How do I trigger group membership was granted for a user - Group module

Question

I try to use group module in d8.

1. I created a new group type named test

2. I added 2 group as demo with admin is default group_membership.

3. in group 1 (name okok) I edited and added new user to group.

4. When I click the add member, the site redirect to another add form:

• I enter the user as normal.
• then click save button.

5. The result is User was added into that group.

---

So, What I wonder is how to know an user:

• Was added to a group.
• Was removed from a group.

Because I want to call another service every time that action/event was executed. For example, I want to log in to the watchdog like:

• "User A has been added into group X"
• "User B has been remove from group Y"

Is there any way to trigger that action/event in code.

Thanks for all your helps.

Answer 1

as @Jaypan suggested to me, I used hook_ENTITY_TYPE_insert() so my code is:

function hook_group_content_insert(GroupContentInterface $group_content) {
  if ($group_content->hasField('entity_id')
    && !$group_content->get('entity_id')->isEmpty()) {
    $users = $group_content->get('entity_id')->referencedEntities();
    $user = reset($users);
    if ($user instanceof UserInterface) {
      // Do your code here.
    }
  }
}