def parse(self, fail_callback=None):
        """ Parse text fields and file fields for values and files """
        # get text fields
        for field in self.field_arguments:
            self.values[field['name']] = self.__get_value(field['name'])
            if self.values[field['name']] is None and field['required']:
                if fail_callback is not None:
                    fail_callback()
                self.__invalid_request(field['error'])
        # get file fields
        for file in self.file_arguments:
            self.files[file['name']] = self.__get_file(file)
            if self.files[file['name']] is None and file['required']:
                if fail_callback is not None:
                    fail_callback()
                self.__invalid_request(file['error'])
Parse text fields and file fields for values and files