How can I add custom headers to an ElementAPI response?

Question

I need to add the a custom header to the ElementAPI endpoints I setup but I want to avoid editing the source of the plugin. What is the best way to go about this?

The ElementAPI plugin returns some default headers by using:

JsonHelper::sendJsonHeaders()

To quickly achieve what I needed I added the following to the ElementApiControllor.php:

HeaderHelper::setHeader(['Surrogate-Control: max-age=300'])

This works for now but I'd love to learn how to extend existing plugins that don't have any documented hooks with my own if it is possible.

Answer 1

You can do this by assigning your endpoint(s) to a function:

return [
    'endpoints' => [
        'my-endpoint' => function() {
            HeaderHelper::setHeader(['Surrogate-Control: max-age=300']);

            return [
                // ...
            ];
        }
    ]
];

UPDATE

Alternatively as of v1.2, you can do it from a separate plugin using the onBeforeSendData event:

public function init()
{
    craft()->on('elementApi.onBeforeSendData', function(Event $event) {
        HeaderHelper::setHeader(['Surrogate-Control: max-age=300']);
    });
}

Answer 2

In case anyone finds this in a Google search, this is how you'd do it in Craft 3, if, say, you wanted to add an Expires header:

$response = Craft::$app->getResponse();
$response->headers->set('Expires', gmdate('D, d M Y H:i:s \G\M\T', strtotime("+1 month")));

Yii2 Responses