Drupal's cache system is robust, feature full and extensible. It can be used to cache small blocks of rendered output or the results of more complex calculations. The cache can be stored in a for the page request, in a database or in a different cache system.
From the pages of 'crazy things you can do with Drupal 8' comes this idea that I recently had to implement on a site. This was on a site that had implemented translations, but they needed something a little extra. The central idea was that if you visited a page on the site in a particular language, and that language didn't exist, then to try and give the user a similar language.
For a long time the drupal_set_message() function has been a mainstay of Drupal development. You can use this function to print a message or an error response to a user. This is useful to do as it can be done almost anywhere before the final page rendering functions and will be printed into the same area of a Drupal page.
When developing sites in Drupal 7 I found the hook_init() hook was a good way of quickly testing certain things in code. By adding little blocks of code it was possible to build complex SQL queries, inspect internal configuration, or even test complex node interactions.
The Shield module prevents access to a Drupal site by putting a Apache authentication system across the entire website. This means that to access the site you need a username and password.
This is useful in a number of different situations, but I use it most for protecting dev and staging sites from access. It's not the most complex authentication system in the world, but it's enough to prevent the embarrassment caused by having staging sites being spidered by search engines.
To find out if the current user is anonymous use the following.
\Drupal::currentUser()->isAnonymous();
This can be used as part of an if statement like this:
To get the currently selected language on a Drupal 8 site you need to run the following.
$language = \Drupal::languageManager()->getCurrentLanguage()->getId();
This will return the 2 character ISO language code for the language. So for English this would be "en".
To get the language name instead of the language code use this.
$language = \Drupal::languageManager()->getCurrentLanguage()->getName();When creating re-usable theme templates in Drupal 8 it's quite easy to include that template by using the following snippet.
{% include directory ~ '/templates/parts/footer.html.twig' %}
This assumes that your footer.html.twig template file is kept in the same theme as the template you are working on. It's also good practice to add the template part to a directory called 'parts' or 'components' to separate them from the normal Drupal templates.