我正在尝试获取一个查询集，其中一个任务有两个已在10秒内创建的发行。
模型如下：
Class Task(models.Model):
# stuff
Class Issuance(models.Model):
task = models.ForeignKey(Task, blank=True, null=True, on_delete=models.SET_NULL)
created = models.DateTimeField(default=timezone.now)
到目前为止我得到了什么：
qs = (
Task.objects
.annotate(count=Count('issuance'))
.filter(count__gt=1, count__lte=2)
.annotate(time_difference=F('issuance__created')) # Need to fix this
.annotate(
dupe=Case(
When(
time_difference__lt=10, # Less than 10 seconds
then=Value(1),
),
default=Value(0),
output=BooleanField(),
)
)
)
我认为我非常接近但我需要一些方法来计算任何一个任务的两个发行的创建日期之间的时间差。另外，需要进行时间差小于10秒的比较;不确定我的工作是否有效。
有人可以帮忙吗？
编辑：添加了查询输出
TypeError Traceback (most recent call last)
<ipython-input-47-e0e60776551e> in <module>()
11 ),
12 default=Value(0),
---> 13 output=BooleanField(),
14 )
15 )
/usr/local/lib/python3.6/site-packages/django/db/models/query.py in annotate(self, *args, **kwargs)
912 raise ValueError("The annotation '%s' conflicts with a field on "
913 "the model." % alias)
--> 914 clone.query.add_annotation(annotation, alias, is_summary=False)
915
916 for alias, annotation in clone.query.annotations.items():
/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py in add_annotation(self, annotation, alias, is_summary)
969 """
970 annotation = annotation.resolve_expression(self, allow_joins=True, reuse=None,
--> 971 summarize=is_summary)
972 self.append_annotation_mask([alias])
973 self.annotations[alias] = annotation
/usr/local/lib/python3.6/site-packages/django/db/models/expressions.py in resolve_expression(self, query, allow_joins, reuse, summarize, for_save)
827 c.is_summary = summarize
828 for pos, case in enumerate(c.cases):
--> 829 c.cases[pos] = case.resolve_expression(query, allow_joins, reuse, summarize, for_save)
830 c.default = c.default.resolve_expression(query, allow_joins, reuse, summarize, for_save)
831 return c
/usr/local/lib/python3.6/site-packages/django/db/models/expressions.py in resolve_expression(self, query, allow_joins, reuse, summarize, for_save)
760 c.is_summary = summarize
761 if hasattr(c.condition, 'resolve_expression'):
--> 762 c.condition = c.condition.resolve_expression(query, allow_joins, reuse, summarize, False)
763 c.result = c.result.resolve_expression(query, allow_joins, reuse, summarize, for_save)
764 return c
/usr/local/lib/python3.6/site-packages/django/db/models/query_utils.py in resolve_expression(self, query, allow_joins, reuse, summarize, for_save)
79 # We must promote any new joins to left outer joins so that when Q is
80 # used as an expression, rows aren't filtered due to joins.
---> 81 clause, joins = query._add_q(self, reuse, allow_joins=allow_joins, split_subq=False)
82 query.promote_joins(joins)
83 return clause
/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py in _add_q(self, q_object, used_aliases, branch_negated, current_negated, allow_joins, split_subq)
1251 child, can_reuse=used_aliases, branch_negated=branch_negated,
1252 current_negated=current_negated, connector=connector,
-> 1253 allow_joins=allow_joins, split_subq=split_subq,
1254 )
1255 joinpromoter.add_votes(needed_inner)
/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py in build_filter(self, filter_expr, branch_negated, current_negated, can_reuse, connector, allow_joins, split_subq)
1141 clause = self.where_class()
1142 if reffed_expression:
-> 1143 condition = self.build_lookup(lookups, reffed_expression, value)
1144 clause.add(condition, AND)
1145 return clause, []
/usr/local/lib/python3.6/site-packages/django/db/models/sql/query.py in build_lookup(self, lookups, lhs, rhs)
1081 lhs = self.try_transform(lhs, name, lookups)
1082 final_lookup = lhs.get_lookup('exact')
-> 1083 return final_lookup(lhs, rhs)
1084 lhs = self.try_transform(lhs, name, lookups)
1085 lookups = lookups[1:]
/usr/local/lib/python3.6/site-packages/django/db/models/lookups.py in __init__(self, lhs, rhs)
17 def __init__(self, lhs, rhs):
18 self.lhs, self.rhs = lhs, rhs
---> 19 self.rhs = self.get_prep_lookup()
20 if hasattr(self.lhs, 'get_bilateral_transforms'):
21 bilateral_transforms = self.lhs.get_bilateral_transforms()
/usr/local/lib/python3.6/site-packages/django/db/models/lookups.py in get_prep_lookup(self)
57 return self.rhs._prepare(self.lhs.output_field)
58 if self.prepare_rhs and hasattr(self.lhs.output_field, 'get_prep_value'):
---> 59 return self.lhs.output_field.get_prep_value(self.rhs)
60 return self.rhs
61
/usr/local/lib/python3.6/site-packages/django/db/models/fields/__init__.py in get_prep_value(self, value)
1415
1416 def get_prep_value(self, value):
-> 1417 value = super(DateTimeField, self).get_prep_value(value)
1418 value = self.to_python(value)
1419 if value is not None and settings.USE_TZ and timezone.is_naive(value):
/usr/local/lib/python3.6/site-packages/django/db/models/fields/__init__.py in get_prep_value(self, value)
1273 def get_prep_value(self, value):
1274 value = super(DateField, self).get_prep_value(value)
-> 1275 return self.to_python(value)
1276
1277 def get_db_prep_value(self, value, connection, prepared=False):
/usr/local/lib/python3.6/site-packages/django/db/models/fields/__init__.py in to_python(self, value)
1376
1377 try:
-> 1378 parsed = parse_datetime(value)
1379 if parsed is not None:
1380 return parsed
/usr/local/lib/python3.6/site-packages/django/utils/dateparse.py in parse_datetime(value)
91 Returns None if the input isn't well formatted.
92 """
---> 93 match = datetime_re.match(value)
94 if match:
95 kw = match.groupdict()
TypeError: expected string or bytes-like object