def updateWidgets(self): super(FieldAddForm, self).updateWidgets() fieldset_id = int(self.request.form.get('fieldset_id', 0)) if fieldset_id: # add fieldset_id from GET parameter as hidden field, so that # ``add`` method at the end of the form lifecycle can read it. fieldset_id_widget = TextWidget(self.request) fieldset_id_widget.name = 'fieldset_id' fieldset_id_widget.value = fieldset_id fieldset_id_widget.mode = HIDDEN_MODE # Uhm. z3c.form widgets doesn't have an API for extending a # schema-generated form. Using internal ``_data_values``... self.widgets._data_values.append(fieldset_id_widget)