Separate webhook create form from event type field addition

byceps/blueprints/admin/webhook/forms.py

@@ -21,23 +21,38 @@ class CreateForm(LocalizedForm):
     url = StringField(lazy_gettext('URL'), [InputRequired()])
 
 
-def assemble_create_form_with_events(
+def assemble_create_form(event_names: Set[str]) -> Type[LocalizedForm]:
+    return _extend_form_for_event_types(CreateForm, event_names)
+
+
+def _extend_form_for_event_types(
+    form_class,
     event_names: Set[str],
 ) -> Type[LocalizedForm]:
-    """Dynamically add a checkbox per event type to the creation form."""
+    """Dynamically add a checkbox per event type to the form."""
+
+    class FormWithEventTypes(form_class):
+        pass
 
-    class FormWithEvents(CreateForm):
+    _add_event_field_getter_to_form(FormWithEventTypes)
+    _add_event_fields_to_form(FormWithEventTypes, event_names)
 
-        def get_field_for_event_name(self, event_name: str):
-            field_name = _create_event_field_name(event_name)
-            return getattr(self, field_name)
+    return FormWithEventTypes
 
+
+def _add_event_field_getter_to_form(form_class) -> None:
+    def get_field_for_event_name(self, event_name: str):
+        field_name = _create_event_field_name(event_name)
+        return getattr(self, field_name)
+
+    form_class.get_field_for_event_name = get_field_for_event_name
+
+
+def _add_event_fields_to_form(form_class, event_names: Set[str]) -> None:
     for event_name in event_names:
         field_name = _create_event_field_name(event_name)
         field = BooleanField()
-        setattr(FormWithEvents, field_name, field)
-
-    return FormWithEvents
+        setattr(form_class, field_name, field)
 
 
 def _create_event_field_name(event_name: str) -> str:

byceps/blueprints/admin/webhook/views.py

@@ -20,7 +20,7 @@
 from ....util.views import permission_required, redirect_to, respond_no_content
 
 from .authorization import WebhookPermission
-from .forms import assemble_create_form_with_events
+from .forms import assemble_create_form
 
 
 blueprint = create_blueprint('webhook_admin', __name__)
@@ -52,9 +52,9 @@ def index():
 def create_form(erroneous_form=None):
     """Show form to create a webhook."""
     event_names = WEBHOOK_EVENT_NAMES
-    CreateFormWithEvents = assemble_create_form_with_events(event_names)
+    CreateForm = assemble_create_form(event_names)
 
-    form = erroneous_form if erroneous_form else CreateFormWithEvents()
+    form = erroneous_form if erroneous_form else CreateForm()
 
     return {
         'form': form,
@@ -67,9 +67,9 @@ def create_form(erroneous_form=None):
 def create():
     """Create a webhook."""
     event_names = WEBHOOK_EVENT_NAMES
-    CreateFormWithEvents = assemble_create_form_with_events(event_names)
+    CreateForm = assemble_create_form(event_names)
 
-    form = CreateFormWithEvents(request.form)
+    form = CreateForm(request.form)
 
     if not form.validate():
         return create_form(form)