Question

How do I inherit a ModelManager?

class Content(models.Model):
    name = models.CharField(max_length=255, verbose_name= Name des Blogs )
    slug = models.SlugField(max_length=80, blank=True)
    objects = models.Manager()
    active = ContentActiveManager()

class ContentActiveManager(models.Manager):
    def get_query_set(self):
        return super(ContentActiveManager,self).get_query_set().filter(activated=True,show=True)

class BlogCatalog(Content):
    frequency = models.PositiveSmallIntegerField(max_length=2, choices=make_index_based_tuple(l=FREQUENCY), verbose_name= Frequenz ,)



blog = BlogCatalog.active.get(pk=1)

blog is now obviously a Content object. If I type Catalog.active.get(pk=1) I want a Content object but If I type BlogCatalog.active.get(pk=1) I want a BlogCatalog object.

How do I achieve this without being redundant?

Answer 1

Django only allows Manager inheritance from an abstract base class. To use the same manager as a non-ABC, you have to declare it explicitly.

Check out the django docs on custom managers and inheritance.

Basically, just do this:

class BlogCatalog(Content):
    frequency = models.PositiveSmallIntegerField(max_length=2, choices=make_index_based_tuple(l=FREQUENCY), verbose_name= Frequenz ,)
    active = ContentActiveManager()

Hope that helps.

Answer 2

the only way I figured out:

class Content:

    @staticmethod
    def __new__(cls, *args, **kwargs):
        super_new = super(Content, cls).__new__(cls, *args, **kwargs)
        cls.add_to_class( active , ContentActiveManager())
        return super_new

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