0
votes

I am currently going through the Tango with Django tutorial, finishing up Chapter 8: http://www.tangowithdjango.com/book17/chapters/forms.html

I finally got everything to work, the last issue I have is the add_page form's handling of a url that did not start with 'http://', and I'm not quite sure why. No errors arise with the actual web app, I simply get the "Please enter URL" tool-tip window if I do not include it in the URL, and processes correctly once I add in the 'http://' myself.

These are my files:

#VIEWS.PY

from django.http import HttpResponse
from django.shortcuts import render
from rango.models import Category
from rango.models import Page
from rango.forms import CategoryForm
from rango.forms import PageForm

def index(request):
    # Query the database for a list of ALL categories currently stored.
    # Order the categories by no. likes in descending order.
    # Retrieve the top 5 only - or all if less than 5.
    # Place the list in our context_dict and dictionary which will be passed to the template engine.
    category_list = Category.objects.order_by('-likes')[:5]
    page_list = Page.objects.order_by('-views')[:5]
    context_dict = {'categories': category_list, 'pages': page_list}

    # Render the response and send it back!
    return render(request, 'rango/index.html', context_dict)

def about(request):
    context_dict = {'italicmessage': "I am italicised font from the context"}
    return render(request, 'rango/about.html', context_dict)

def category(request, category_name_slug):

    # Create a context dictionary which we can pass to the template rendering engine
    context_dict = {}

    try:
        # Can we find a category name slug with the given name?
        # If we can't, the .get() method raises a DoesNotExist exception.
        # So the .get() method returns one model instance or raises an exception.
        category = Category.objects.get(slug=category_name_slug)
        context_dict['category_name'] = category.name

        # Retrieve all the associated pages.
        # Note that filter returns >= 1 model instance.
        pages = Page.objects.filter(category=category)

        # Adds our results list to the template context under name pages.
        context_dict['pages'] = pages
        # We also add the category object from the database to the context dictionary.
        # We'll use this in the template to verify that the category exists.
        context_dict['category'] = category
        context_dict['category_name_slug'] = category_name_slug

    except Category.DoesNotExist:
        # We get here if we didn't find the specified category.
        # Don't do anything - the template displayes the "no category message for us."
        pass

    # Go render the response and return it to the client.
    return render(request, 'rango/category.html', context_dict)

def add_category(request):
    # A HTTP POST?
    if request.method == 'POST':
        form = CategoryForm(request.POST)

        # Have we been provided with a valid form?
        if form.is_valid():
            # save the new category to the database.
            form.save(commit=True)

            # Now call the index() view.
            # The user will be shown the homepage.
            return index(request)
        else:
            # The supplied form contained errors - just print them to the terminal.
            print form.errors
    else:
        # If the request was not a POST, display the form to enter details.
        form = CategoryForm()

    # Bad form (or form details), no form supplied...
    # Render the form with error messages (if any).
    return render(request, 'rango/add_category.html', {'form': form})

def add_page(request, category_name_slug):

    try:
        cat = Category.objects.get(slug=category_name_slug)
    except Category.DoesNotExist:
        cat = None

    if request.method == 'POST':
        form = PageForm(request.POST)
        if form.is_valid():
            if cat:
                page = form.save(commit=False)
                page.category = cat
                page.views = 0
                page.save()
                return category(request, category_name_slug)
    else:
        form = PageForm()

    context_dict = {'form': form, 'category': cat, 'category_name_slug': category_name_slug}

    return render(request, 'rango/add_page.html', context_dict)

And...

# FORMS.PY

from django import forms
from rango.models import Page, Category

class CategoryForm(forms.ModelForm):
    name = forms.CharField(max_length=128, help_text="Please enter the category name.")
    views = forms.IntegerField(widget=forms.HiddenInput(), initial=0)
    likes = forms.IntegerField(widget=forms.HiddenInput(), initial=0)
    slug = forms.CharField(widget=forms.HiddenInput(), required=False)

    # An inline class to provide additional information on the form.
    class Meta:
        # Provide an association between the ModelForm and a model
        model = Category
        fields = ('name',)

class PageForm(forms.ModelForm):
    title = forms.CharField(max_length=128, help_text="Please enter the title of the page.")
    url = forms.URLField(max_length=200, help_text="Please enter the URL of the page.")
    views = forms.IntegerField(widget=forms.HiddenInput(), initial=0)

    class Meta:
        model = Page
        exclude = ('category',)
                # or specify the fields to include (.i.e. not include the category field)
        #fields = ('title', 'url', 'views')

    def clean(self):
        cleaned_data = self.cleaned_data
        url = cleaned_data.get('url')

        # If url is not empty and doesn't start with 'http://', prepend 'http://'.
        if url and not url.startswith('http://'):
            url = 'http://' + url
            cleaned_data['url'] = url

        return cleaned_data

I suspect it is something with my PageForm class in forms.py, but I seem to have just replicated the code as shown in the tutorial.

Thanks in advance for your help!

3

3 Answers

2
votes

A quick look at the Django source shows why this happens:

in core/validators.py

class URLField(CharField):
    default_validators = [validators.URLValidator()]
    description = _("URL")

You see the default validator for URLField is the URLValidator which can be found in core/validators.py:

@deconstructible
class URLValidator(RegexValidator):
    regex = re.compile(
        r'^(?:[a-z0-9\.\-]*)://'  # scheme is validated separately
        r'(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}(?<!-)\.?)|'  # domain...
        r'localhost|'  # localhost...
        r'\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}|'  # ...or ipv4
        r'\[?[A-F0-9]*:[A-F0-9:]+\]?)'  # ...or ipv6
        r'(?::\d+)?'  # optional port
        r'(?:/?|[/?]\S+)$', re.IGNORECASE)
    message = _('Enter a valid URL.')
    schemes = ['http', 'https', 'ftp', 'ftps']

    def __init__(self, schemes=None, **kwargs):
        super(URLValidator, self).__init__(**kwargs)
        if schemes is not None:
            self.schemes = schemes

    def __call__(self, value):
        value = force_text(value)
        # Check first if the scheme is valid
        scheme = value.split('://')[0].lower()
        if scheme not in self.schemes:
            raise ValidationError(self.message, code=self.code)

        # Then check full URL
        try:
            super(URLValidator, self).__call__(value)
        except ValidationError as e:
            # Trivial case failed. Try for possible IDN domain
            if value:
                scheme, netloc, path, query, fragment = urlsplit(value)
                try:
                    netloc = netloc.encode('idna').decode('ascii')  # IDN -> ACE
                except UnicodeError:  # invalid domain part
                    raise e
                url = urlunsplit((scheme, netloc, path, query, fragment))
                super(URLValidator, self).__call__(url)
            else:
                raise
        else:
            url = value

So as you can see here if the url prefix is not found in schemes then your URLField won't validate. Specifically in __call__ it splits the supplied input with scheme = value.split('://')[0].lower() to get the prefix. Your best bet is to create your own custom validation if you don't want to use this one. You might want to read: https://docs.djangoproject.com/en/dev/ref/forms/validation/ for more information.

1
votes

Thats because you work with that url form field ... If you want pass a URL without http:// then you can take a normal char Form field

Behind that URL field is a validation, you can change that validation when you want to work with an URL field

Hope that helps

1
votes

An URLField uses URLValidator for validation. From it's source:

scheme = value.split('://')[0].lower()
if scheme not in self.schemes:
    raise ValidationError(self.message, code=self.code)

and per default:

schemes = ['http', 'https', 'ftp', 'ftps']

So obviously, only absolute URLs are allowed.

See also this rejected feature request.