Django snippets

from django.db.models.loading import get_model
from django.db.models.query import QuerySet
from django import template

register = template.Library()

@register.filter
def call_manager(model_or_obj, method):
    # load up the model if we were given a string
    if isinstance(model_or_obj, basestring):
        model_or_obj = get_model(*model_or_obj.split('.'))

    # figure out the manager to query
    if isinstance(model_or_obj, QuerySet):
        manager = model_or_obj
        model_or_obj = model_or_obj.model
    else:
        manager = model_or_obj._default_manager

    return getattr(manager, method)()