django - URL 配置的 Django 迁移问题

Question

当我们开始我们的 Django 项目时，我们创建了迁移并进行了迁移，但是现在，当我们想要更改数据模型并运行时，makemigrations我们会收到一个很大的错误消息（见下文）。回溯消息后，我发现当我path('', include('quizarchiv.urls')),在运行迁移时评论谎言时，一切都很好。所以我想我有两个问题：

1. 为什么这种解决方法有效（至少对于创建迁移）？
2. 我们如何调整我们的项目以再次使用迁移？

这是我们的 models.py 的一部分（它相当长）：

class questioncategory(models.Model):
    cat_id = models.AutoField(primary_key=True)
    cat_name = models.CharField(max_length=255, unique=True)


class question(models.Model):
    q_id = models.AutoField(primary_key=True)
    q_title = models.CharField(max_length=255, unique=True)
    q_question = models.CharField(max_length=1000)
    f_kat = models.ForeignKey(questioncategory, on_delete=models.PROTECT)

---

完整的错误信息：

COMPUTER:FOLDER USERNAME$ python3 manage.py migrate
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/backends/sqlite3/base.py", line 383, in execute
    return Database.Cursor.execute(self, query, params)
sqlite3.OperationalError: no such table: questioncategory

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

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 "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/management/base.py", line 323, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/management/base.py", line 361, in execute
    self.check()
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/management/base.py", line 390, in check
    include_deployment_checks=include_deployment_checks,
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/management/commands/migrate.py", line 65, in _run_checks
    issues.extend(super()._run_checks(**kwargs))
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/management/base.py", line 377, in _run_checks
    return checks.run_checks(**kwargs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/checks/registry.py", line 72, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/checks/urls.py", line 40, in check_url_namespaces_unique
    all_namespaces = _load_all_namespaces(resolver)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/core/checks/urls.py", line 57, in _load_all_namespaces
    url_patterns = getattr(resolver, 'url_patterns', [])
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/utils/functional.py", line 80, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/urls/resolvers.py", line 571, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/utils/functional.py", line 80, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/urls/resolvers.py", line 564, in urlconf_module
    return import_module(self.urlconf_name)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/Users/USERNAME/PROJECTPATH/web/web/urls.py", line 22, in <module>
    path('', include('quiz.urls')),
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/urls/conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/Users/USERNAME/PROJECTPATH/web/quizarchiv/urls.py", line 2, in <module>
    from . import views
  File "/Users/USERNAME/PROJECTPATH/web/quizarchiv/views.py", line 20, in <module>
    from .forms import ErstelleFrage, ErstelleSession, ErstelleAsset, ErstelleHinweis, ErstelleTeam, ErstelleKategorie
  File "/Users/USERNAME/PROJECTPATH/web/quizarchiv/forms.py", line 8, in <module>
    class ErstelleFrage(forms.Form):
  File "/Users/USERNAME/PROJECTPATH/web/quizarchiv/forms.py", line 12, in ErstelleFrage
    f_kategorie = forms.ChoiceField(choices=[(kat.kategorie_id, kat.k_name) for kat in FrageKategorie.objects.all()], label="Kategorie")
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/models/query.py", line 274, in __iter__
    self._fetch_all()
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/models/query.py", line 1242, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/models/query.py", line 55, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1097, in execute_sql
    cursor.execute(sql, params)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/backends/utils.py", line 99, in execute
    return super().execute(sql, params)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/backends/utils.py", line 67, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/backends/utils.py", line 76, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/site-packages/django/db/backends/sqlite3/base.py", line 383, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such table: questioncategory

标签： djangodjango-models

Answer 1

问题不在于您的网址包含。问题是在您的 ErstelleFrage 表单中，您正在执行类级别的查询，该查询在导入时执行；只是包含是导致该表单被导入的东西。

您永远不应该在字段或表单定义中进行这样的查询。在这种特殊情况下，您应该使用带有查询集的 ModelChoiceField，而不是带有明确选择的选项集的 ChoiceField。