Avoid warnings if $entity is not set

AFAIK, entity metadata getters should always get the entity as the first parameter. Eg:

/**
 * Gets the property just as it is set in the data.
 */
function entity_property_verbatim_get($data, array $options, $name, $type, $info) {

To fix these notices I create another patch that check the variable, because a Getter Callback always have a validation like on 'entity_property_verbatim_get'.

+++ b/source/deploy/modules/contrib/flag/flag.module
@@ -2622,24 +2622,29 @@ function flag_field_attach_rename_bundle($entity_type, $bundle_old, $bundle_new)
+  if (is_object($entity) && isset($property_info['flag_name'])) {

$entity should always be the entity. Please explain why this might be otherwise.

Joachim, this is done by default even inside entity_property_verbatim_get. It is a good codification practice and you shouldn't trust that entity_metadata_wrapper will always give you an object there.

In the example of this issue, the error was reproduced by using RESTWS to generate a users.json file, since it tries to load the properties of all users (including the "anonymous user" -> user 0).

If that's too much trouble, it's simple, just load user 0 with entity_metadata_wrapper and try to access its properties. You will see that for any of the core properties it won't return a notice, since they check if the property exist using empty() or isset().

For reference, please check the following core callbacks:
entity_metadata_user_get_properties
entity_metadata_node_get_properties
entity_property_verbatim_get
entity_property_verbatim_date_get

Works fine for me:

  $anon = user_load(0);
  dsm($anon);
  $wrapper = entity_metadata_wrapper('user', $anon);
  $flaggings = $wrapper->flag_bookmarks_flagged->value();
  dsm($flaggings);
  $flagged = $wrapper->flag_user_flag->value();
  dsm($flagged);

Please provide code that causes a problem!

  $wrapper = entity_metadata_wrapper('user', 0);
  $flagged = $wrapper->flag_sid->value();

Returns a notice on watchdog

Notice: Trying to get property of non-object in flag_properties_get_user_sid() (line 2683 of /home/fcaminada/Pfizer/Github/pfdigitalpf/source/deploy/modules/contrib/flag/flag.module).

Just like this issue's description.

So we have this:

  // Getter callbacks get an entity:
  $anon = user_load(0);
  $wrapper = entity_metadata_wrapper('user', $anon);
  // Getter callbacks do NOT get an entity:
  $wrapper = entity_metadata_wrapper('user', 0);

That's an inconsistent behaviour in Entity module, so the bug is there, not here.

Also, these callbacks clearly are meant to have an entity parameter and not a FALSE, which is what I get in the case when I pass in a user ID of 0. So again, this looks like a bug.

It would help if these callbacks were properly documented -- I made a start here: #2310981: callback documentation for entity metadata wrappers. Without documentation to say that $entity might not be an object, I'm going to say it's a bug in Entity module.