使用queryset.values

问题描述

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？???

解决方法

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backend django django-annotate django-queryset python

使用queryset.values_list

问题描述

解决方法