'NoneType'對象在Django遷移中沒有屬性'is_relation'錯誤

Question

我試圖從Heroku上的Django現有模型中刪除一些字段，因此我運行了make遷移，然后遷移了命令，好像遷移成功了。

之后，我發現缺少一個字段，因此我自己創建了下一個遷移文件，並將依賴項放到了先前自動生成的遷移文件中。 當我運行它時，會出現如下錯誤：

~ $ python manage.py migrate
Operations to perform:
  Apply all migrations: API, admin, auth, authtoken, contenttypes, sessions
Running migrations:
  Applying API.0007_timezoneremoval...Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
    utility.execute()
  File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/__init__.py", line 356, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/base.py", line 330, in execute
    output = self.handle(*args, **options)
  File "/app/.heroku/python/lib/python3.6/site-packages/django/core/management/commands/migrate.py", line 204, in handle
    fake_initial=fake_initial,
  File "/app/.heroku/python/lib/python3.6/site-packages/django/db/migrations/executor.py", line 115, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "/app/.heroku/python/lib/python3.6/site-packages/django/db/migrations/executor.py", line 145, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "/app/.heroku/python/lib/python3.6/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/app/.heroku/python/lib/python3.6/site-packages/django/db/migrations/migration.py", line 119, in apply
    operation.state_forwards(self.app_label, project_state)
  File "/app/.heroku/python/lib/python3.6/site-packages/django/db/migrations/operations/fields.py", line 150, in state_forwards
    delay = not old_field.is_relation
AttributeError: 'NoneType' object has no attribute 'is_relation'

該錯誤可能是由何處引起的？ 謝謝

Answer 1

你可以去到migrate文件夾，刪除所有.py除了文件__init__.py 。

之后，運行：

python manage.py makemigrations