Question

我定义了两个模型

from django.db import models

class Blog(models.Model):
    title = models.CharField(max_length=144)

    @property
    def posts(self):
        self.Post_set.all()

class Post(models.Model):
    title = models.CharField(max_length=144)
    text = models.TextField()
    blog = models.ForeignKey('Blog')

但问题是，当我运行shell时，输入

>>> blog = Blog(title="My blog")
>>> post = Post(title="My first post", text="Here is the main text for my blog post", blog=blog)
>>> blog.posts

我收到错误

Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "/home/lucas/Programming/Python/Django/djangorestfun/blog/models.py", line 9, in posts
    self.Post_set.all()
AttributeError: 'Blog' object has no attribute 'Post_set'
>>>

现在我遇到以下问题

>>> from blog.models import *
>>> blog = Blog(title="gewrhter")
>>> blog.save()
>>> blog.__dict__
{'_state': <django.db.models.base.ModelState object at 0x259be10>, 'id': 1, 'title': 'gewrhter'}
>>> blog._state.__dict__
{'adding': False, 'db': 'default'}
>>> post = Post(title="sdhxcvb", text="hdbfdgb", blog=blog)
>>> post.save()
>>> post.__dict__
{'blog_id': 1, 'title': 'sdhxcvb', 'text': 'hdbfdgb', '_blog_cache': <Blog: Blog object>, '_state': <django.db.models.base.ModelState object at 0x259bed0>, 'id': 1}
>>> blog.posts
>>> print blog.posts
None

第二次更新

所以我跟着你的导游，但我仍然一无所获。另外，blog.posts给我一个错误。

>>> from blog.models import *
>>> blog = Blog(title="asdf")
>>> blog.save()
>>> post = Post(title="asdf", text="sdxcvb", blog=blog)
>>> post.save()
>>> blog.posts
Traceback (most recent call last):
  File "<console>", line 1, in <module>
AttributeError: 'Blog' object has no attribute 'posts'
>>> print blog.all_posts
None

Answer 1

post_set应为小写：

self.post_set.all()

<强>更新

事实证明，您确实可以在名为Blog的{{1}}上创建一个属性，并让它返回一个博客帖子的列表：

posts

class Blog(models.Model): title = models.CharField(max_length=144) @property def posts(self): return self.post_set.all() # note the `return`现在实际上是blog.posts的别名。因此，以下查找现在将起作用：

blog.post_set.all()

最后，要获取每个对象的字典值列表，您可以按以下方式操作from main.models import * blog = Blog(title="asdf") blog.save() post = Post(title="asdf", text="sdxcvb", blog=blog) post.save() blog.posts # returns [<Post: Post object>] blog.post_set.all() # returns [<Post: Post object>]：

blog.posts

Answer 2

或更好，请使用related_name：

class Post(models.Model):
    title = models.CharField(max_length=144)
    text = models.TextField()
    blog = models.ForeignKey('Blog', related_name="posts")

你可以这样做：

from main.models import *

post = Post(title="asdf", text="sdxcvb", blog=blog)
post.posts.create("asdf") #Create it "inline"

blog = Blog(title="another_asdf")
post.posts.add(blog) #Added it (don't need call save method!)

blog.posts.all() # returns [<Post: Post object>]

然后使用value方法

blog.posts.values() 
# [{'id': 1, 'tile': 'asdf', 'text': 'sdxcvb', 'blog': 'THE_BLOG_ID'}]

希望有所帮助！

当我为子模型调用_set.all（）时，为什么django会给我一个属性错误？

第二次更新

2 个答案: