Django executing backward relation query occurred a maximum recursion depth exceeded error when I use Manager

Question

Here's the code:

class CarSource

class CarSource(models.Model):
    status = models.CharField(max_length=1, blank=True, null=True)
    dealer = models.ForeignKey(Dealer, blank=True, null=True, \
                  on_delete=models.SET_NULL, related_name='cars', \
                  verbose_name=u'dealer own this car')
    objects = CarSourceManager()

class Dealer

class Dealer(models.Model):
    ...

class CarSourceManager:

class CarSourceManager(models.Manager):
    ''' Manage query in CarSource, filter data that was processed successfully.'''
    def get_query_set(self):
        return super(self.__class__, self).get_query_set().filter(status='S')

When I execute this:

from ... import Dealer
d = Dealer.objects.get(id = 2)
d.cars.all()

It occur error as below:

File "/...path..of..error..file../apps/car/managers.py", line 9, in all
return super(self.__class__, self).all().filter(status='S')
File "/...path..of..error..file../apps/car/managers.py", line 9, in all
return super(self.__class__, self).all().filter(status='S')
File "/...path..of..error..file../apps/car/managers.py", line 9, in all
return super(self.__class__, self).all().filter(status='S')
File "/...path..of..error..file../apps/car/managers.py", line 9, in all
return super(self.__class__, self).all().filter(status='S')
File "/...path..of..error..file../apps/car/managers.py", line 9, in all
return super(self.__class__, self).all().filter(status='S')
File "/...path..of..error..file../apps/car/managers.py", line 9, in all
return super(self.__class__, self).all().filter(status='S')
File "/...path..of..error..file../apps/car/managers.py", line 9, in all
return super(self.__class__, self).all().filter(status='S')
RuntimeError: maximum recursion depth exceeded while calling a Python object

I overwrite the get_query_set of models.Manager in CarSourceManager, obviously, it continue call it self recursively. I've watched the code of Manager but can't figure it out, please help me.

By the way, My django version is 1.4.2 – weidwonder Aug 14 '15 at 08:06 — weidwonder, Aug 14 '15 at 08:06

score 2 · Accepted Answer · edited May 23 '17 at 11:47

2

See this answer: https://stackoverflow.com/a/18208725/1085511

Basically you can not use

super(self.__class__, self)

Use

super(CarSourceManager, self)

instead.

The related manager's self.__class__ is different from CarSourceManager therefore the loop.

edited May 23 '17 at 11:47

Community

1
1

answered Aug 14 '15 at 08:35

Krzysztof Szularz

5,151
24
35

haaa, it works!! thx very much, but I'm new to stackoverflow, have no reputation, can't upvote ur answer. Sorry about that. seems that I still need to learn python hard.;) thank u again! – weidwonder Aug 14 '15 at 09:20

score 0 · Answer 2 · answered Aug 14 '15 at 08:35

0

This is exactly why you have to name the class explicitly when you call super:

return super(CarSourceManager, self).get_query_set().filter(status='S')

answered Aug 14 '15 at 08:35

Daniel Roseman

588,541
66
880
895

Yeah! thank u, u are right. I'm new to stackoverflow, have no reputation, can't upvote ur answer. Sorry about that. I will upvote later. – weidwonder Aug 14 '15 at 09:22

Django executing backward relation query occurred a maximum recursion depth exceeded error when I use Manager

2 Answers2