我有一個名爲Card的模型,它與 Tag有ManyToMany關係。當我保存一張卡片時,我想創建一個產品,我希望它具有與標籤相同的ManyToMany關係。保存方法manytomany
如何訪問實例的標籤? self.tags.all()
給出了一個空的 列表,如果我在保存後檢查,卡實際上有標籤。我的 代碼如下。爲了記錄,我使用的是Django 1.0.5。
class Card(models.Model):
product = models.ForeignKey(Product, editable=False, null=True)
name = models.CharField('name', max_length=50, unique=True, help_text='A short and unique name or title of the object.')
identifier = models.SlugField('identifier', unique=True, help_text='A unique identifier constructed from the name of the object. Only change this if you know what it does.', db_index=True)
tags = models.ManyToManyField(Tag, verbose_name='tags', db_index=True)
price = models.DecimalField('price', max_digits=15, decimal_places=2, db_index=True)
def add_product(self):
product = Product(
name = self.name,
identifier = self.identifier,
price = self.price
)
product.save()
return product
def save(self, *args, **kwargs):
# Step 1: Create product
if not self.id:
self.product = self.add_product()
# Step 2: Create Card
super(Card, self).save(*args, **kwargs)
# Step 3: Copy cards many to many to product
# How do I do this?
print self.tags.all() # gives an empty list??