Well... Problem closed. I was trying to override things that I shouldn't. Now I got the idea of returning manager by __get__ and everything is just fine :)
On Jun 27, 11:13 pm, Vladimir Shulyak <nc0...@gmail.com> wrote: > Hello, > > I am trying to develop sublcass of models.ManyToManyField. This class > should return text representations of objects to forms.TextField (like > TagField from django-tagging). The reason to make my own > representation is because: > - I don't need content types > - I need "front face" to ManyToManyField, but TagField uses CharField > and stores duplicate data. > > So I come to implementing my own descriptor and field like this > (minimal code just to show exception, dpaste of same code for syntax > highlightinghttp://dpaste.com/60470/): > > #descriptor of field > class MultiModelSubclassDescriptor > (ReverseManyRelatedObjectsDescriptor): > > def __init__(self, m2m_field): > super(MultiModelSubclassDescriptor, self).__init__(m2m_field) > > def __get__(self, instance, instance_type=None): > from products.models import Ingridient > return ", ".join(["%s" % ing.name for ing in > Ingridient.objects.all()]) > #super(MultiModelSubclassDescriptor, self).__get__(instance, > instance_type) > > def __set__(self, instance, value): > pass > #super(MultiModelSubclassDescriptor, self).__set__(instance, > value) > > #field > class MultiModelSubclassField(ManyToManyField): > > def __init__(self, to, **kwargs): > super(MultiModelSubclassField, self).__init__(to, **kwargs) > > def contribute_to_class(self, cls, name): > super(MultiModelSubclassField, self).contribute_to_class(cls, > name) > > # Make this object the descriptor for field access. > setattr(cls, self.name, MultiModelSubclassDescriptor(self)) > > def value_from_object(self, obj): > "Returns the value of this field in the given model instance." > return getattr(obj, self.attname) #original getattr(obj, > self.attname).all() for queryset > > def formfield(self, **kwargs): > f = FormCharField(widget = TextInput()) > return f > > But as my field is a subclass of ManyToManyField, django tries to get > PKs of my object, not value. > Piece of django code which is responsible for it: > > for f in opts.fields + opts.many_to_many: > if not f.editable: > continue > if fields and not f.name in fields: > continue > if exclude and f.name in exclude: > continue > if isinstance(f, ManyToManyField): > # If the object doesn't have a primry key yet, just use an > empty > # list for its m2m fields. Calling f.value_from_object > will raise > # an exception. > if instance.pk is None: > data[f.name] = [] > else: > # MultipleChoiceWidget needs a list of pks, not object > instances. > data[f.name] = [obj.pk for obj in f.value_from_object > (instance)] """ HERE I get exception """ > > else: > data[f.name] = f.value_from_object(instance) > > There is a hack I to overcome this I beleive... > > Any help much appreciated, I am fighting with it for 4 days... > Thanks. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/django-users?hl=en -~----------~----~----~----~------~----~------~--~---
