data_serializer_field.py

from typing import Type, TYPE_CHECKING, TypeVar

from django.utils import timezone
from rest_framework.fields import Field
from rest_framework.serializers import ListSerializer

T = TypeVar("T")


def mixin_for(_: T) -> T:
    # https://dev.to/gimntut/-1ohb
    return object


class DataSerializerField(Field):
    """Сериализатор для вычисляемых данных"""

    def __new__(
        cls, serializer: Type["SerializerType"], *args, method_name=None, **kwargs
    ) -> "SerializerType":
        class GetAttributeMixin(mixin_for(Field)):
            def get_attribute(self, instance):
                if self.source_attrs:
                    value = super().get_attribute(instance)
                else:
                    default_method_name = f"get_{self.field_name}_data"
                    attr_name = method_name or default_method_name
                    method = getattr(self.parent, attr_name, None)
                    if not method:
                        raise AttributeError(
                            f"Не найден метод {attr_name} в классе {type(self.parent).__name__}"
                        )
                    value = method(instance)
                return value

        class_name = f'{serializer.__name__.replace("Serializer", "")}DataSerializer'
        list_serializer_class = type("DataListSerializer", (GetAttributeMixin, ListSerializer), {})
        parent_meta_class = getattr(serializer, "Meta", object)
        ref_name = class_name + str(int(timezone.now().timestamp() * 100000))
        meta_class = type(
            "Meta",
            (parent_meta_class,),
            {"list_serializer_class": list_serializer_class, "ref_name": ref_name},
        )
        data_serializer_class = type(
            class_name, (GetAttributeMixin, serializer), {"Meta": meta_class}
        )
        kwargs.setdefault("source", "*")
        kwargs["read_only"] = True
        kwargs["required"] = False
        return data_serializer_class(**kwargs)


if TYPE_CHECKING:
    from utils.api.typing import SerializerType