Hi Carlos.
At first you should get an article, then put it to the form via instance
parameter. If article is not found, instance is None. Than if form is
valid, method 'save' creates new object or updates old one.
if request.method == 'POST':
try:
article = Article.objects.get(url=form.cleaned_data['url'])
except Article.DoesNotExist:
article = None
form = ArticleForm(request.POST, instance=article)
if form.is_valid():
form.save()
return redirect(reverse('articles:list'))
else:
form = ArticleForm()
return render(request, 'articles/get_article.html', {'form': form})
понедельник, 5 сентября 2016 г., 5:36:29 UTC+3 пользователь Carlos
Mermingas написал:
>
> I have a ModelForm:
>
> class ArticleForm(forms.ModelForm):
>
> class Meta:
>
> model = Article
>
> fields = ['url',]
>
>
> The Article model has a url field which is unique. I want users to enter a
> URL. If the Article already exists, it gets reused. Otherwise, a new instance
> is created.
>
>
> And the corresponding view:
>
>
> 1 @login_required
>
> 2 def get_article(request):
>
> 3 if request.method == 'POST':
>
> 4 # Should I get a new instance here?
>
> 5 form = ArticleForm(request.POST, instance=None)
>
> 6 if form.is_valid():
>
> 7 article, created =
> Article.objects.get_or_create(url=form.cleaned_data['url'])
>
> 9 # Some more work goes here
>
> 10 return redirect(reverse('articles:list'))
>
> 11 else:
>
> 12 form = ArticleForm()
>
> 13 return render(request, 'articles/get_article.html', {'form': form})
>
>
> The form is validating the uniqueness of the model, which is great. The
> dilemma I am having is that I would like to bind the form to the existing
> instance in line 4. But at that point, the form has not been cleaned, so I
> wouldn't want to hit the database with it.
>
>
> *What's the proper pattern to do this?*
>
>
> Thanks a lot!
>
>
--
You received this message because you are subscribed to the Google Groups
"Django users" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to django-users+unsubscr...@googlegroups.com.
To post to this group, send email to django-users@googlegroups.com.
Visit this group at https://groups.google.com/group/django-users.
To view this discussion on the web visit
https://groups.google.com/d/msgid/django-users/3e94ef19-a973-4ef5-b598-51a90f33aa47%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.
