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 highlighting http://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 -~----------~----~----~----~------~----~------~--~---
