Coverage for src/shopping_bags/services.py: 93%

1from rest_framework.exceptions import ValidationError 

2 

3from src.shopping_bags.models import ShoppingBag 

4from src.common.services import UserIdentificationService 

5from src.shopping_bags.constants import ShoppingBagErrorMessages 

6 

7 

8class ShoppingBagService: 

9 """ 

10 This class encapsulates all business logic related to shopping bag functionality, 

11 including user identification, inventory validation, and quantity management. 

12 

13 Key Responsibilities: 

14 - Inventory object retrieval and validation 

15 - Stock quantity validation 

16 - Atomic database operations for inventory updates 

17 - Shopping bag item creation and retrieval 

18 """ 

19 

20 @staticmethod 

21 def get_user_identifier(request): 

22 return UserIdentificationService.get_user_identifier(request) 

23 

24 @staticmethod 

25 def validate_inventory_quantity(inventory_obj, required_quantity): 

26 if required_quantity > inventory_obj.quantity: 

27 raise ValidationError( 

28 { 

29 'quantity': ShoppingBagErrorMessages.INSUFFICIENT_STOCK.format( 

30 quantity=inventory_obj.quantity 

31 ) 

32 } 

33 ) 

34 

35 @staticmethod 

36 def get_or_create_bag_item(filters, defaults): 

37 return ShoppingBag.objects.get_or_create(**filters, defaults=defaults)