add some new fields to sale item

apps/warehouse/models.py

@@ -1,6 +1,7 @@
 import string
 import random
 from apps.authentication.models import User, Organization
+from apps.pos_device.models import POSFreeProducts
 from apps.product import models as product_models
 from apps.pos_device.models import Device
 from apps.herd.models import Rancher
@@ -100,6 +101,11 @@ class InventoryQuotaSaleTransaction(BaseModel):
     )
     price_type = models.CharField(choices=type_of_price, max_length=50, null=True)
     description = models.TextField(blank=True, null=True)
+    product_type_choices = (
+        ('gov', 'government'),
+        ('free', 'free'),
+    )
+    product_type = models.CharField(max_length=20, choices=product_type_choices, default='free')
     herd_owners_number = models.PositiveBigIntegerField(default=0)
     transactions_number = models.PositiveBigIntegerField(default=0)
     status_type = (
@@ -142,12 +148,18 @@ class InventoryQuotaSaleItem(BaseModel):
         related_name='sale_items',
         null=True
     )
-    product = models.ForeignKey(
+    gov_product = models.ForeignKey(
         product_models.Product,
         on_delete=models.CASCADE,
         related_name='sale_items',
         null=True
     )
+    free_product = models.ForeignKey(
+        POSFreeProducts,
+        on_delete=models.CASCADE,
+        related_name='sale_items',
+        null=True
+    )
     image = models.CharField(max_length=150, null=True)
     name = models.CharField(max_length=150, null=True)
     price_type = models.CharField(max_length=150, null=True)
@@ -159,6 +171,10 @@ class InventoryQuotaSaleItem(BaseModel):
     is_extra = models.BooleanField(default=False)
     is_pre_sale = models.BooleanField(default=False)
 
+    @property
+    def product(self):
+        return self.gov_product or self.free_product
+
     def __str__(self):
         return f'Item {self.product} - {self.weight} Kg - {self.total_price}'