Django - ValidationError does not display

Hiroyuki Nuri Published at Dev

Hiroyuki Nuri

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()

miki725

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

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