How to list all object in m2m field in parent model from child model?

Using Django Using the ORM
1

I am trying to call the list of M2M objects referenced in ModelB from ModelC.

I normally use it the other way around (start with parent model and filter down to child), but this time I cant see a way around it.

I feel there might be something to do with the related name, but the behaviour seems different than with normal FK.

I tried different options. The most commonly suggested is to use _set.all which I cant seem to make work.

class ModelA(models.Model):
    title = models.CharField(verbose_name="title",max_length=100, null=True, blank=True)

class ModelB(models.Model):
    ModelB_Field1= models.ManyToManyField(ModelA, blank=True)
    
class ModelC(models.Model):
    ModelC_Field1= models.ForeignKey(ModelB,null=True, blank=True, on_delete=models.SET_NULL, related_name='modelc_field1')

def function(request, modelc_id):
    q = ModelC.objects.get(pk=modelc_id).modelC_field1_set.all()

Doing this gives the following error: :'ModelC' object has no attribute 'ModelC_Field1_set'

How can I access all the objects in m2m field in ModelB model from ModelC?

2

You’re not showing an M2M between ModelB and ModelC. You’re showing a O2M from ModelB to ModelC.

The function you’re showing is querying on ModelC - that’s a forward reference directly through ModelC_Field1 to get the related ModelB.

You use the related name when making the reverse reference from ModelB. If you have an instance of ModelB named model_b, then the set of ModelC related to model_b is model_b.modelc_field1.