python Django 表单在唯一字段上的验证失败
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Django form fails validation on a unique field
提问by Andrei Taranchenko
I have a simple model that is defined as:
我有一个简单的模型，定义为：
class Article(models.Model):
slug = models.SlugField(max_length=50, unique=True)
title = models.CharField(max_length=100, unique=False)
and the form:
和形式：
class ArticleForm(ModelForm):
class Meta:
model = Article
The validation here fails when I try to update an existing row:
当我尝试更新现有行时，此处的验证失败：
if request.method == 'POST':
form = ArticleForm(request.POST)
if form.is_valid(): # POOF
form.save()
Creating a new entry is fine, however, when I try to update any of these fields, the validation no longer passes.
创建一个新条目很好，但是，当我尝试更新这些字段中的任何一个时，验证不再通过。
The "errors" property had nothing, but I dropped into the debugger and deep within the Django guts I saw this:
“errors”属性没有任何内容，但我进入调试器并深入 Django 胆量，我看到了这一点：
slug: "Article with this None already exists"
slug：“带有此 None 的文章已经存在”
So it looks like is_valid() fails on a unique value check, but all I want to do is updatethe row.
所以看起来 is_valid() 在唯一值检查中失败，但我想要做的就是更新行。
I can't just do:
我不能只做：
form.save(force_update=True)
... because the form will fail on validation.
...因为表单将在验证时失败。
This looks like something very simple, but I just can't figure it out.
这看起来很简单，但我就是想不通。
I am running Django 1.0.2
我正在运行 Django 1.0.2
What croaks is BaseModelForm.validate_unique() which is called on form initialization.
什么是在表单初始化时调用的 BaseModelForm.validate_unique() 。
回答by Johan
I don't think you are actually updating an existing article, but instead creating a new one, presumably with more or less the same content, especially the slug, and thus you will get an error. It is a bit strange that you don't get better error reporting, but also I do not know what the rest of your view looks like.
我不认为您实际上是在更新现有文章，而是创建了一篇新文章，大概内容或多或少相同，尤其是 slug，因此您会得到错误。你没有得到更好的错误报告，这有点奇怪，但我也不知道你的视图的其余部分是什么样的。
What if you where to try something along these lines (I have included a bit more of a possible view function, change it to fit your needs); I haven't actually tested my code, so I am sure I've made at least one mistake, but you should at least get the general idea:
如果您可以按照这些方式尝试一些东西怎么办（我已经包含了更多可能的视图函数，请对其进行更改以满足您的需要）；我还没有真正测试过我的代码，所以我确定我至少犯了一个错误，但你至少应该得到一个大致的想法：
def article_update(request, id):
article = get_objects_or_404(Article, pk=id)
if request.method == 'POST':
form = ArticleForm(request.POST, instance=article)
if form.is_valid():
form.save()
return HttpResponseRedirect(to-some-suitable-url)
else:
form = ArticleForm(instance=article)
return render_to_response('article_update.html', { 'form': form })
The thing is, as taurean noted, you should instantiate your model form with the object you wish to update, otherwise you will get a new one.
事情是，正如 taurean 指出的，你应该用你想要更新的对象实例化你的模型表单，否则你会得到一个新的。
回答by mcwong
I was also searching for a way to update an existing record, even tried form.save(force_update=True)but received errors??
Finally by trial & error managed to update existing record. Below codes tested working. Hope this helps...
我也在寻找一种更新现有记录的方法，甚至尝试过form.save(force_update=True)但收到错误？最后通过反复试验设法更新现有记录。下面的代码测试工作。希望这可以帮助...
models.py from djangobook
来自 djangobook 的 models.py
class Author(models.Model):
first_name = models.CharField(max_length=30)
last_name = models.CharField(max_length=40)
email = models.EmailField(blank=True, verbose_name='e-mail')
objects = models.Manager()
sel_objects=AuthorManager()
def __unicode__(self):
return self.first_name+' '+ self.last_name
class AuthorForm(ModelForm):
class Meta:
model = Author
# views.py
# add new record
def authorcontact(request):
if request.method == 'POST':
form = AuthorForm(request.POST)
if form.is_valid():
form.save()
return HttpResponseRedirect('/contact/created')
else:
form = AuthorForm()
return render_to_response('author_form.html', {'form': form})
update existing record
更新现有记录
def authorcontactupd(request,id):
if request.method == 'POST':
a=Author.objects.get(pk=int(id))
form = AuthorForm(request.POST, instance=a)
if form.is_valid():
form.save()
return HttpResponseRedirect('/contact/created')
else:
a=Author.objects.get(pk=int(id))
form = AuthorForm(instance=a)
return render_to_response('author_form.html', {'form': form})
回答by simplyharsh
All i can guess is that you are getting an object to fill a form, and trying to save it again.
我所能猜测的是，您正在获取一个对象来填写表单，并尝试再次保存它。
Try using a ModelForm, and intantiate it with desired object.
尝试使用 ModelForm，并用所需的对象对其进行初始化。
回答by Soviut
It appears that your SlugField is returning None and because a null/blank slug already exists somewhere in the database, its giving an 'already exists' error. It seems like your slug field isn't saving correctly at all.
看来您的 SlugField 正在返回 None 并且因为空/空白 slug 已经存在于数据库中的某处，它给出了一个“已经存在”的错误。似乎您的 slug 字段根本没有正确保存。
