django-signedforms 0.2

A signed Django form

A small library that provides a form class that signs a configurable set of hidden fields using django.core.signing.

The most common use case for such a form is when the view that handles the post differs from the view that sets up the form, but you need to pass some information from one view to the other, without evil hackers tampering with your precious data.

Usage

Subclass SignedForm, and define which fields should be signed:

from signedforms.forms import SignedForm

class MyForm(SignedForm):
    signed_fields = ['redirect_url',]

    redirect_url = forms.CharField(required=False, widget=forms.HiddenInput)

In the form that sets up the view, provide the data to be signed in the initial dictionary:

my_form = MyForm(initial={'redirect_url': self.request.path_info})

and in the view that handles the posted form:

def form_valid(self, form):
    # do some work
    return HttpResponseRedirect(form.cleaned_data['redirect_url'])

Note

If the user tampered with the hidden data, the form will not validate.

Warning

Only fields that contain JSON-serializable data can be signed. This includes all fields that are represented as text in the database, but not datetimes and other more “complex” types.