def modify_content(request, page_id, content_type, language_id):
    """Modify the content of a page."""
    page = get_object_or_404(Page, pk=page_id)
    perm = request.user.has_perm('pages.change_page')
    if perm and request.method == 'POST':
        content = request.POST.get('content', False)
        if not content:
            raise Http404
        page = Page.objects.get(pk=page_id)
        if settings.PAGE_CONTENT_REVISION:
            Content.objects.create_content_if_changed(page, language_id,
                                                      content_type, content)
        else:
            Content.objects.set_or_create_content(page, language_id,
                                                  content_type, content)
        page.invalidate()
        # to update last modification date
        page.save()

        return HttpResponse('ok')
    raise Http404