Python 我在Django更改许多字段时是否破坏了数据库？

所以我有一个外键字段，我需要把它转换成一个ManyToManyField。当我运行迁移时，它出现以下错误：

ValueError:无法将字段core_app.IndieTrack.contributors更改为 core_app.IndieTrack.contributors-它们是不兼容的类型（您可以 无法更改M2M字段或从M2M字段更改，或通过M2M上的=添加或删除 字段）

所以我说，“好吧，”然后我把它恢复到外键，想我会想出一个替代的解决方案。但是当我再次迁移（回到原始状态）时，它给了我同样的错误

现在我根本无法迁移任何更改。无论我做什么，我都会犯同样的错误

以下是整个回溯：

python3.4 manage.py makemigrations core_app              Migrations for 'core_app':
  0034_auto_20150521_0740.py:
    - Create model UserTrack
    - Remove field contributors from indietrack
    - Delete model IndieTrack
    - Alter field tracks on album
python3.4 manage.py migrate
Operations to perform:
  Apply all migrations: sessions, home, auth, admin, ipn, beat_store, blog, core    _app, contenttypes
Running migrations:
  Applying core_app.0024_auto_20150521_0634...Traceback (most recent call last):

Running migrations:
  Applying core_app.0024_auto_20150521_0634...Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/base.py", line 533, in handle
    return self.handle_noargs(**options)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/commands/syncdb.py", line 27, in handle_noargs
    call_command("migrate", **options)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/__init__.py", line 115, in call_command
    return klass.execute(*args, **defaults)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/core/management/commands/migrate.py", line 161, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/db/migrations/executor.py", line 68, in migrate
    self.apply_migration(migration, fake=fake)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/db/migrations/executor.py", line 102, in apply_migration
    migration.apply(project_state, schema_editor)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/db/migrations/migration.py", line 108, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/db/migrations/operations/fields.py", line 139, in database_forwards
    schema_editor.alter_field(from_model, from_field, to_field)
  File "/home/thephltr/webapps/who_pro/lib/python3.4/Django-1.7.7-py3.4.egg/django/db/backends/schema.py", line 454, in alter_field
    new_field,
ValueError: Cannot alter field core_app.IndieTrack.contributors into core_app.IndieTrack.contributors - they are not compatible types (you cannot alter to or from M2M fields, or add or remove through= on M2M fields)

我需要做一些改变。如有任何见解，将不胜感激

---

我使用的是PostgreSQL

如果您只更改了该字段，我建议您返回您的“迁移”文件夹，删除您尝试将其更改为多个字段后创建的字段。因为您已经创建了上述迁移，Django会按顺序运行它们，所以它会继续尝试运行它，因为您在此之后进行的迁移依赖于它，并且错误会不断出现。这是我为自己的理智所做的

---

如果您更改了其他字段，也许可以输入该迁移文件并删除与该字段相关的位

当您进行迁移时，是否会出现该错误？如果没有，那么

makemigrations

的结果是什么？makemigrations工作正常，没有错误。我会把这些东西添加到原始帖子中。听起来像我想要的。我在Migrations文件夹中，但是只有一堆py文件。我如何找到“迁移”呢？从最新的角度来看。但是，从您的回溯来看，有问题的文件是

core\u app.0024\u auto\u 20150521\u 0634

。因此，您可以删除该文件和随后创建的文件。同样，完成之后，如果数据库中没有内容，请删除该外键字段，并创建一个名称相同的多个外键字段。即使我从表存在之前返回到旧迁移，它也不允许我删除该表，也不接受该表的任何版本。我非常困惑和沮丧！是否有迁移保存在我看不见的地方，并且每次都在加载它们？我一直得到相同的值错误。解决方案是从应用程序文件夹中删除迁移文件。我刚刚从数据库中删除了迁移记录，但我不得不删除实际的迁移。哦，我不知道你在这么做，我在第一句话中写道，要转到迁移文件夹。但很高兴它成功了。

class IndieTrack(models.Model):
    duration = models.CharField(max_length=12, default='0:00')
    track_title = models.CharField(max_length=95)
    track_number = models.IntegerField(default=0)
    contributors = models.ForeignKey(Artist, null=True, blank=True)
    extra_info = models.TextField(null=True, blank=True)

    def __str__(self):
        return self.track_title