TypeError：预期的字符串或类似字节的对象-Django

Question

我已经通过nginx，gunicorn将Django应用程序部署到DigitalOcean服务器。今天，我想添加脚本models.DateTimeField(auto_now_add=True)来保存发送用户消息的日期，但是在迁移过程中（从ubuntu服务器上的github提取整个存储库之后），我遇到了以下错误。而且我想问题出在迁移文件中，但是不知道如何在服务器上操作它们以及如何安全地进行操作而不丢失任何数据。

错误：

Applying pragmatechapp.0004_auto_20200328_1036...Traceback (most recent call last):
  File "manage.py", line 21, in <module>
    main()
  File "manage.py", line 17, in main
    execute_from_command_line(sys.argv)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/core/management/base.py", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/core/management/base.py", line 364, in execute
    output = self.handle(*args, **options)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/core/management/base.py", line 83, in wrapped
    res = handle_func(*args, **kwargs)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/core/management/commands/migrate.py", line 234, in handle
    fake_initial=fake_initial,
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/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 "/home/kerimov/pragmatechproject/env/lib/python3.5/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 "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/migrations/executor.py", line 245, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/migrations/migration.py", line 124, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/migrations/operations/fields.py", line 112, in database_forwards
    field,
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 433, in add_field
    definition, params = self.column_sql(model, field, include_default=True)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 161, in column_sql
    default_value = self.effective_default(field)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/backends/base/schema.py", line 233, in effective_default
    return field.get_db_prep_save(self._effective_default(field), self.connection)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 793, in get_db_prep_save
    return self.get_db_prep_value(value, connection=connection, prepared=False)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 1435, in get_db_prep_value
    value = self.get_prep_value(value)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 1414, in get_prep_value
    value = super().get_prep_value(value)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 1274, in get_prep_value
    return self.to_python(value)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 1375, in to_python
    parsed = parse_datetime(value)
  File "/home/kerimov/pragmatechproject/env/lib/python3.5/site-packages/django/utils/dateparse.py", line 106, in parse_datetime
    match = datetime_re.match(value)
TypeError: expected string or bytes-like object

[注意：我应该很快解决这个问题，请知道答案的每个人都帮助我。我真的很沮丧和压力。

Answer 1

作为解决方案，我使用命令find . -path "*/migrations/{my_migration_names}.py" -not -name "__init__.py" -delete逐个删除迁移。要获取我所有迁移文件的名称，您应该运行python3 manage.py showmigrations命令。