Headers

Both request and response messages contain HTTP headers.

Accessing Headers

You can check if a request or response has a specific header using the hasHeader() method.

use GuzzleHttp\Psr7;
$request = new Psr7\Request('GET', '/', ['X-Foo' => 'bar']);
if ($request->hasHeader('X-Foo')) {
    echo 'It is there';
}

You can retrieve all the header values as an array of strings using getHeader().

$request->getHeader('X-Foo'); // ['bar']
// Retrieving a missing header returns an empty array.
$request->getHeader('X-Bar'); // []

You can iterate over the headers of a message using the getHeaders() method.

foreach ($request->getHeaders() as $name => $values) {
    echo $name . ': ' . implode(', ', $values) . "\r\n";
}

Complex Headers

Some headers contain additional key value pair information. For example, Link headers contain a link and several key value pairs:

<http://foo.com>; rel="thing"; type="image/jpeg"

Guzzle provides a convenience feature that can be used to parse these types of headers:

use GuzzleHttp\Psr7;
$request = new Psr7\Request('GET', '/', [
    'Link' => '<http:/.../front.jpeg>; rel="front"; type="image/jpeg"'
]);
$parsed = Psr7\parse_header($request->getHeader('Link'));
var_export($parsed);

Will output:

array (
  0 =>
  array (
    0 => '<http:/.../front.jpeg>',
    'rel' => 'front',
    'type' => 'image/jpeg',
  ),
)

The result contains a hash of key value pairs. Header values that have no key (i.e., the link) are indexed numerically while headers parts that form a key value pair are added as a key value pair.