Question

我重新安装了使用background_tasks的django应用。如果我删除了使用background_task的模型，那么我就能做到

python manage.py makemigrations

但是，如果我保留它们，则会出现表丢失的异常：

"mydb.background_task doesn't exist"

我见过其他遇到此问题的人，但我尝试了每个建议： -删除所有迁移文件 -删除sqlite3转储文件 -卸载django和django-background-tasks -确保我的机器即使在virtualenv之外也没有安装这两个软件包 -我尝试删除virtualenv并重新安装所有内容。

我已经尝试了所有这些事情，并且python manage.py makemigrations仍然给我该异常。但是，没有别的。

Django==2.1.5
django-background-tasks==1.2.0
django-compat==1.0.15
django-mysql==3.2.0

p.s：我正在使用Cloud SQL，我不知道这是否会影响任何事情，我不这么认为。 mysql同样的问题

编辑：添加跟踪

Traceback (most recent call last):
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/backends/mysql/base.py", line 71, in execute
    return self.cursor.execute(query, args)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/MySQLdb/cursors.py", line 198, in execute
    res = self._query(query)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/MySQLdb/cursors.py", line 304, in _query
    db.query(q)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/MySQLdb/connections.py", line 217, in query
    _mysql.connection.query(self, query)
MySQLdb._exceptions.ProgrammingError: (1146, "Table 'zynqdb_dev.background_task' doesn't exist")

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

Traceback (most recent call last):
  File "manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/management/__init__.py", line 381, in execute_from_command_line
    utility.execute()
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/management/__init__.py", line 375, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/management/base.py", line 316, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/management/base.py", line 350, in execute
    self.check()
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/management/base.py", line 379, in check
    include_deployment_checks=include_deployment_checks,
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/management/base.py", line 366, in _run_checks
    return checks.run_checks(**kwargs)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/checks/registry.py", line 71, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/checks/urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/core/checks/urls.py", line 23, in check_resolver
    return check_method()
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/urls/resolvers.py", line 396, in check
    for pattern in self.url_patterns:
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/urls/resolvers.py", line 533, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/utils/functional.py", line 37, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/urls/resolvers.py", line 526, in urlconf_module
    return import_module(self.urlconf_name)
  File "/Users/cottrell/tessel/venv/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/cottrell/tessel/tesselapp/tesselapp/urls.py", line 49, in <module>
    one_time_setup_background(priority=10)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/background_task/tasks.py", line 296, in __call__
    remove_existing_tasks)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/background_task/tasks.py", line 239, in schedule
    task.save()
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/background_task/models.py", line 315, in save
    return super(Task, self).save(*arg, **kw)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/models/base.py", line 718, in save
    force_update=force_update, update_fields=update_fields)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/models/base.py", line 748, in save_base
    updated = self._save_table(raw, cls, force_insert, force_update, using, update_fields)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/models/base.py", line 831, in _save_table
    result = self._do_insert(cls._base_manager, using, fields, update_pk, raw)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/models/base.py", line 869, in _do_insert
    using=using, raw=raw)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/models/manager.py", line 82, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/models/query.py", line 1136, in _insert
    return query.get_compiler(using=using).execute_sql(return_id)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/models/sql/compiler.py", line 1289, in execute_sql
    cursor.execute(sql, params)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 100, in execute
    return super().execute(sql, params)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/utils.py", line 89, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/backends/utils.py", line 85, in _execute
    return self.cursor.execute(sql, params)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/django/db/backends/mysql/base.py", line 71, in execute
    return self.cursor.execute(query, args)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/MySQLdb/cursors.py", line 198, in execute
    res = self._query(query)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/MySQLdb/cursors.py", line 304, in _query
    db.query(q)
  File "/Users/cottrell/tessel/venv/lib/python3.7/site-packages/MySQLdb/connections.py", line 217, in query
    _mysql.connection.query(self, query)
django.db.utils.ProgrammingError: (1146, "Table 'zynqdb_dev.background_task' doesn't exist")

我也已经尝试过：

find . -path "*/migrations/*.pyc"  -delete
find . -path "*/migrations/*.py" -not -name "__init__.py" -delete

我尝试重新安装和卸载。

此外，如果我执行python manage.py showmigrations，也会发生相同的错误。

这是模型的一部分，如果我注释掉@background，它将起作用，但是使用@background，它将不起作用。

def one_time_setup():
    if settings.SENTRY_TOKEN:
        sentry_sdk.init(
            settings.SENTRY_TOKEN,
            integrations=[DjangoIntegration()]
        )


#@background()
def one_time_setup_background():
    one_time_setup()


# Do one-time setup in django app, and background with high priority.
one_time_setup()
one_time_setup_background()

Answer 1

库中似乎有问题，请参见https://github.com/arteria/django-background-tasks/issues/204。您可能需要暂时删除代码以迁移数据库。

Answer 2

听起来您没有删除每个pycache文件夹的内容，这意味着Django仍将尝试引用不存在的迁移。

这是一个易于使用的清除迁移的快捷方式，我从this blog post中找到了。只需从CLI的根项目文件夹中运行以下命令：

find . -path "*/migrations/*.py" -not -name "__init__.py" -not -path "./env/*" -delete
find . -path "*/migrations/*.pyc" -not -path "./env/*" -delete

然后，删除您的sqlite数据库，然后再次尝试迁移。

如果在错误的目录中运行此命令，则将破坏Django下载以及所有使用迁移的第三方Django应用！

我经常使用它，所以我将其设为bash function：

function djclear() {
  dir="${PWD##*/}"
  if [ -d $dir ]; then
       find . -path "*/migrations/*.py" -not -name "__init__.py" -not -path "./env/*" -delete
       find . -path "*/migrations/*.pyc" -not -path "./env/*" -delete
  else
    echo "Returning with exit code 1. Are you sure that you are in a project directory?"
    return 1
  fi
}

这看起来很复杂，但是实际上它只是在执行命令之前确认您在Django Project文件夹中。

Answer 3

尝试从 Documentation执行以下操作：

从PyPI安装：

pip install django-background-tasks

添加到settings.py中的INSTALLED_APPS。

INSTALLED_APPS = (
# ...
'background_task',
# ...
)

检查您的迁移是否一切正常。

python manage.py showmigrations

迁移数据库，并检查background_task文件是否已添加到迁移列表中。

python manage.py migrate

使用您想要使用background_tasks的任何方式对视图进行修改。例如，您可以查找一个用户ID并向他们发送消息。

from background_task import background
from django.contrib.auth.models import User

@background(schedule=60)
def notify_user(user_id):
    # lookup user by id and send them a message
    user = User.objects.get(pk=user_id)
    user.email_user('Here is a notification', 'You have been notified')

新鲜的mysql数据库获取“ mydb.background_task不存在”-Django

3 个答案: