// @see https://drupal.stackexchange.com/a/99711/28091
// Using magic methods we can check if a specific property of the first item
// in the field has a value. $entity->field_name is equivalent to
// $entity->__get('field_name')). This may not be as safe as using
// ->get('field_name') but is useful. Read on...
// For simple text fields, booleans, etc. we can ask for ->value, for an
// entity reference we'd look at ->target_id. ->uri and ->title for a link.
// ->format and ->value for a long text field. Etc.
// Due to how __get('field_name') works, if the field doesn't exist on the
// entity, an InvalidArgumentException will not be thrown. If instead you
// use get('field_name') an exception would be thrown if field_name didn't
// exist on the entity. You would want to, in this case, check if the
// entity has a field with $entity->hasField('field_name');
// So, to see if a field exists and has a value, here are a few examples:
// Example 1 (top level entity already loaded):
if (isset($entity->field_name->target_id)) {
do_something();
}
// Example 2 (in a DSField plugin, load an entity then traverse it):
if (!isset($this->entity()->field_fullcalendar_subtitle->value)) {
do_something();
}
// If we need to loop through multiple items/values in a field (even if
// there is only one), you can either ask for an array using ->getValue(),
// or you can foreach the field using
// foreach ($entity->field_name as $field_item) {}. If you use this approach
// the items are objects. This is convenient for field types that have more
// methods. For example, you can get to the referenced taxonomy term via
// $field_item->entity->name->value, $field_item->entity->tid->value, etc.
// Example 3:
foreach ($entity->field_location as $field_item) {
$location_name = $field_item->entity->name->value;
}
// Here are some additional examples:
// Example 4:
$myentity->field_myref->entity->title->value
// Example 5:
$myentity->field_myref->referencedEntities()[0]->title->value
// Example 6:
foreach ($myentity->field_myref->referencedEntities() as $entity) {
$body_format = $entity->field_body->format;
$body_value = $entity->field_body->value;
}
