How do I show the site slogan?

Question

I am trying to set up my first web site using Drupal 8 an Bootstrap. Unfortunately I wasn't able to show the site's slogan in Bootstrap theme. The slogan is set in /admin/config/system/site-information but is not shown. So I thought by my self, it may not be printed in page.html.twig and tried to include it there. It's preamble says:

 * Available variables:
 * Site identity:
 * - front_page: The URL of the front page. Use this instead of base_path when
 *   linking to the front page. This includes the language domain or prefix.
 * - logo: The url of the logo image, as defined in theme settings.
 * - site_name: The name of the site. This is empty when displaying the site
 *   name has been disabled in the theme settings.
 * - site_slogan: The slogan of the site. This is empty when displaying the site
 *   slogan has been disabled in theme settings.

So I tried to print the slogan by including

{{ site_slogan }}

But this does not have any effect at all.

Can somebody please tell me, how to print the site slogan in Bootstrap?

[The lack of documentation and stable modules and themes should have been considered a release blocker for Drupal 8, but this is only my opinion and off topic here!]

Answer 1

After some desperate digging I found the solution (come on Drupal guys, don't be shy, give us some documentation!): Go to /admin/structure/block and click the 'configure' button of the block named 'Site branding'. There you can choose which parts of site branding are shown.

Answer 2

This is how to get the site slogan to pring in your theme page template without using the branding block (bootstrap or not):

function THEME_preprocess_page(&$vars) {

    $site_config = \Drupal::config('system.site');

    $vars['site_name'] = $site_config->get('name');
    $vars['site_slogan'] = $site_config->get('slogan');

}