Django query based on another query results

Question

I have 4 models in my simplified design

class modelA(models.Model):
     name = models.CharField()

class modelsUser(model.Model):
     username = models.CharField()

class bridge(models.Model):
     user = models.ForeignKey(modelUser, on_delete=models.CASCADE, related_name='bridges')
     modelA = models.ForeignKey(modelA, on_delete=models.CASCADE, related_name='bridges')

class subModelA(models.Model):
     modelA = models.ForeignKey(modelA, on_delete=models.CASCADE, related_name='subModelAs')
     value = models.IntegerField()

class subModelB(models.Model):
     modelA = models.ForeignKey(modelA, on_delete=models.CASCADE, related_name='subModelBs')
     text = models.TextField()

What I am trying to to is to get all subModelBs and subModelAs that are for modelAs for which given modelUser have bridge.

I've started with this:

user = modelUser.objects.get(pk=1)
bridges = user.bridges.all()

What I've been thinking is something like this:

subModelBs = subModelB.objects.filter(modelA__in=bridges__modelA)

but unfortunately it doesn't work because of error that __modelA is not defined.

Is there any proper way to do this?

subModelBs = subModelB.objects.filter(modelA__in=user.bridges.all().values_list("modelA", flat=True))? — Swetank Poddar
– Swetank Poddar, Commented Apr 25, 2020 at 18:58

Horatiu Airbase · Accepted Answer · 2020-04-25 19:00:05Z

3

Find first the modelAs and then do two other queries:

modelAs = bridge.objects.filter(user__pk=1).values_list('modelA', flat=True)

subModelAs = subModelA.object.filter(modelA__in=modelAs)
subModelBs = subModelB.object.filter(modelA__in=modelAs)

edited Apr 25, 2020 at 19:00

answered Apr 25, 2020 at 18:51

Horatiu Airbase

563 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Ayush Pallav · Accepted Answer · 2020-04-25 18:44:14Z

1

A good question first of all!

Tried reproducing on my system, the following worked for me:

user = modelUser.objects.get(pk=1)
bridges = user.bridges.all()
subModelAs = subModelA.objects.filter(
    modelA_id__in=[x.modelA_id for x in list(bridges)]
)

And similarly for subModelBs. Hope this helps you well.

answered Apr 25, 2020 at 18:44

Ayush Pallav

1,0571 gold badge10 silver badges21 bronze badges

Collectives™ on Stack Overflow

Django query based on another query results

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related