forms in django, overriding validation on file upload to make sure just one value is there

Question

Edit: Mostly got this working with a clean update

I added docfile2 and docfile3 beyond the example I used to code this. I also changed the view to handle them:

 @login_required(login_url='/ngasite/login/')
def list(request):
    # Handle file upload
    if request.method == 'POST':
        form = DocumentForm(request.POST, request.FILES)
        if form.is_valid():
            for fieldname in ('docfile', 'docfile2', 'docfile3'):
                file = form.cleaned_data[fieldname]
                if file:
                    Document(docfile=file).save()


            # Redirect to the document list after POST
            return HttpResponseRedirect(reverse('ngasite:list', args=""))
    else:
        form = DocumentForm() # A empty, unbound form

    # Load documents for the list page
    documents = Document.objects.all()
    paginator = Paginator(documents, 25)
    page = request.GET.get('page')
    try:
        docs = paginator.page(page)
    except PageNotAnInteger:
        docs = paginator.page(1)
    except EmptyPage:
        docs = paginator.page(paginator.num_pages)


    # Render list page with the documents and the form
    return render_to_response(
        'ngasite/list.html',
        {'documents': documents, 'form': form, 'docs':docs},
        context_instance=RequestContext(request)
    )
This worked pretty well, I can

handle three files on my form now instead of one. But relisting after a post gives me an attribute has no file associated with it error. I am guessing because my checks for saving in the view is not really working correctly and saving regardless if there was a file or not. Maybe my python syntax is bad? no errors int he console though.

This is what is failing in my list.html template:

  {% if docs %}
                                    <ul>
                                    {% for doc in docs %}
                                        <li><a href="{{ doc.docfile.url }}">{{ doc.docfile.name }} </a></li>
                                    {% endfor %}

                                    </ul>
                                {% else %}
                                    <p>No documents.</p>
                                {% endif %}

So my real forms.py with the overriding of the is_valid

    from django import forms

 class DocumentForm(forms.Form):
    docfile = forms.FileField(
        label='Select a file',
        help_text='max. 7 Gigabytes',
        required=False
    )
    docfile2 = forms.FileField(
        label='Select a file',
        help_text='max. 7 Gigabytes',
        required=False
    )
    docfile3 = forms.FileField(
        label='Select a file',
        help_text='max. 7 Gigabytes',
        required=False
    )
    def clean(self):
        data = super(DocumentForm, self).clean()

        if not (data['docfile'] or data['docfile2'] or data['docfile3']):
            return ValidationError('You must upload at least one file.')

        return data

What am i missing? my view fails on lines like

docfile=request.FILES['docfile'] cause it knows its missing, I thought my if newdoc2: etc would handle that but it doesnt work like I think it does/should

Ultimately as I learn more python and Django i want to turn this into a nice file uploader with responses to the browser to show the upload progress etc.

Answer 1

You should set your fields to required=False, which will avoid a validation error if any field is empty:

docfile3 = forms.FileField(
    label='Select a file',
    help_text='max. 7 Gigabytes',
    required=False
)

Then in your form clean method check to see if at least one file is there:

from django.core.exceptions import ValidationError

def clean(self):
    data = super(DocumentForm, self).clean()

    # if there are already form errors, don't proceed with additional
    # validation because it may depend on fields which didn't validate.
    if self.errors:
        return data

    if not (data['docfile1'] or data['docfile2'] or data['docfile3']):
        return ValidationError('You must upload at least one file.')

    return data

I have not actually run this code so there may be some little issue but you get the idea...

In your view form_valid() method, there are problems with your saving code. Do something more like this:

for fieldname in ('docfile', 'docfile2', 'docfile3'):
    file = form.cleaned_data.get(fieldname, None)
    if file:
        Document(docfile = file).save()