Best practice for getting field values of entity chains

Question

I really would like to make this if/else field value check just a little bit more sexy.

What's Best Practice for dealing with nested functions chains to get entity field values (check if they exist / check if they are not empty)

 if($entity->hasField('field_intro_teaser_image_media_')){
      $media_field = $entity->field_intro_teaser_image_media_;

      if($media_field->entity){
        $media_field_entity = $media_field->entity;

        if($media_field_entity->hasField('field_media_image')){
          $media_field_entity_image = $media_field_entity->field_media_image;

          if($media_field_entity_image){
            $media_field_entity_image_entity = $media_field_entity_image->entity;

            if($media_field_entity_image_entity){
              $media_field_entity_image_entity_uri = $media_field_entity_image->entity->getFileUri();

              if($media_field_entity_image_entity_uri){

                // ... yay we got the damn uri!

              }

            }
          }
        }
      }
    }

The one liner would be:

$media_field = $entity->field_intro_teaser_image_media_->entity->field_media_image->entity->getFileUri();



  

Answer 1

When you access fields by magic methods, you don't actually have to check for their existence by using hasField() method.:

$entity->field_that_does_not_exist->entity; // NULL.
$entity->get('field_that_does_not_exist'); // Exception.
$entity->get('field_that_does_not_exist')->entity; // Exception.

Using $entity->field_intro_teaser_image_media_->entity is sufficient in this case, if the field does not exist, the expression will be simply NULL, without any errors.

But of course you still have to check if referenced ->entity is not NULL. PHP 8.0 Null-safe operator may be a way to do it, as suggested by Clive.

$media_field = $entity
  ->field_intro_teaser_image_media_
  ->entity
  ?->field_media_image
  ->entity
  ?->getFileUri();

In case of using Null-safe operator, it will be probably faster to access entity fields by ->get(), to avoid additional logic.

$media_field = $entity
  ->get('field_intro_teaser_image_media_')
  ?->entity
  ?->get('field_media_image')
  ?->entity
  ?->getFileUri();

Answer 2

Assuming you've built the chain correctly, you can do it as follows:

$media_field = NULL;
try {
  $media_field = $entity->field_intro_teaser_image_media_->entity->field_media_image->entity->getFileUri();
}
catch (\Exception $e) {
  watchdog_exception('Media retrieval');
}

if (!is_null($media_field)) {
  // Do stuff.
}