Django - ValidationError does not display

Question

I recently tried the forms validations and faced an issue with ValidationError().

The form error does not appear in my website when I submit the form.

Here is the code:

forms.py

class ArticleForm(forms.ModelForm):

    def clean_titre(self):
        titre = self.cleaned_data['titre']
        if len(titre) < 5:
            raise ValidationError('myError')
        return titre

form = ArticleForm()

template.html

<div class="form-group">TITRE
  {{ form.titre.errors }}
  {{ form.titre }}
</div>

views.py

def AddArticle(request):
    form = ArticleForm(request.POST, request.FILES)

    if form.is_valid():
        save_it = form.save(commit=False)
        save_it.user = request.user
        save_it.save()
        form.save_m2m()
        return HttpResponseRedirect('/')

What did I do wrong?

--- EDIT ---

Full template.html

<form class="form" action="{% url "article.views.AddArticle" %}" method="post" enctype='multipart/form-data'>
    {% csrf_token %}

    <div class="form-group">TITRE
      {{ form.titre.errors }}
      {{ form.titre }}
    </div>
    <div class="form-group">SUMMARY
      {{ form.media }}
      {{ form.summary.errors }}
      {{ form.summary }}
    </div>
    <div class="form-group">CONTENU
      {{ form.media }}
      {{ form.contenu.errors }}
      {{ form.contenu }}
    </div>
    <div class="form-group">
      {{ form.image.errors }}
      {{ form.image }}
   </div>
   <div class="form-group">TAGS
      {{ form.tags.errors }}
      {{ form.tags }}
   </div>
   <input type="submit" class="btn btn-default" value="Submit" autocomplete="off" autocorrect="off" />
</form>

I'll post the full forms.py too, it may help.

forms.py

class ArticleForm(forms.ModelForm):

    def clean_titre(self):
        titre = self.cleaned_data['titre']
        if len(titre) < 5:
            raise ValidationError('myError')
        return titre

    class Meta:
        model = Article
        exclude = ['date', 'rating', 'user']

        widgets={
            "titre":forms.TextInput(attrs={'placeholder':'Le titre', 'class':'form-control'}),
            "contenu":forms.Textarea(attrs={'placeholder':'Le Contenu de votre message', 'class':'form-control'}),
            "image":forms.FileInput(attrs={'placeholder':'Votre Image', 'id':'uploadBtn'}),
            "tags":TagWidget(attrs={'placeholder':'Vos Tags', 'class':'form-control'}),
        }

form = ArticleForm()

Where's the rest of that view? What happens if is_valid is not True? Or if it's not a POST? — Daniel Roseman
– Daniel Roseman, Commented Jul 25, 2015 at 19:46
I don't have the rest, I didn't know I needed one, what should I write it the "else:"? — Horai Nuri
– Horai Nuri, Commented Jul 25, 2015 at 19:50
In that case you would definitely get an exception, because every view must return a response. If your form is not valid but you are not getting an exception, you cannot be using this view at all. — Daniel Roseman
– Daniel Roseman, Commented Jul 25, 2015 at 19:52

miki725 · Accepted Answer · 2015-07-25 23:00:13Z

4

You are missing the else portion within your view. Here is the general flow of what forms usually do:

Users navigate to a page via GET which presents them with a form
Users fill in the form and submit it by using POST
If the form is valid, users are directed to a different page
If the form is not valid, users are presented with the same page as in step 1 with the validation errors displayed. After users correct them, they are process to step 2.

Here is that flow in django view:

def AddArticle(request):
    if request.method == 'POST':
        form = ArticleForm(request.POST, request.FILES)
        if form.is_valid():
            save_it = form.save(commit=False)
            save_it.user = request.user
            save_it.save()
            form.save_m2m()
            return HttpResponseRedirect('/')

    else:
       form = ArticleForm()

    return render(request, 'template.html', {'form': form'})

I would however look into using class based views in Django. Initially they can seem very confusing but over time you will learn to appreciate them. Docs. Another useful resource when learning CBV.

By using CBV, the above can be simplified to:

class AddArticleView(CreateView):
    success_url = 'name_of_view_here'
    form_class = ArticleForm
    template_name = 'template.html'

# urls.py
urlpatterns = patterns('', url(r'^articles/add/$', AddArticleView.as_view()))

Template

You also need to include the overall form error in the template, in addition to each field errors:

<form class="form" action="{% url "article.views.AddArticle" %}" method="post" enctype='multipart/form-data'>
    {% csrf_token %}
    {{ form.non_field_errors }}
    ...
</form>

Please note that you might need to wrap the errors with some bootstrap markup. More info in docs

edited Jul 25, 2015 at 23:00

answered Jul 25, 2015 at 20:04

miki725

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3 Comments

Daniel Roseman Over a year ago

But the mystery is that the view couldn't possibly have worked the way it is now, so there is something OP is not telling us.

miki725 Over a year ago

@Sia can you post your complete form template since currently you only posted template for a single form field

miki725 Over a year ago

not sure as well. try debugging with ipdb to verify that form is indeed invalid and that errors are present in the view. if so, then a bug is in the template. if not, then bug could with with form or view

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