Django form not calling custom validator

Question

I'm using Django 2.0. This is my forms.py:

class PostcodeForm(forms.Form):
    postcode = forms.CharField(required=True, widget=forms.TextInput(
        attrs={
            'placeholder': "enter a postcode",
        }
    ))

    def clean_postcode(self):
        postcode = self.clean_data.get('postcode', '')
        print('clean_postcode', postcode)
        if postcode != 'something':
            raise forms.ValidationError(_("Please enter a valid postcode"), code='invalid')
        return data

And my views.py:

def index(request):
    form = PostcodeForm()
    context = {
        'form': form
    }
    return render(request, 'index.html', context)

And my index.html:

<form class="form-inline" id="lookup_postcode" action="{% url 'lookup_postcode' %}" method="get">
    {% csrf_token %}
    {{ form.non_field_errors }}
    {{ form.postcode.errors }}
    {{ form.postcode }}
    <button type="submit">Submit</button>
</form>

But when I type in any value other than 'something', the form still submits. I also don't see any print statements in the console, so it looks as though the validator just isn't being run.

What am I doing wrong?

Can you show the code of the view you are calling through the url "lookup_postcode"? — jantoniomartin
– jantoniomartin, Commented Apr 12, 2018 at 10:00
you have used self.clean_data in form is it typo?? I believe you need to use self.cleaned_data and what's the data you returned with return data — Gahan
– Gahan, Commented Apr 12, 2018 at 10:02

Alasdair · Accepted Answer · 2018-04-12 10:06:07Z

5

At the moment you are always doing form = PostcodeForm(), for GET and POST requests. That means that the form is not bound to any data, so it will never be valid or have any errors.

In Django, a typical view to process a form looks something like this:

from django.shortcuts import redirect

def index(request):
    if request.method == 'POST':
        form = PostcodeForm(request.POST)
        if form.is_valid():
            # form is valid. Process form and redirect
            ...
            return redirect('/success-url/')
    else:
        form = PostcodeForm()
    context = {
        'form': form
    }
    return render(request, 'index.html', context)

For this to work, you'll need to change your form method to 'post'.

<form class="form-inline" id="lookup_postcode" action="{% url 'lookup_postcode' %}" method="post">

If you keep the form method as 'get' then you'll need to bind the form to request.GET instead. You might want to add a check, otherwise you'll get errors for required fields when you first access the index view.

if 'postcode' in request.GET:
    # bound form
    form = PostcodeForm(request.GET)
else:
    # unbound, empty form
    form = PostcodeForm()

edited Apr 12, 2018 at 10:06

answered Apr 12, 2018 at 10:00

Alasdair

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1 Comment

Richard Over a year ago

Thanks! For the benefit of others, I used form.add_error() to add custom errors as required.

Gahan · Accepted Answer · 2018-04-12 10:04:05Z

0

Use your form as below:

class PostcodeForm(forms.Form):
    postcode = forms.CharField(required=True, widget=forms.TextInput(
        attrs={
            'placeholder': "enter a postcode",
        }
    ))

    def clean(self):
        postcode = self.cleaned_data.get('postcode', '')
        print('clean_postcode', postcode)
        if postcode != 'something':
            raise forms.ValidationError(_("Please enter a valid postcode"), code='invalid')
        return super(PostcodeForm, self).clean()

answered Apr 12, 2018 at 10:04

Gahan

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Comments

user8817894 · Accepted Answer · 2018-04-12 10:04:53Z

0

Everytime you deal with the validity of the posted data, make sure to include form.is_valid() condition in your views.py.

answered Apr 12, 2018 at 10:04

user8817894

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