How to use a redirect with Form builder to prevent double submission¶
It is common for form submission HTTP responses to be a 302 Found
temporary redirection to a new page.
By default wagtail.contrib.forms.models.FormPage
success responses don’t do this, meaning there is a risk that users will refresh the success page and re-submit their information.
Instead of rendering the render_landing_page
content in the POST response, we will redirect to a route
of the FormPage
instance at a child URL path.
The content will still be managed within the same form page’s admin.
This approach uses the additonal contrib module wagtail.contrib.routable_page
.
An alternative approach is to redirect to an entirely different page, which does not require the routable_page
module.
See Custom landing page redirect.
Make sure "wagtail.contrib.routable_page"
is added to INSTALLED_APPS
, see Installation documentation.
from django.shortcuts import redirect
from wagtail.contrib.forms.models import AbstractEmailForm
from wagtail.contrib.routable_page.models import RoutablePageMixin, route
class FormPage(RoutablePageMixin, AbstractEmailForm):
# fields, content_panels, …
@route(r"^$")
def index_route(self, request, *args, **kwargs):
"""Serve the form, and validate it on POST"""
return super(AbstractEmailForm, self).serve(request, *args, **kwargs)
def render_landing_page(self, request, form_submission, *args, **kwargs):
"""Redirect instead to self.thank_you route"""
url = self.reverse_subpage("thank_you")
# If a form_submission instance is available, append the ID to URL.
if form_submission:
url += "?id=%s" % form_submission.id
return redirect(self.url + url, permanent=False)
@route(r"^thank-you/$")
def thank_you(self, request):
"""Return the superclass's landing page, after redirect."""
form_submission = None
try:
submission_id = int(request.GET["id"])
except (KeyError, TypeError):
pass
else:
submission_class = self.get_submission_class()
try:
form_submission = submission_class.objects.get(id=submission_id)
except submission_class.DoesNotExist:
pass
return super().render_landing_page(request, form_submission)