[英]Convert django RawQuerySet to Queryset
I have 2 Django models, ModelA
with an ArrayField
that is used to store a large list of primary key values (possibly 50k+ list)我有 2 个 Django 模型,
ModelA
带有一个ArrayField
,用于存储主键值的大列表(可能是 50k+ 列表)
class ModelA(models.Model):
pk_values = ArrayField(models.IntegerField())
class CustomManager(manager.Manager):
def get_for_index(self, index_id):
qs = self.get_queryset()
obj = ModelA.objects.get(pk=index_id)
return qs.filter(id__in=obj.pk_values)
class ModelB(models.Model):
# [...] some fields
objects = CustomManager()
This works:这有效:
qs = ModelB.objects.get_for_index(index_id=1)
However, this would be super slow where "pk_values" is a large list.但是,在“pk_values”是一个大列表的情况下,这将非常慢。
So I tried doing raw SQL queries:所以我尝试做原始 SQL 查询:
class CustomManager(manager.Manager):
def get_for_index(self, index_id):
qs = self.get_queryset()
sql = "SELECT * FROM myapp_model_b JOIN myapp_model_a ON myapp_model_b.id = ANY(myapp_model_a.pk_values) WHERE myapp_model_a.id = '%s'" % index_id
return qs.raw(sql)
But this returns a django.db.models.query.RawQuerySet
instance.但这会返回一个
django.db.models.query.RawQuerySet
实例。
But with this, I cant do things like queryset.values()
afterwards.但是有了这个,我之后就不能做
queryset.values()
类的事情了。
How can I convert this to a normal Django queryset?如何将其转换为普通的 Django 查询集?
Is there a better way of doing this?有没有更好的方法来做到这一点?
Docs:文档:
You can use a RawSQL expression:您可以使用RawSQL表达式:
ModelB.objects.filter(id__in=RawSQL(
'SELECT unnest(a.pk_values) FROM app_modela a WHERE a.id = %s',
[index_id]
))
Alternatively you can reproduce the exact query you have in your question with extra() :或者,您可以使用extra()重现您在问题中的确切查询:
ModelB.objects.extra(
tables=['foo_modela'],
where=[
'"app_modelb"."id" = ANY("app_modela"."pk_values")',
'"app_modela"."id" = %s',
],
params=[index_id],
)
Update: I got something working using .extra()
更新:我使用
.extra()
得到了一些工作
class CustomManager(manager.Manager):
def get_for_index(self, index_id):
qs = self.get_queryset()
sql = "myapp_model_b.id IN (SELECT UNNEST(myapp_model_a.pk_values) FROM myapp_model_a WHERE myapp_model_a.id='%s')" % index_id
return qs.extra(where=[sql])
Docs: https://docs.djangoproject.com/en/2.0/ref/models/querysets/#django.db.models.query.QuerySet.extra文档: https : //docs.djangoproject.com/en/2.0/ref/models/querysets/#django.db.models.query.QuerySet.extra
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