Can not use EAV model in ManyToMany relation

[haizaar]

Consider the following example:

class Fruit(BaseEntity):
    title = models.CharField(max_length=50)

class Customer(models.Model):
   name = models.CharField(max_length=50)
   fruits = odels.ManyToManyField(Fruit)

Trying to edit Customer in django admin will complain:

Caught AttributeError while rendering: Fruit does not have attribute named "attrs".

The problem is that django ModelMultipleChoiceField does this:

    def prepare_value(self, value):
        if hasattr(value, '__iter__'):
            return [super(ModelMultipleChoiceField, self).prepare_value(v) for v in value]
        return super(ModelMultipleChoiceField, self).prepare_value(value)

I.e. since Fruit has __iter__ method, prepare_value tries to iterate it and it goes wrong.