big!');
        }
    }
]);

Note

When writing HTTP handlers, the on_headers function must be invoked before writing data to the body of the response.