@classmethod
def get_field_name_to_field(cls):
    """
        Returns dictionary with fieldnames defined in searchset class and field instances
        """
    if cls._field_name_to_search_field_instance is None:
        cls._field_name_to_search_field_instance = dict()
        cls._field_source_to_search_field_instance = dict()
        for name, _cls in cls.__dict__.items():
            if isinstance(_cls, cls._field_base_class):
                cls._field_name_to_search_field_instance[name] = _cls
                if (_cls.use_field_class_for_sources and not _cls.
                    exclude_sources_from_mapping and _cls.sources):
                    for field_source in _cls.sources:
                        cls.append_field_source_to_search_field_instance(source
                            =field_source, instance=_cls.__class__())
    return cls._field_name_to_search_field_instance
