add: order model, order create api, order create serializer, order item model

core/apps/orders/models/__init__.py

@@ -0,0 +1 @@
+from .order import *

core/apps/orders/models/order.py

@@ -0,0 +1,31 @@
+from django.db import models
+
+from core.apps.shared.models import BaseModel
+from core.apps.accounts.models import User
+from core.apps.products.models import Product
+
+
+class Order(BaseModel):
+    total_price = models.PositiveBigIntegerField(default=0)
+    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='orders') 
+
+    def __str__(self):
+        return f'{self.user} order'
+
+    class Meta:
+        verbose_name = 'Buyurtma'
+        verbose_name_plural = 'Buyurtmalar'
+        
+
+class OrderItem(BaseModel):
+    order = models.ForeignKey(Order, on_delete=models.CASCADE, related_name='items')
+    quantity = models.PositiveIntegerField()
+    price = models.PositiveBigIntegerField()
+    product = models.ForeignKey(Product, on_delete=models.CASCADE, related_name='items', null=True)
+
+    def __str__(self):
+        return f'{self.quantity} - {self.price} to {self.order}'
+    
+    class Meta:
+        verbose_name = 'Buyurtma elementi'
+        verbose_name_plural = 'Buyurtma elementlari'