- Issue created by @erik.erskine
It would be nice to be able to use SingleValueTrait for fields of cardinalty 1, but that don't always have a value (like a non-required normal field).
At the moment you can't do that, and it's not obvious why.
Consider the following implementation:
singleComputeValue(EntityInterface $host_entity, ComputedFieldDefinitionWithValuePluginInterface $computed_field_definition): mixed {
if (/* some condition */) {
return 'some value';
}
else {
return NULL;
}
}
The trait produces these field values:
[
0 => NULL,
]
This leads to some cryptic error messages down the line:
Warning: array_flip(): Can only flip string and integer values, entry skipped in Drupal\Core\Entity\EntityStorageBase->loadMultiple() (line 278 of core/lib/Drupal/Core/Entity/EntityStorageBase.php).
The trait should probably produce this: (ie empty)
[].
Change SingleValueTrait as described. Also add something to the function's DocBlock to explain that returning NULL means "the field is empty".
Patch, test etc.
Active
4.0
Code