我正在尝试编写一个简单的模型管理器,它将对特定字段进行过滤
我有一个模型,看起来像这样:
"""Model definition for Period."""
year = models.ForeignKey(Year, on_delete=models.PROTECT)
name = models.CharField(max_length=50)
active = models.BooleanField(default=False)
objects = models.Manager()
active_year_periods = PeriodManager().active_year_periods()
我的周期管理器如下所示:
class PeriodManager(models.Manager):
"""
The manager for Period objects
"""
def active_year_periods(self):
"""
Gets the Period objects for the active year
Returns:
Period<Queryset> -- Periods for an active year
"""
return super().get_queryset().filter(year__active=True)
我写了一些简单的东西来测试这个特定的管理器,但是遇到了一个错误,我不确定它的意思是什么:
File "/dir/path/myapp/models.py", line 44, in <module>
class Period(models.Model):
File "/dir/path/myapp/models.py", line 55, in Period
active_year_periods = PeriodManager().active_year_periods()
File "/dir/path/myapp/managers.py", line 19, in active_year_periods
return self.get_queryset().filter(year__active=True)
File "/dir/path/venv/lib/python3.7/site-packages/django/db/models/query.py", line 892, in filter
return self._filter_or_exclude(False, *args, **kwargs)
File "/dir/path/venv/lib/python3.7/site-packages/django/db/models/query.py", line 910, in _filter_or_exclude
clone.query.add_q(Q(*args, **kwargs))
File "/dir/path/venv/lib/python3.7/site-packages/django/db/models/sql/query.py", line 1290, in add_q
clause, _ = self._add_q(q_object, self.used_aliases)
File "/dir/path/venv/lib/python3.7/site-packages/django/db/models/sql/query.py", line 1318, in _add_q
split_subq=split_subq, simple_col=simple_col,
File "/dir/path/venv/lib/python3.7/site-packages/django/db/models/sql/query.py", line 1190, in build_filter
lookups, parts, reffed_expression = self.solve_lookup_type(arg)
File "/dir/path/venv/lib/python3.7/site-packages/django/db/models/sql/query.py", line 1049, in solve_lookup_type
_, field, _, lookup_parts = self.names_to_path(lookup_splitted, self.get_meta())
File "/dir/path/venv/lib/python3.7/site-packages/django/db/models/sql/query.py", line 297, in get_meta
return self.model._meta
AttributeError: 'NoneType' object has no attribute '_meta'
这个错误在我的测试运行之前就已经开始了——我的测试目前被构建为失败,但它甚至不会因为这个错误而失败
这是我的测试:
class TestPeriodManager(TestCase):
"""
Test cases for the Period Manager
"""
def setUp(self):
pass
def test_active_year_periods_returns_correct_amount(self):
"""
Test that the PeriodManager active_year_periods method returns
appropriate amount of Periods
"""
# periods_in_active_year = swm.Period.active_year_periods
# print(periods_in_active_year)
self.assertTrue(False)
你知道我为什么会遇到这个问题吗?我这样做完全错了吗
我正在尝试使用自定义管理器方法,以便最终可以在需要时传入参数以进行其他筛选
您需要将
active_year_periods
(您的自定义管理器)分配给管理器类,而不是方法:型号.py:
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