Django - 保存新对象时如何获取self.id? [英] Django - How to get self.id when saving a new object?
问题描述
self.id
。 models.py
类自行车AdItemKind(MPTTModel):
def url(self,filename):
pdb.set_trace()
url =MultimediaData / HelpAdImages / ItemKind /%s /%s %(self.id,filename)
return url
def item_kind_image(self):
return'< img align =middlesrc =/ media /%s height =60px/>'%self.image
item_kind_image.allow_tags = True
#Bicicleta completa,Componentes para bicicleta,Acessorios para ciclista
n_item_kind = models。 CharField(max_length = 50)
parent = TreeForeignKey('self',null = True,
blank = True,related_name ='children')
description = models.TextField(null = BLAN k = True)
image = models.ImageField(upload_to = url,null = True,blank = True)
date_inserted = models.DateTimeField(auto_now_add = True)
date_last_update = models.DateTimeField auto_now = True)
def __unicode __(self):
return self.n_item_kind
class MPTTMeta:
order_insertion_by = ['n_item_kind']
问题出在 url()
在更新对象时,我只能得到 self.id
,当创建一个对象时,我不会得到 self.id
新的对象。如何修改此模型,以便在创建新对象时获取 self.id
?
使用当前代码,当我创建一个新对象时,我将最终得到一个如下所示的URL:
MultimediaData / HelpAdImages / ItemKind / None /somefile.jpg
我需要有一些类似的东西:
MultimediaData / HelpAdImages / ItemKind / 35 / somefile.jpg
任何线索?
如果是新对象,则需要先保存,然后访问自身。 id,因为
在调用save()之前,没有办法知道ID的价值是什么,
,因为该值是由数据库计算而不是由Django计算的。
检查django的文档https://docs.djangoproject.com/en/dev/ref/models/instances/
I have a problem in one of my models. I'm uploading an image, and I want to store the id (pk in the database table) but I need to know at which point Django will have access to self.id
.
models.py
class BicycleAdItemKind(MPTTModel):
def url(self, filename):
pdb.set_trace()
url = "MultimediaData/HelpAdImages/ItemKind/%s/%s" % (self.id, filename)
return url
def item_kind_image(self):
return '<img align="middle" src="/media/%s" height="60px" />' % self.image
item_kind_image.allow_tags = True
# Bicicleta completa, Componentes para bicicleta, Acessorios para ciclista
n_item_kind = models.CharField(max_length=50)
parent = TreeForeignKey('self', null=True,
blank=True, related_name='children')
description = models.TextField(null=True, blank=True)
image = models.ImageField(upload_to=url, null=True, blank=True)
date_inserted = models.DateTimeField(auto_now_add=True)
date_last_update = models.DateTimeField(auto_now=True)
def __unicode__(self):
return self.n_item_kind
class MPTTMeta:
order_insertion_by = ['n_item_kind']
The problem is in the url()
method; I can only get self.id
when updating an object, I don't get the self.id
when creating a new object. How can I modify this model so that I get self.id
when creating a new object?
With the current code, when I'm creating a new object I will end up with a url like:
MultimediaData/HelpAdImages/ItemKind/None/somefile.jpg
And I need to have something like:
MultimediaData/HelpAdImages/ItemKind/35/somefile.jpg
Any clues?
If it's a new object, you need to save it first and then access self.id, because
"There's no way to tell what the value of an ID will be before you call save(),
because that value is calculated by your database, not by Django."
Check django's document https://docs.djangoproject.com/en/dev/ref/models/instances/
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