EntityReferenceItem::isEmpty() will return FALSE if the referenced item was deleted.

Hi Friends,

Here is the patch.

I see where you're going but I think this change would somewhat contradict the interface description:

* Determines whether the data structure is empty.

The structure is not empty if it has target_id defined, and I actually find it strange that it checks entity at all.

A value currently does exist in the target_id property, if it is a valid reference at that point in time is a separate concern for the caller, no?

I find it easier to reconcile this statement

$field->isEmpty() === FALSE &&
$field->target_id === 123 &&
$field->getValue() == [['target_id' => 123] &&
$field->entity === NULL

compared to this statement

$field->isEmpty() === TRUE &&
$field->target_id === 123 &&
$field->getValue() == [['target_id' => 123] &&
$field->entity === NULL

If this patch is applied $field->isEmpty() takes a performance hit when entities do exist and it'd be cheaper to do empty($field->target_id) directly when it's expected to not be set, but that's not understood as well by my IDE and has a higher cognitive load when reading compared to .

Practically this change affects when I want to be able to tell the difference between a reference existing and if it is not currently valid, but there's also the interface "contract" to consider. It looks to me like it's not concerned about what a contained value actually means, just if it exists.

EntityReferenceItem::isEmpty() returning FALSE for deleted references is correct because the entity reference field in core does not enforce data integrity. If you need this functionality, there are two options:

1) Use a module like https://www.drupal.org/project/entity_reference_integrity or https://www.drupal.org/project/erri to prevent that would prevent references from being deleted

2) Write a custom module (I couldn't find any existing one in contrib) that would cascade the deletion of an entity to all the entity reference fields that use it as a target