[Solved] How to hook into Commerce after payment complete - Drupal
The most effective way to intercept or modify user data during registration is through the following hooks: Usage Note Runs before the user is saved.
Inside presave , always call $user->isNew() to ensure your code only runs during initial registration rather than every time a profile is updated. drupal-8-user-register-hook
If you need to stop registration based on custom business logic (e.g., checking an external blacklist), use a custom validation handler via hook_form_alter .
For cleaner, decoupled code, consider Symfony Event Subscribers if you are using the Hook Event Dispatcher module. [Solved] How to hook into Commerce after payment
Use this to add custom fields or validation logic (e.g., matching a secondary database). 💻 Code Example: hook_user_presave
This is the standard approach to identify a vs. an existing user being updated. an existing user being updated
Do you need help on the registration form, or are you looking to redirect users after they sign up?