handle multiple products and handling errors, using atomicity need

StockSeeker/serializers.py

@@ -2,7 +2,7 @@ from rest_framework import serializers
 from .models import *
 from django.contrib.auth.models import User
 from django.db.models import F
-
+from django.db import transaction
 class UserSerializer(serializers.ModelSerializer):
     password = serializers.CharField(write_only=True)
 
@@ -50,38 +50,51 @@ class ProductSerializer(serializers.ModelSerializer):
         model = Product
         fields = ["id", "name", "description", "quantity", "creation_date", "modification_date", "user","stock_limit","alert_enabled","is_stock_low","image","warehouses",]
 
-    #GERER les nombres négatifs impossible #
     def create(self, validated_data):
         warehouses = validated_data.pop('warehouses', [])
-        product = Product.objects.create(**validated_data)
-        product.warehouses.set(warehouses)
+        
+        with transaction.atomic():
+            product = Product.objects.create(**validated_data)
+            product.warehouses.set(warehouses)
 
-        for warehouse in product.warehouses.all():
-            warehouse.actual_capacity = F('actual_capacity') - product.quantity
-            warehouse.save(update_fields=['actual_capacity'])
+            for warehouse in product.warehouses.all():
+                warehouse.refresh_from_db()
+                if warehouse.actual_capacity - product.quantity < 0:
+                    raise serializers.ValidationError({
+                        'quantity': ["L'entrepôt n'a plus assez de place"]
+                    })
+                warehouse.actual_capacity = F('actual_capacity') - product.quantity
+                warehouse.save(update_fields=['actual_capacity'])
 
         return product
     
     def update(self,instance, validated_data):
-        instance.name = validated_data.get("name", instance.name)
-        instance.description = validated_data.get("description", instance.description)
         new_quantity = validated_data.get("quantity", instance.quantity)
-
         quantity_difference = new_quantity - instance.quantity
-        instance.quantity = new_quantity
-        instance.save()
-        instance.refresh_from_db()
 
-        for warehouse in instance.warehouses.all():
-            warehouse.actual_capacity = F('actual_capacity') - quantity_difference
-            warehouse.save(update_fields=['actual_capacity'])
-        return instance
+        with transaction.atomic():
+            instance.name = validated_data.get("name", instance.name)
+            instance.description = validated_data.get("description", instance.description)
+            instance.quantity = new_quantity
+            instance.save()
+
+            for warehouse in instance.warehouses.all():
+                warehouse.refresh_from_db()
+                if warehouse.actual_capacity - quantity_difference < 0:
+                    raise serializers.ValidationError({
+                        'quantity': ["L'entrepôt n'a plus assez de place"]
+                    })
+                warehouse.actual_capacity = F('actual_capacity') - quantity_difference
+                warehouse.save(update_fields=['actual_capacity'])
+            return instance
     
     def destroy(self, instance):
-        for warehouse in instance.warehouses.all():
-            warehouse.actual_capacity = F('actual_capacity') + instance.quantity
-            warehouse.save(update_fields=['actual_capacity'])
-        instance.delete()
+        with transaction.atomic():
+            for warehouse in instance.warehouses.all():
+                warehouse.refresh_from_db()
+                warehouse.actual_capacity = F('actual_capacity') + instance.quantity
+                warehouse.save(update_fields=['actual_capacity'])
+            instance.delete()
     
     def validate_warehouses(self, value):
         if not value:
@@ -102,16 +115,25 @@ class WarehouseSerializer(serializers.ModelSerializer):
 
     def update(self, instance, validated_data):
         old_max_capacity = instance.max_capacity
-        instance.name = validated_data.get("name", instance.name)
-        instance.location = validated_data.get("location", instance.location)
-        new_max_capacity = validated_data.get("max_capacity", instance.max_capacity)
-        capacity_difference = new_max_capacity - old_max_capacity
 
-        instance.actual_capacity = F('actual_capacity') + capacity_difference
-        instance.max_capacity = new_max_capacity
+        with transaction.atomic():
+            instance.name = validated_data.get("name", instance.name)
+            instance.location = validated_data.get("location", instance.location)
+            new_max_capacity = validated_data.get("max_capacity", instance.max_capacity)
 
-        instance.save()
-        instance.refresh_from_db()
+            capacity_difference = new_max_capacity - old_max_capacity
+
+            new_actual_capacity = instance.actual_capacity + capacity_difference
+            if new_actual_capacity < 0:
+                raise serializers.ValidationError({
+                    'max_capacity': ["La réduction de la capacité maximale entraînerait une capacité actuelle négative."]
+                })
+
+            instance.actual_capacity = F('actual_capacity') + capacity_difference
+            instance.max_capacity = new_max_capacity
+
+            instance.save()
+            instance.refresh_from_db()
 
         return instance
     
@@ -119,6 +141,9 @@ class WarehouseSerializer(serializers.ModelSerializer):
         model = Warehouse
         fields = ["id", "name", "location", "max_capacity","user","actual_capacity"]
     
+    def create(self, validated_data):
+        validated_data["actual_capacity"] = validated_data.get("max_capacity",0)
+        return Warehouse.objects.create(**validated_data)
     
     def validate_max_capacity(self, value):
         if value < 0: