@lybcyd 请问用这种方法应该怎么写呢
[left-join-django-orm]( https://stackoverflow.com/questions/21271835/left-join-django-orm)
仿写了几遍,卡住了,运行不成功


```
from django.db.models.sql.datastructures import Join
from django.db.models.fields.related import ForeignObject
from django.db.models.options import Options
from myapp.models import Ace
from myapp.models import Subject

jf = ForeignObject(
to=Subject,
on_delete=lambda: x,
from_fields=[None],
to_fields=[None],
rel=None,
related_name=None
)

jf.opts = Options(Ace._meta)
jf.opts.model = Ace
jf.get_joining_columns = lambda: (("subj", "name"),)

j=Join(
Subject._meta.db_table, Ace._meta.db_table,
'T1', "LEFT JOIN", jf, True)

q=Ace.objects.filter(version=296)
q.query.join(j)

print q.query
```