外键在对象上不可用

Posted 2023-02-23

【中文标题】外键在对象上不可用

【英文标题】：Foreign key not available on object

【发布时间】：2014-06-27 12:15:57

【问题描述】：

让我困惑的非常初级的问题。我在模板中显示外键 ArtWorkImages 时遇到问题，所以我想在视图中调试它，但外键 ArtworkImage 在 Artwork 上不可用：

我的模特：

from django.db import models

class Artwork(models.Model):
    title = models.CharField(max_length=200)
    body = models.TextField()
    created_at = models.DateTimeField(auto_now_add=True)

    def __unicode__(self):
        return self.title

class ArtworkImage(models.Model):
    property = models.ForeignKey(Artwork, related_name='images')
    image = models.ImageField(upload_to = "images/")

观点：

from django.shortcuts import render

from erikheide.models import Artwork
from erikheide.models import ArtworkImage

def index(request):
    artworks = Artwork.objects.all()[:5]

    artwork = artworks[0]

    images = artwork.artworkimage_set.all()

    context = 'latest_poll_list': artworks
    return render(request, 'index.html', context)

错误：

> Traceback (most recent call last):   File
> "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py",
> line 115, in get_response
>     response = callback(request, *callback_args, **callback_kwargs)   File "/home/fhp/Hentede filer/tastypie/django15/erikheide/views.py",
> line 13, in index
>     images = artwork.artworkimage_set.all() AttributeError: 'Artwork' object has no attribute 'artworkimage_set'

无效的模板（没有图像出现）

% if artworks %
    <ul>
    % for artwork in artworks %
        <li><a href=" artwork.title /"> artwork.body</a></li>

        % for image in artwork.images_set.all %
        <img src=" image.image.url ">

        % endfor %

    % endfor %
    </ul>
% else %
    <p>No artworks are available.</p>
% endif %

【参考方案1】：

您已经在ForeignKey 字段上定义了related_name，您需要使用它来遵循关系。

替换：

images = artwork.artworkimage_set.all()

与：

images = artwork.images.all()

另见：What is `related_name` used for in Django?

【讨论】：

谢谢，它工作得很好。我想我一定找到了一些旧文档，因为我使用了 _set 语法。

【参考方案2】：

试试

artwork.images.all()

改为

artwork.artworkimage_set.all()

image_set 是 RelatedManager 的默认名称。如果related_name用外键指定RelatedManager名称重新定义。