Learn some tips about Drupal 8

Learning a new system usually means learning about its little quirks. Drupal 8 has its fair share of quirks. Here are some quick tips that I have learned in the past few months working on my first Drupal 8 project.

addExpression

Suppose you need to get the last time an item in a table was edited. You can build a dynamic query and, instead of using fields(), you'd use addExpression() like so:

$query->addExpression('MAX(mod_date)', 'col_alias');

Now you will get the highest timestamp.

$timestamp = $query->execute()->fetchField();

Differences between $entity->field_name and $entity->get('field_name')

$entity->field_name will return null if the field does not exist while $entity->get('field_name') will throw an Exception. Sometimes you'll want one behavior over another so keep that in mind.

Adding a class to a item list elements

I almost went mad looking for an answer until I dived into the code and learned about #wrapper_attributes. Just add this to your item list render array and you're good to go. It will apply those attributes to each <li> tag within your item list.

appendItem

If you need to add a value to a multivalue field in an entity, you can use appendItem() to get the job done.

$entity->field_multivalue->appendItem($some_other_entity_id);

Over the coming weeks, I or any of my fellow developers here at Rootstack will be posting quick tips for other developers new to Drupal 8. I'm sure you will learn a thing or two or, at the very least, we will save you from a mild headache.