Question

我删除了整个数据库并重新创建了它，并从应用程序和项目的根文件夹（以及迁移文件夹）中删除了 pycache 文件夹。

我正在尝试从模型中创建数据库结构，如下所示： $ python manage.py makemigrations

这是我得到的错误，不幸的是到目前为止没有任何帮助我：

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/core/management/__init__.py", line 353, in execute_from_command_line
    utility.execute()
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/core/management/__init__.py", line 327, in execute
    django.setup()
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/apps/registry.py", line 108, in populate
    app_config.import_models(all_models)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/apps/config.py", line 202, in import_models
    self.models_module = import_module(models_module_name)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 986, in _gcd_import
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 958, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 673, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 662, in exec_module
  File "<frozen importlib._bootstrap>", line 222, in _call_with_frames_removed
  File "/Users/olegbelousov/dev/photobase/proto/models.py", line 100, in <module>
    class Photo(TimeStampedModel, SoftDeletableModel):
  File "/Users/olegbelousov/dev/photobase/proto/models.py", line 101, in Photo
    PHOTOGRAPHER_COUNT = Photographer.objects.count()
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/models/manager.py", line 122, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/models/query.py", line 371, in count
    return self.query.get_count(using=self.db)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/models/sql/query.py", line 483, in get_count
    number = obj.get_aggregation(using, ['__count'])['__count']
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/models/sql/query.py", line 464, in get_aggregation
    result = compiler.execute_sql(SINGLE)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/models/sql/compiler.py", line 848, in execute_sql
    cursor.execute(sql, params)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/backends/utils.py", line 79, in execute
    return super(CursorDebugWrapper, self).execute(sql, params)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/utils.py", line 95, in __exit__
    six.reraise(dj_exc_type, dj_exc_value, traceback)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/utils/six.py", line 685, in reraise
    raise value.with_traceback(tb)
  File "/Users/olegbelousov/.virtualenvs/photobasa/lib/python3.5/site-packages/django/db/backends/utils.py", line 64, in execute
    return self.cursor.execute(sql, params)
django.db.utils.ProgrammingError: relation "proto_photographer" does not exist
LINE 1: SELECT COUNT(*) AS "__count" FROM "proto_photographer"
                                          ^

Answer 1

makemigrations检查数据库以查看自上次迁移项目中每个应用程序以来是否发生了更改。为了使其正常运行，您的Django项目必须能够成功开始运行。如果缺少先前的表格，则不会发生这种情况。

运行python manage.py migrate以运行所有现有迁移，并使您的数据库进入上一组迁移所存储的状态。之后，您应该能够运行python manage.py makemigrations来创建新的迁移，然后再次使用python manage.py migrate。

删除数据库和迁移后，无法从模型（makemigrations）创建数据库

1 个答案: