如何解决使用queryset.values_list
关于查询集中带注释的用法以及函数values_list的用法,我正面临着一个非常痛苦的问题。在我的一个核心应用程序中,我有一个manager.py,用于执行一些详细操作:
class ProcedureManager(InheritanceManager):
def get_queryset(self):
core_models = importlib.import_module('core.models')
queryset = super(ProcedureManager,self).get_queryset().select_subclasses()
return queryset.annotate(
total=Coalesce(
Count('images__marks'),0
),total_images_count=Coalesce(
Count('images'),processed_images_count=Coalesce(
Count('images',filter=models.Q(images__status=True)),status=models.Case(
models.When(processed_images_count__gt=0,then=True),default=False,output_field=models.BooleanField()
),positive=Exists(
core_models.ImageMark.objects.filter(
pattern__positive=True,image__procedure__pk=OuterRef('pk')
)
),suggested=Exists(
core_models.ImageMark.objects.filter(
suggested_pattern__positive=True,image__procedure__pk=OuterRef('pk')
)
)
)
此类用于我在models.py中的一个模型中
class Procedure(models.Model):
objects = ProcedureManager()
city = models.ForeignKey('accounts.City',on_delete=models.CASCADE)
type = models.ForeignKey('core.ProcedureType',on_delete=models.CASCADE)
company = models.ForeignKey(
'accounts.Company',related_name='procedures',on_delete=models.CASCADE)
......
def mark_result(self):
if self.pk is None:
return {}
lookup = 'images__marks__pattern__name'
queryset = Procedure.objects.filter(pk=1954)
data = queryset.values_list(lookup,models.Count(lookup))
return {pattern: count for pattern,count in data if pattern is not None}
def get_suggested_patterns(self):
if self.pk is None:
return {}
lookup = 'images__marks__suggested_pattern__name'
queryset = Procedure.objects.filter(pk=self.pk)
data = queryset.values_list(lookup,models.Count(lookup))
return {suggested: count for suggested,count in data if suggested is not None}
我在模板html中使用了一些模板标记,如下所示:
@register.simple_tag
def build_positive_tooltip(procedure):
result = procedure.mark_result()
patterns = list(result.keys())
suggested_results = procedure.get_suggested_patterns()
suggested_patterns = list(suggested_results.keys())
if procedure.positive:
if len(patterns) == 0:
return 'Os padrões sugeridos precisam ser confirmados.'
return 'Foram encontrados os seguintes padrões: {}.'.format(','.join(patterns))
现在,每次我运行应用程序并尝试在界面上获取此信息时,我都会不断收到以下错误消息:
File "/opt/environments/api/lib/python3.8/site-packages/django/db/backends/utils.py",line 86,in _execute
return self.cursor.execute(sql,params)
File "/opt/environments/api/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/environments/api/lib/python3.8/site-packages/django/db/backends/utils.py",params)
django.db.utils.ProgrammingError: column "suggested" does not exist
LINE 1: ... 1954 GROUP BY "core_procedure"."id","positive","suggested...
File "<console>",line 1
ile "/opt/environments/api/lib/python3.8/site-packages/django/db/backends/utils.py",line 68,in execute
所有这些都是在我需要添加ProcedureManager中建议的注释之后开始的:
suggested=Exists(
core_models.ImageMark.objects.filter(
suggested_pattern__positive=True,image__procedure__pk=OuterRef('pk')
)
)
通过查看Django日志,我知道该错误是在以下行中触发的:
lookup = 'images__marks__pattern__name'
queryset = Procedure.objects.filter(pk=1954)
data = queryset.values_list(lookup,models.Count(lookup))
当尝试在python manage.py shell中执行这些行时,出现相同的错误。奇怪的是,如果我在django shell上运行
from core.models import Procedure
p = list(Procedure.objects.filter(pk=2223))[0]
p.suggested
它会在控制台上正确打印注释,而不会出现任何错误。
有人知道这个问题的可能原因吗????
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