Add signals to intercept regform field processing

CHANGES.rst

@@ -19,6 +19,14 @@ Bugfixes
 - Only show the warning about draft mode in a conference if it actually has any
   contributions or timetable entries
 
+Internal Changes
+^^^^^^^^^^^^^^^^
+
+- Add ``registration_form_wtform_created`` signal and send form data in
+  ``registration_created`` and ``registration_updated`` signals (:pr:`4642`,
+  thanks :user:`omegak`)
+
+
 Version 2.3
 -----------
 

indico/core/signals/event/registration.py

@@ -30,18 +30,29 @@
 
 registration_created = _signals.signal('registration-created', """
 Called when a new registration has been created. The `sender` is the `Registration` object.
+The `data` kwarg contains the form data used to populate the registration fields.
 The `management` kwarg is set to `True` if the registration was created from the event management area.
 """)
 
 registration_updated = _signals.signal('registration-updated', """
 Called when a registration has been updated. The `sender` is the `Registration` object.
+The `data` kwarg contains the form data used to populate the registration fields.
 The `management` kwarg is set to `True` if the registration was updated from the event management area.
 """)
 
 registration_deleted = _signals.signal('registration-deleted', """
 Called when a registration is removed. The `sender` is the `Registration` object.
 """)
 
+registration_form_wtform_created = _signals.signal('registration_form_wtform_created', """
+Called when a the wtform is created for rendering/processing a registration form.
+The sender is the `RegistrationForm` object. The generated WTForm class is
+passed in the `wtform_cls` kwarg and it may be modified. The `registration`
+kwarg contains a `Registration` object when called from registration edit
+endpoints. The `management` kwarg is set to `True` if the registration form is
+rendered/processed from the event management area.
+""")
+
 registration_form_created = _signals.signal('registration-form-created', """
 Called when a new registration form is created. The `sender` is the
 `RegistrationForm` object.

indico/modules/events/registration/util.py

@@ -161,6 +161,8 @@ def validate_email(self, field):
 
         field_impl = form_item.field_impl
         setattr(RegistrationFormWTF, form_item.html_field_name, field_impl.create_wtf_field())
+    signals.event.registration_form_wtform_created.send(regform, registration=registration, management=management,
+                                                        wtform_cls=RegistrationFormWTF)
 
     RegistrationFormWTF.modified_registration = registration
     return RegistrationFormWTF
@@ -235,7 +237,7 @@ def create_registration(regform, data, invitation=None, management=False, notify
         invitation.registration = registration
     registration.sync_state(_skip_moderation=skip_moderation)
     db.session.flush()
-    signals.event.registration_created.send(registration, management=management)
+    signals.event.registration_created.send(registration, management=management, data=data)
     notify_registration_creation(registration, notify_user)
     logger.info('New registration %s by %s', registration, user)
     registration.log(EventLogRealm.management if management else EventLogRealm.participants,
@@ -286,7 +288,7 @@ def modify_registration(registration, data, management=False, notify_user=True):
                         old_price, registration.price)
     if personal_data_changes:
         signals.event.registration_personal_data_modified.send(registration, change=personal_data_changes)
-    signals.event.registration_updated.send(registration, management=management)
+    signals.event.registration_updated.send(registration, management=management, data=data)
     notify_registration_modification(registration, notify_user)
     logger.info('Registration %s modified by %s', registration, session.user)
     registration.log(EventLogRealm.management if management else EventLogRealm.participants,