Django: при печати QuerySet выдает ошибку

Question

У меня есть таблица (SavedSchedules) ниже в базе данных. В столбцах hall_n_time и schedule хранятся два списка python в виде строки.

+----+---------------+-------------+----------+
| id |   lecturer    | hall_n_time | schedule |
+----+---------------+-------------+----------+
|... |      ...      |     ...     |    ...   |
+----+---------------+-------------+----------+

У меня есть скрипт ниже views.py:

lec_name = User.objects.filter(username=request.session['logged_username']).values_list('lecturer_name', flat=True)
print(lec_name)

Это дает OUTPUT:

<QuerySet ['A. B. C. Watson']>

Но ОЖИДАЕМЫЙ ВЫХОД:

A. B. C. Watson

Затем я попробовал следующий скрипт:

lec_name = User.objects.filter(username=request.session['logged_username']).values_list('lecturer_name', flat=True)
schedule_data = SavedSchedules.objects.filter(lecturer=lec_name)
print(schedule_data)

Он выдает ОШИБКУ ниже, когда я его выполняю:

Traceback (most recent call last):
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\handlers\exception.py", line 34, in inner
    response = get_response(request)
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\handlers\base.py", line 115, in _get_response
    response = self.process_exception_by_middleware(e, request)
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\core\handlers\base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "D:\Web Projects\CIS_ALTG\altg\altg_app\views.py", line 497, in profile
    print(schedule_data)
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\query.py", line 252, in __repr__
    data = list(self[:REPR_OUTPUT_SIZE + 1])
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\query.py", line 276, in __iter__
    self._fetch_all()
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\query.py", line 1261, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\query.py", line 57, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\sql\compiler.py", line 1124, in execute_sql
    sql, params = self.as_sql()
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\sql\compiler.py", line 498, in as_sql
    where, w_params = self.compile(self.where) if self.where is not None else ("", [])
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\sql\compiler.py", line 415, in compile
    sql, params = node.as_sql(self, self.connection)
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\sql\where.py", line 81, in as_sql
    sql, params = compiler.compile(child)
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\sql\compiler.py", line 415, in compile
    sql, params = node.as_sql(self, self.connection)
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\lookups.py", line 177, in as_sql
    rhs_sql, rhs_params = self.process_rhs(compiler, connection)
  File "C:\Users\BhathiyaTK\AppData\Local\Programs\Python\Python37\lib\site-packages\django\db\models\lookups.py", line 270, in process_rhs
    'The QuerySet value for an exact lookup must be limited to '
ValueError: The QuerySet value for an exact lookup must be limited to one result using slicing.
[30/Apr/2020 17:26:37] "GET /profile/ HTTP/1.1" 500 122259

Я новичок в Django и понятия не имею, почему он дает такую ​​ошибку. Может кто-нибудь объяснить, почему это происходит и как решить эти проблемы? Я ценю вашу помощь. Я использую Python 3.7.4, Django 3.0.1