问django.core.exceptions.ValidationError：[‘’本科生‘不是有效的UUID。’]

EN

undergrad_or_grad = models.OneToOneField(
    'StudentStatus', default="Undergraduate", on_delete=models.CASCADE)

from django.db import models
from django.contrib.auth.models import User
import uuid
from django.db.models.signals import post_save, post_delete    

class Profile(models.Model):
    user = models.OneToOneField(User, on_delete=models.CASCADE, null=True)
    profile_picture = models.ImageField(
        null=True, blank=True, upload_to='profiles/', default='profiles/defaultProfile.jpeg')
    username = models.CharField(
        max_length=200, null=True, blank=True, unique=True)
    name = models.CharField(max_length=200, null=True, blank=True)
    email = models.EmailField(max_length=1000, null=True, blank=True)
    undergrad_or_grad = models.OneToOneField(
        'StudentStatus', default="Undergraduate", on_delete=models.CASCADE)
    id = models.UUIDField(default=uuid.uuid4, unique=True,
                          primary_key=True, editable=False)

    def __str__(self):
        return str(self.username)


class StudentStatus(models.Model):
    STUDENT_TYPES = (
        ('undergrad', 'Undergraduate'),
        ('grad', 'Graduate'),
    )
    title = models.CharField(max_length=200, null=True,
                             blank=True, choices=STUDENT_TYPES)
    date_created = models.DateTimeField(auto_now_add=True)
    id = models.UUIDField(default=uuid.uuid4, unique=True,
                          primary_key=True, editable=False)

    def __str__(self):
        return str(self.title)

(env) PS D:\Django Projects\StudentArchive> python manage.py migrate       
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions, users
Running migrations:
  Applying users.0010_auto_20210815_0758...Traceback (most recent call last):
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\models\fields\__init__.py", line 2434, in to_python
    return uuid.UUID(**{input_form: value})
  File "c:\users\thatr\appdata\local\programs\python\python39\lib\uuid.py", line 177, in __init__
    raise ValueError('badly formed hexadecimal UUID string')
ValueError: badly formed hexadecimal UUID string

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "D:\Django Projects\StudentArchive\manage.py", line 22, in <module>
    main()
  File "D:\Django Projects\StudentArchive\manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\core\management\__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\core\management\__init__.py", line 413, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\core\management\base.py", line 354, in run_from_argv
    self.execute(*args, **cmd_options)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\core\management\base.py", line 398, in execute
    output = self.handle(*args, **options)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\core\management\base.py", line 89, in wrapped
    res = handle_func(*args, **kwargs)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\core\management\commands\migrate.py", line 244, in handle
    post_migrate_state = executor.migrate(
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\migrations\executor.py", line 117, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\migrations\executor.py", line 147, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\migrations\executor.py", line 227, in apply_migration
    state = migration.apply(state, schema_editor)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\migrations\migration.py", line 126, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\migrations\operations\fields.py", line 104, in database_forwards
    schema_editor.add_field(
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\backends\sqlite3\schema.py", line 330, in add_field
    self._remake_table(model, create_field=field)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\backends\sqlite3\schema.py", line 191, in _remake_table
    self.effective_default(create_field)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\backends\base\schema.py", line 324, in effective_default
    return field.get_db_prep_save(self._effective_default(field), self.connection)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\models\fields\related.py", line 971, in get_db_prep_save
    return self.target_field.get_db_prep_save(value, connection=connection)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\models\fields\__init__.py", line 842, in get_db_prep_save
    return self.get_db_prep_value(value, connection=connection, prepared=False)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\models\fields\__init__.py", line 2424, in get_db_prep_value
    value = self.to_python(value)
  File "D:\Django Projects\StudentArchive\env\lib\site-packages\django\db\models\fields\__init__.py", line 2436, in to_python
    raise exceptions.ValidationError(
django.core.exceptions.ValidationError: ['“Undergraduate” is not a valid UUID.']