class MyFileInput(forms.FileInput):
    def render(self,name, value, attrs=None):
        output = []
        if value and hasattr(value, "url"):
            output.append('%s <a target="_blank" href="%s">%s</a> <br />%s ' % \
                (_('Actual:'), value.url, value, _('Cambio:')))
        output.append(super(MyFileInput, self).render(name, value, attrs))
        return mark_safe(u''.join(output))