Source code for services.posts.category

from typing import List

from django.db.models import QuerySet

from apps.posts.models import Post
from apps.users.models import Category
from core.settings import POSTS_CONFIGS
from services.posts.exceptions import CategoriesDontExistException, TooManyCategoriesException




class PostCategoryService:
    @classmethod
    def _validate_categories(cls, categories_ids: List[int]) -> QuerySet[Category]:
        categories = Category.objects.filter(pk__in=categories_ids)
        max_categories = POSTS_CONFIGS.get("MAX_POST_CATEGORIES", 1)
        if not categories.exists():
            raise CategoriesDontExistException
        if categories.count() > max_categories:
            raise TooManyCategoriesException
        return categories



    @classmethod
    def set_categories(cls, post: Post, categories_ids: List[int]) -> None:
        """
        Set categories list to post instance after validation
        :param post: Post instance
        :param categories_ids: categories id list
        """
        categories = cls._validate_categories(categories_ids)
        # Check is category was changed
        if categories.values_list("pk", flat=True) != post.categories.values_list("pk", flat=True):
            post.categories.set(categories)