Internal Server Error: /api/v1/curriculum-units/all/invite/
Traceback (most recent call last):
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/core/handlers/exception.py", line 39, in inner
    response = get_response(request)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/core/handlers/base.py", line 187, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/core/handlers/base.py", line 185, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view
    return view_func(*args, **kwargs)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/rest_framework/viewsets.py", line 87, in view
    return self.dispatch(request, *args, **kwargs)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/rest_framework/views.py", line 474, in dispatch
    response = self.handle_exception(exc)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/rest_framework/views.py", line 434, in handle_exception
    self.raise_uncaught_exception(exc)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/rest_framework/views.py", line 471, in dispatch
    response = handler(request, *args, **kwargs)
  File "/Users/cryingjoker/actionProjects/academy2/academy/common/api/views.py", line 262, in invite_users
    receiver=new_user, token=default_token_generator.make_token(new_user))
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/query.py", line 399, in create
    obj.save(force_insert=True, using=self.db)
  File "/Users/cryingjoker/actionProjects/academy2/academy/features/notifications/models.py", line 93, in save
    super(Notification, self).save(*args, **kwargs)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/base.py", line 796, in save
    force_update=force_update, update_fields=update_fields)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/base.py", line 823, in save_base
    self._save_parents(cls, using, update_fields)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/base.py", line 848, in _save_parents
    self._save_table(cls=parent, using=using, update_fields=update_fields)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/base.py", line 908, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/base.py", line 947, in _do_insert
    using=using, raw=raw)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/query.py", line 1045, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/models/sql/compiler.py", line 1054, in execute_sql
    cursor.execute(sql, params)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/utils.py", line 94, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Users/cryingjoker/.virtualenvs/academy2.7/lib/python2.7/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
IntegrityError: null value in column "type_id" violates not-null constraint
DETAIL:  Failing row contains (5, 2017-01-13 21:53:38.812914+00, 2017-01-13 21:53:38.812944+00, f, null, 6, null, 32).