Question

我正在使用filter()和exclude()进行查询，具体取决于用户的搜索条件。如果指定，我也根据搜索对查询进行排序。一切正常，除非用户使用exclude()函数并尝试在related_field中排序。但它适用于filter()。

我正在使用Django 1.10和Postgresql

简化的模型如下：

class Project(models.Model):
    name = models.CharField(max_length=175)
    class Meta:
        ordering = ['name']
        db_table = 'project'

class Summary(models.Model):
    mykey = models.CharField(max_length=20, primary_key=True)
    external_order_id = models.ManyToManyField('Project', blank=True)

查询

project = InventoryProject.objects.get(name='')
# with exclude
# this one returns [], but if I do .count() it returns the correct number of rows
queryset.annotate(num_projects=Count('external_order_id')).exclude(external_order_id=project, num_projects=1).order_by('external_order_id')

# with filter
# this one works like a charm
queryset = queryset.annotate(num_projects=Count('external_order_id')).filter(external_order_id=project, num_projects=1)

我在订单之前和之后检查了.query属性，它们看起来非常不同

// before (it shows all the data)
SELECT "summary"."mykey", 
    COUNT("summary_external_order_id"."project_id") AS "num_projects" 
    FROM "summary" 
    LEFT OUTER JOIN "summary_external_order_id" ON ("summary"."mykey" = "summary_external_order_id"."summary_id") 
    GROUP BY "summary"."mykey" 
    HAVING NOT ("summary"."mykey" IN 
        (SELECT U1."summary_id" AS Col1 FROM "summary_external_order_id" U1 WHERE U1."project_id" = 1) AND COUNT("summary_external_order_id"."project_id") = 1)

// after (doesn't show any data)
SELECT "summary"."mykey", 
    COUNT("summary_external_order_id"."project_id") AS "num_projects" 
    FROM "summary" 
    LEFT OUTER JOIN "summary_external_order_id" ON ("summary"."mykey" = "summary_external_order_id"."summary_id") 
    LEFT OUTER JOIN "project" ON ("summary_external_order_id"."project_id" = "project"."id") 
    GROUP BY "summary"."mykey", "project"."name" 
    HAVING NOT ("summary"."mykey" IN 
        (SELECT U1."summary_id" AS Col1 FROM "summary_external_order_id" U1 WHERE U1."project_id" = 1) AND COUNT("summary_external_order_id"."project_id") = 1) 
    ORDER BY "project"."name" ASC

我不确定为什么django会自动按'mykey'分组。此外，如果我删除“项目”。“名称”来自该组的工作......

修改：这里要求的是“项目”表的数据，其中ID为1

id [pk] - integer | name - character varying(175)
1                 |

Django查询在order_by（）之后返回空数据

0 个答案: