Remove has_member function from application model

atst/models/application.py

@@ -51,10 +51,6 @@ class Application(
     def displayname(self):
         return self.name
 
-    def has_member(self, user_id):
-        user_ids = set(str(user.id) for user in self.users)
-        return str(user_id) in user_ids
-
     def __repr__(self):  # pragma: no cover
         return "<Application(name='{}', description='{}', portfolio='{}', id='{}')>".format(
             self.name, self.description, self.portfolio.name, self.id

atst/routes/applications/settings.py

@@ -45,8 +45,9 @@ def serialize_env_member_form_data(application):
 
 
 def check_users_are_in_application(user_ids, application):
+    existing_ids = [str(role.user_id) for role in application.roles]
     for user_id in user_ids:
-        if not application.has_member(user_id):
+        if not user_id in existing_ids:
             raise NotFoundError("application user", user_id)
     return True