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python - 将组的所有用户添加为模型字段中的选项

问题描述

我试图将我的一个模型中的字段限制为选择属于特定组成员的所有用户。另一个字段为所有注册用户提供了一个选择。这在 shell 中工作正常：

>>> from django.contrib.auth.models import User, Group
>>> all_users = User.objects.all()
>>> all_users
<QuerySet [<User: somedude>, <User: test>, <User: testma>]>
>>> tm_users = User.objects.filter(groups__name='Testmanager')
>>> tm_users
<QuerySet [<User: somedude>, <User: testma>]>

但是如果我在模型中放入相同的代码： 

class TestPlan(models.Model):

    all_users = User.objects.all()
    all_user_choices = ((x.username, x.get_full_name()) for x in all_users)
    tm_users = User.objects.filter(groups__name='Testmanager')
    tm_user_choices = ((x.username, x.get_full_name()) for x in tm_users)
    tp_title = models.CharField(max_length=200, verbose_name='Title')
    tp_manager = models.CharField(max_length=100, blank=True,
                                 verbose_name='Test Manager',
                                  choices=tm_user_choices)
    tp_tester = models.CharField(max_length=100, blank=True,
                                 verbose_name='Tester',
                                 choices=all_user_choices)


    def __str__(self):
        return f'{self.tp_title}'

我得到以下（对我来说）没有帮助的堆栈跟踪： 

O:\somedude\Documents\Python\Django\testcases>manage.py makemigrations
Traceback (most recent call last):
  File "O:\somedude\Documents\Python\Django\testcases\manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "C:\Program Files\Python36\lib\site-packages\django\core\management\__init__.py", line 381, i
n execute_from_command_line
    utility.execute()
  File "C:\Program Files\Python36\lib\site-packages\django\core\management\__init__.py", line 357, i
n execute
    django.setup()
  File "C:\Program Files\Python36\lib\site-packages\django\__init__.py", line 24, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "C:\Program Files\Python36\lib\site-packages\django\apps\registry.py", line 112, in populate
    app_config.import_models()
  File "C:\Program Files\Python36\lib\site-packages\django\apps\config.py", line 198, in import_mode
ls
    self.models_module = import_module(models_module_name)
  File "C:\Program Files\Python36\lib\importlib\__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 994, in _gcd_import
  File "<frozen importlib._bootstrap>", line 971, in _find_and_load
  File "<frozen importlib._bootstrap>", line 955, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 665, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 678, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "O:\somedude\Documents\Python\Django\testcases\testman\models.py", line 68, in <module>
    class TestPlan(models.Model):
  File "O:\somedude\Documents\Python\Django\testcases\testman\models.py", line 70, in TestPlan
    tm_users = User.objects.filter(groups__name='Testmanager')
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\manager.py", line 82, in manage
r_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\query.py", line 844, in filter
    return self._filter_or_exclude(False, *args, **kwargs)
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\query.py", line 862, in _filter
_or_exclude
    clone.query.add_q(Q(*args, **kwargs))
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\sql\query.py", line 1263, in ad
d_q
    clause, _ = self._add_q(q_object, self.used_aliases)
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\sql\query.py", line 1287, in _a
dd_q
    split_subq=split_subq,
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\sql\query.py", line 1164, in bu
ild_filter
    lookups, parts, reffed_expression = self.solve_lookup_type(arg)
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\sql\query.py", line 1028, in so
lve_lookup_type
    _, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\sql\query.py", line 1365, in na
mes_to_path
    if field.is_relation and not field.related_model:
  File "C:\Program Files\Python36\lib\site-packages\django\utils\functional.py", line 37, in __get__

    res = instance.__dict__[self.name] = self.func(instance)
  File "C:\Program Files\Python36\lib\site-packages\django\db\models\fields\related.py", line 94, in
 related_model
    apps.check_models_ready()
  File "C:\Program Files\Python36\lib\site-packages\django\apps\registry.py", line 137, in check_mod
els_ready
    raise AppRegistryNotReady("Models aren't loaded yet.")
django.core.exceptions.AppRegistryNotReady: Models aren't loaded yet.

O:\somedude\Documents\Python\Django\testcases>

当我执行 User.objects.all() 时它可以工作，但是当我尝试按组过滤用户时它会失败。我真的不知道我在这里做错了什么。这是错误还是功能？

标签： pythondjangoorm

解决方案

“选择”字段属性不能是动态的，必须是静态集合，例如：

MONTH_CHOICES = (
    ("JANUARY", "January"),
    ("FEBRUARY", "February"),
    ("MARCH", "March"),
    # ....
    ("DECEMBER", "December"),
)

如果你需要这个限制，你可以在“django form”或者“DRF serializer”逻辑中验证这个case。

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