Hide Admin Toolbar in iFrame

Question

Is it somehow possible within Drupal 8 to hide the Admin Toolbar when the site is loaded within an iFrame? Like e.g. passing an argument? :-)

I thought about using some sort of preprocess on the page that is getting rendered within the iFrame, but this will not work since the html is cached by Drupal. Also I thought about doing it within Javascript, but I do not want to include a javascript file on every page but default.

Maybe someone knows a hook_() which will allow me to manipulate the css but is not getting cached?

Answer 1

I would use a similar approach as @Hudri and access the site as https://www.mysite.com?is_iframe=true.

Then, add a class to the body tag if the request option is there:

/**
 * Implements hook_preprocess_HOOK().
 */
function MYMODULE_preprocess_html(&$variables) {
  $is_iframe = \Drupal::request()->query->get('is_iframe');
  if ($is_iframe === 'true') {
    $variables['attributes']['class'][] = 'hide-admin-toolbar';
  }
}

If I remember correctly, Drupal will regenerate the HTML when you access https://www.mysite.com?is_iframe=true vs https://www.mysite.com.

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References:

• https://drupal.stackexchange.com/a/207046/56157
• https://drupal.stackexchange.com/a/210379/56157

Answer 2

This should be doable with a cache context:

Drupal core already provides a cache context
url.query_args
which can be used for your query parameter, e.g. an URL
https://www.mysite.com?is_iframe=true
would be a cache context
\Drupal::service('cache_context.url.query_args')->getContext('is_iframe');

AFAIK the cache_context url.query_args is already enabled by default in Drupal core, so you only need to add this cache context to the render array in an appropriate preprocess function.

Note that cache contexts generally do not work with Internal Page Cache module!

For production you should finetune this with a more specific, custom cache-context url.query_args:my_query_param to limit unnecessary cache contexts (dumb bots could trigger a gazillion cache context calculations otherwise)