Python版本：3.7 Django版本2.1.1
我是django的新手，我主要是在教程和“试错”的帮助下自学。我搜索了stackoverflow，但以前的问题似乎都不适合我的问题。例如，它们指的是空白的CharFields，我认为这不是我的问题。
我想，我通过ForeignKey将两个类的神学院和论文联系起来。现在我可以通过适当的表单将Seminary添加到数据库中，并按照我想要的方式显示它。但考虑到Paper类的第二种形式，django给了我错误：
请求方法：POST
异常类型：IntegrityError
异常值：NOT NULL约束失败：papers_paper.seminary_id
论文是我的应用程序，顺便说一句
这是models.py，没有meta：
class Seminary(models.Model):
slug = models.SlugField(unique=True)
seminary_type = models.CharField(max_length=25, choices=choices.SEMINARY_TYPE_CHOICES)
seminary_title = models.CharField(max_length=200)
seminary_year = models.IntegerField(choices=choices.YEAR_CHOICES, default=datetime.now().year)
summer_winter = models.CharField(max_length=6, choices=choices.SEASON_CHOICES, default="S")
def get_absolute_url(self):
return reverse('papers:paper-detail', kwargs={'slug': self.slug})
def __str__(self):
return self.seminary_title
def create_slug(instance, new_slug=None):
slug = slugify(instance.seminary_title)
if new_slug is not None:
slug = new_slug
qs = Seminary.objects.filter(slug=slug)
exists = qs.exists()
if exists:
new_slug = "%s-%s" % (slug, qs.first().pk)
return create_slug(instance, new_slug=new_slug)
return slug
def pre_save_post_receiver(sender, instance, *args, **kwargs):
if not instance.slug:
instance.slug = create_slug(instance)
pre_save.connect(pre_save_post_receiver, sender=Seminary)
class Paper(models.Model):
seminary = models.ForeignKey(Seminary, on_delete=models.CASCADE, primary_key=True)
paper_title = models.CharField(max_length=200, blank=False, help_text="Please enter the title ")
author = models.CharField(max_length=50, blank=True)
upload_paper = ContentTypeRestrictedFileField(
upload_to='papers/pdf',
content_types=['application/pdf'],
max_upload_size=5242880,
blank=True
)
def get_absolute_url(self):
return reverse('papers:paper-index', kwargs={'slug': self.slug})
这是views.py：
class IndexView(generic.ListView):
template_name = 'papers/index.html'
context_object_name = 'all_papers'
def get_queryset(self):
return Seminary.objects.all()
class DetailView(generic.DetailView):
model = Seminary
template_name = 'papers/detail.html'
class SeminaryCreate(CreateView):
model = Seminary
fields = ['summer_winter',
'seminary_year',
'seminary_type',
'seminary_title',
]
class PaperCreate(CreateView):
model = Paper
fields = [
'paper_title',
'author',
'upload_paper',
]
我敢肯定，我正在混淆什么。如果我需要提供更多信息，请询问，我会将其添加到我的问题中。提前致谢！
编辑：
我根据@bluegrounds的建议在PaperCreate视图中添加了神学院现在它给了我以下错误。
异常类型：NotperlyConfigured
异常值：没有要重定向到的URL。在模型上提供url或定义get_absolute_url方法。
无论如何，不应该选择研讨会：每篇论文只分配给一个特定的研讨会。
更改视图PaperCreate后完成Traceback：
Request Method: POST
Request URL: http://127.0.0.1:8000/papers/seminartitel15/add/
Django Version: 2.1.1
Python Version: 3.7.0
Installed Applications:
['django.contrib.admin',
'django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.messages',
'django.contrib.staticfiles',
'transcript.apps.TranscriptConfig',
'biblio.apps.BiblioConfig',
'papers.apps.PapersConfig',
'crispy_forms']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware']
Traceback:
File "/usr/lib/python3.7/site-packages/django/views/generic/edit.py" in get_success_url
116. url = self.object.get_absolute_url()
File "/home/bjoern/MyCode/PycharmProjects/websiteTwo/websiteTwo/papers/models.py" in get_absolute_url
68. return reverse('papers:paper-index', kwargs={'slug': self.slug})
During handling of the above exception ('Paper' object has no attribute 'slug'), another exception occurred:
File "/usr/lib/python3.7/site-packages/django/core/handlers/exception.py" in inner
34. response = get_response(request)
File "/usr/lib/python3.7/site-packages/django/core/handlers/base.py" in _get_response
126. response = self.process_exception_by_middleware(e, request)
File "/usr/lib/python3.7/site-packages/django/core/handlers/base.py" in _get_response
124. response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/usr/lib/python3.7/site-packages/django/views/generic/base.py" in view
68. return self.dispatch(request, *args, **kwargs)
File "/usr/lib/python3.7/site-packages/django/views/generic/base.py" in dispatch
88. return handler(request, *args, **kwargs)
File "/usr/lib/python3.7/site-packages/django/views/generic/edit.py" in post
172. return super().post(request, *args, **kwargs)
File "/usr/lib/python3.7/site-packages/django/views/generic/edit.py" in post
142. return self.form_valid(form)
File "/usr/lib/python3.7/site-packages/django/views/generic/edit.py" in form_valid
126. return super().form_valid(form)
File "/usr/lib/python3.7/site-packages/django/views/generic/edit.py" in form_valid
57. return HttpResponseRedirect(self.get_success_url())
File "/usr/lib/python3.7/site-packages/django/views/generic/edit.py" in get_success_url
119. "No URL to redirect to. Either provide a url or define"
Exception Type: ImproperlyConfigured at /papers/seminartitel15/add/
Exception Value: No URL to redirect to. Either provide a url or define a get_absolute_url method on the Model.
URLs.朋友:
urlpatterns = [
path('papers/new/', views.SeminaryCreate.as_view(), name='seminary-add'),
path('papers/', views.IndexView.as_view(), name='paper-index'),
path('papers/<str:slug>/', views.DetailView.as_view(), name='paper-detail'),
path('papers/<str:slug>/add/', views.PaperCreate.as_view(), name='paper-add'),
]
Edit_2：我无法解决整个问题，但@bluegrounds的建议很有帮助。另外我改变了班级论文的get_absolute_url
def get_absolute_url(self):
return reverse('papers:paper-detail', args=[str(self.seminary.slug)])
正如文档中所建议的那样。
现在我的模板出了问题，但我会为此设置一个新问题。非常感谢到目前为止！
我不是专家，但我认为这是因为您的PaperCreate视图没有办法将Paper对象链接到Seminary对象，就像数据库期望的那样。每个Paper对象都应具有Seminary对象的id，因为您已在Paper模型类中添加了该对象：
class Paper(models.Model):
seminary = models.ForeignKey(Seminary, on_delete=models.CASCADE, primary_key=True)
并且因为ForeignKey字段不能为null，所以它会提高NOT NULL constraint failed: papers_paper.seminary_id
所以也许这样做，看看它是否有效：
class PaperCreate(CreateView):
model = Paper
fields = [
'seminary',
'paper_title',
'author',
'upload_paper',
]
如果我没记错的话，CreateView应该在具有可用神学对象的网页上显示下拉菜单。
边注
你确定这里的主键属性吗？
class Paper(models.Model):
seminary = models.ForeignKey(Seminary, on_delete=models.CASCADE, primary_key=True)
IntegrityError，NOT NULL约束失败：papers_paper.seminary_id。 此错误意味着您在Paper模型中具有非空约束的外键，但在创建Paper对象时，您没有传递Seminary（外键）的值。