how to limit_choices_to self field id in django model - django

Question

how use limit_choices_to in django
class Category(models.Model):
"""
商品类别
"""
CATEGORY_TYPE = (
(1, "一级类目"),
(2, "二级类目"),
(3, "三级类目"),
)
def limit_category_type_choice(self):
obj = Category.objects.get(category_type=self.category_type)
field_object = Category._meta.get_field('category_type')
field_value = field_object.value_from_object(obj)
return {'category_type__lte': field_value}
category_id = models.AutoField(primary_key=True, verbose_name='category_id')
category_title = models.CharField(default='', max_length=50, verbose_name='目录标题', help_text='目录标题')
category_name = models.ForeignKey(LinkDesignate,blank=True, null=True, to_field='link_des_text_id', related_name='category', on_delete=models.CASCADE)
category_type = models.IntegerField(choices=CATEGORY_TYPE, verbose_name="类目级别", help_text="类目级别")
parent_category = models.ForeignKey("self", limit_choices_to=self.limit_category_type_choice, null=True, blank=True, verbose_name="父类目级别", help_text="父目录",
related_name="sub_cat", on_delete=models.CASCADE)
class Meta:
verbose_name = "产品目录"
verbose_name_plural = verbose_name
i know this
limit_choices_to=self.limit_category_type_choice,
this is wrong , because name 'self' is not defined
how can to use the function limit_category_type_choice
the document is:
def limit_pub_date_choices():
return {'pub_date__lte': datetime.date.utcnow()}
limit_choices_to = limit_pub_date_choices
how can i change my Function limit_category_type_choice without self
but can use the self instance

Answer 1

Put the def out of the class ;-)
This was my solution, it is similar.
It limits the films which can be choosen for an event.
Films with status '2' in class Film over ForeignKey OR
over reverse ForeignKey: Films with an Event with date in the future
the model:
def limit_film_choices():
date = str(datetime.datetime.now())
result = Q( status = '2') | Q( event_film__date__gte = date)
return result
class Film(models.Model):
STATUS_COICES = [
('1' , 'a'),
('2' , 'b'),
]
status = models.CharField( max_length=16, choices=STATUS_COICES, default='1')
class Event(models.Model):
film = models.ForeignKey('filme.Film', on_delete=models.CASCADE, related_query_name='event_film',
related_name='event_film', blank = True, null=True, limit_choices_to = limit_film_choices)
date = models.DateTimeField(auto_now=False, null=True)