Question

I have the following table structures:

class Tags:
    name = fields.CharField(max_length=100)
    ref     = models.ManyToManyField(RefTags)

class RefTags
    foo = varchar(128)
    tag = models.ForeignKey('Tag')

How can I do a delete from Tags if there are no associated records in RefTags?

Thanks

Edit: I figured it out, it was really easy:

Tag.objects.filter(ref__isnull=True).delete()

Answer 1

Something like

for tag in Tags.objects.all():
    if tag not in RefTags.objects.all():
        RefTags.objects.filter(tag=tag).delete()

It probably would be more efficient to put RegTags.objects.all() in a list, cycle through it and then do the deletion.