Initial commit: Django inventory system

myproject/inventory/models.py

@@ -0,0 +1,61 @@
+from django.db import models
+from products.models import Product
+
+
+class Stock(models.Model):
+    """
+    Остатки по каждому товару.
+    """
+    product = models.OneToOneField(Product, on_delete=models.CASCADE, 
+                                  related_name='stock', verbose_name="Товар")
+    quantity_available = models.DecimalField(max_digits=10, decimal_places=3, default=0,
+                                            verbose_name="Доступное количество")
+    quantity_reserved = models.DecimalField(max_digits=10, decimal_places=3, default=0,
+                                           verbose_name="Зарезервированное количество")
+    updated_at = models.DateTimeField(auto_now=True, verbose_name="Дата обновления")
+
+    class Meta:
+        verbose_name = "Остаток на складе"
+        verbose_name_plural = "Остатки на складе"
+        indexes = [
+            models.Index(fields=['product']),
+        ]
+
+    def __str__(self):
+        return f"{self.product.name} - {self.quantity_available}"
+
+    @property
+    def quantity_free(self):
+        """Свободное количество (доступное минус зарезервированное)"""
+        return self.quantity_available - self.quantity_reserved
+
+
+class StockMovement(models.Model):
+    """
+    Журнал всех складских операций (приход, списание, коррекция).
+    """
+    REASON_CHOICES = [
+        ('purchase', 'Закупка'),
+        ('sale', 'Продажа'),
+        ('write_off', 'Списание'),
+        ('adjustment', 'Корректировка'),
+    ]
+
+    product = models.ForeignKey(Product, on_delete=models.CASCADE, 
+                               related_name='movements', verbose_name="Товар")
+    change = models.DecimalField(max_digits=10, decimal_places=3, verbose_name="Изменение")
+    reason = models.CharField(max_length=20, choices=REASON_CHOICES, verbose_name="Причина")
+    order = models.ForeignKey('orders.Order', on_delete=models.SET_NULL, null=True, blank=True,
+                             related_name='stock_movements', verbose_name="Заказ")
+    created_at = models.DateTimeField(auto_now_add=True, verbose_name="Дата создания")
+
+    class Meta:
+        verbose_name = "Движение товара"
+        verbose_name_plural = "Движения товаров"
+        indexes = [
+            models.Index(fields=['product']),
+            models.Index(fields=['created_at']),
+        ]
+
+    def __str__(self):
+        return f"{self.product.name}: {self.change} ({self.reason})"