Drupal 7: Hooks for entity references

Question

Is it possible to hook on changes of entity references? Let's say I have a <- b and b <- x -> a. when a <- b changes to d <- b I want also b <- x -> a to change to b <- x -> d

Answer 1

Where is the field at? My first inclination would be to use hook_entity_update. But you could catch all entities using: hook_field_update

http://api.drupal.org/api/drupal/modules%21field%21field.api.php/function/hook_field_update/7