Question

假设我有以下三个模型，请参见：我想构建一个Django模型查询，以存档与以下SQL语句相同的效果。

SQL语句

select B.value, C.special
from B inner join C 
where B.version = C.version and B.order = C.order;

我有以下三个模型：

class Process(models.Model):
    name = models.CharField(max_length=30)
    description = models.CharField(max_length=150)

class ProcessStep(models.Model):
    process = models.ForeignKey(Process)
    name = models.CharField(max_length=30)
    ...
    order = models.SmallIntegerField(default=1)
    version = models.SmallIntegerField(null=True)

class Approve(models.Model):
    process = models.ForeignKey(Process)
    content = models.CharField(max_length=300)
    ...
    version = models.SmallIntegerField(null=True)
    order = models.SmallIntegerField(default=0)

我想找到所有与ProcessStep模型具有相同（版本，顺序）元组匹配的Approves。

Answer 1

这样的东西？

Approve.objects.filter(process__processstep_set__order=<value>)

Answer 2

现在我只能通过使用原始SQL来提出解决方案，请参阅以下代码。

from django.db import connection
cursor = connection.cursor()
cursor.execute("
SELECT A.id, B.id 
from approval_approve as A inner join approval_approvalstep as B
where A.process_id = B.process.id 
    and A.order = B.order 
    and A.version = B.version;")
# do something with the returned data

如果你们有更好的解决方案，我想听听你的意见，谢谢〜

Django模型内部加入ORM问题

2 个答案: