Python &引用；django.db.utils.OperationalError：没有这样的表；在添加新应用程序时

我最近将

mycase

应用程序添加到了我更大的django项目中，但从那以后，我一直收到各种各样的数据库错误。如果有更多的信息会有帮助的话，只需回复一条评论，我不知道在这种情况下什么会有帮助。谢谢 回溯：

File "manage.py", line 22, in <module>
    main()
  File "manage.py", line 18, in main
    execute_from_command_line(sys.argv)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/core/management/__init__.py", line 401, in execute_from_command_line
    utility.execute()
  File "/opt/anaconda3/lib/python3.8/site-packages/django/core/management/__init__.py", line 395, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/core/management/base.py", line 330, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/core/management/base.py", line 368, in execute
    self.check()
  File "/opt/anaconda3/lib/python3.8/site-packages/django/core/management/base.py", line 392, in check
    all_issues = checks.run_checks(
  File "/opt/anaconda3/lib/python3.8/site-packages/django/core/checks/registry.py", line 70, in run_checks
    new_errors = check(app_configs=app_configs, databases=databases)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/core/checks/urls.py", line 40, in check_url_namespaces_unique
    all_namespaces = _load_all_namespaces(resolver)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/core/checks/urls.py", line 57, in _load_all_namespaces
    url_patterns = getattr(resolver, 'url_patterns', [])
  File "/opt/anaconda3/lib/python3.8/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/urls/resolvers.py", line 589, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/urls/resolvers.py", line 582, in urlconf_module
    return import_module(self.urlconf_name)
  File "/opt/anaconda3/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/Users/andrew/Desktop/Projects/purplerobotics/purplerobotics/urls.py", line 23, in <module>
    path('case/', include('mycase.urls'))
  File "/opt/anaconda3/lib/python3.8/site-packages/django/urls/conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "/opt/anaconda3/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 783, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/Users/andrew/Desktop/Projects/purplerobotics/mycase/urls.py", line 2, in <module>
    from . import views
  File "/Users/andrew/Desktop/Projects/purplerobotics/mycase/views.py", line 7, in <module>
    class CaseHome(ListView):
  File "/Users/andrew/Desktop/Projects/purplerobotics/mycase/views.py", line 10, in CaseHome
    total_price = CaseItem.objects.all().aggregate(total=Sum(F('Item_Price')*F('Item_Quantity')))['total']
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/models/query.py", line 398, in aggregate
    return query.get_aggregation(self.db, kwargs)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/models/sql/query.py", line 500, in get_aggregation
    result = compiler.execute_sql(SINGLE)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1156, in execute_sql
    cursor.execute(sql, params)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/backends/utils.py", line 98, in execute
    return super().execute(sql, params)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/backends/utils.py", line 66, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/backends/utils.py", line 75, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/backends/utils.py", line 84, in _execute
    return self.cursor.execute(sql, params)
  File "/opt/anaconda3/lib/python3.8/site-packages/django/db/backends/sqlite3/base.py", line 413, in execute
    return Database.Cursor.execute(self, query, params)
django.db.utils.OperationalError: no such table: mycase_caseitem

mycase models.py文件

from django.db import models
from django.urls import reverse
# Create your models here.

class CaseItem(models.Model):
    Item_Title = models.CharField(max_length=200)
    Item_Price = models.DecimalField(default=0, max_digits=10, decimal_places=2)
    Item_Quantity = models.DecimalField(default=0, max_digits=10, decimal_places=2)

    def __str__(self):
        return self.Item_Title + ' | ' + str(self.Item_Quantity) + ' * $' + str(self.Item_Price)

    def get_absolute_url(self):
        return reverse('home')

---

如果还有其他帮助的话，我很乐意得到它。

一旦您使用完模型，您就必须运行迁移-这将处理数据库进程，在本例中是创建表。 因此：

及

---

在CaseHome视图类中，您正在类主体中执行一个查询“total_price”，该查询在启动时执行，这将阻止您运行迁移，无论如何这是一种不好的做法。您需要将此查询移动到一个方法。我这样做了，但它仍然给我错误？很抱歉听到。我找到了此链接，它可能会有所帮助：：

from django.db import models
from django.urls import reverse
# Create your models here.

class CaseItem(models.Model):
    Item_Title = models.CharField(max_length=200)
    Item_Price = models.DecimalField(default=0, max_digits=10, decimal_places=2)
    Item_Quantity = models.DecimalField(default=0, max_digits=10, decimal_places=2)

    def __str__(self):
        return self.Item_Title + ' | ' + str(self.Item_Quantity) + ' * $' + str(self.Item_Price)

    def get_absolute_url(self):
        return reverse('home')

python manage.py makemigrations

python manage.py migrate