Added related name and showing read only item details in invoice list

invoice/models.py

@@ -1,5 +1,6 @@
 from django.db import models
 from project.models import Project
+from client.models import Client, Address, TaxType
 
 
 class Invoice(models.Model):
@@ -19,6 +20,18 @@ class Invoice(models.Model):
             total += item.item_total
         return total
 
+    @property
+    def invoice_total_after_tax(self):
+        items = Item.objects.filter(invoice=self.pk)
+        project = Project.objects.get(client=self.project)
+        client = Client.objects.get(pk=project.client)
+        address = Address.objects.get(pk=client.address)
+        tax_type = TaxType.objects.get(pk=address.tax_type)
+        total = 0
+        for item in items:
+            total += item.item_total
+        return total
+
     def __str__(self):
         return self.invoice_id
 
@@ -27,7 +40,7 @@ class Item(models.Model):
     name = models.TextField(blank=False, null=False)
     amount = models.DecimalField(max_digits=15, decimal_places=2)
     quantity = models.IntegerField()
-    invoice = models.ForeignKey(Invoice, on_delete=models.CASCADE)
+    invoice = models.ForeignKey(Invoice, on_delete=models.CASCADE, related_name='items')
 
     @property
     def item_total(self):

invoice/serializers.py

@@ -9,6 +9,9 @@ class ItemSerializer(serializers.ModelSerializer):
 
 
 class InvoiceSerializer(serializers.ModelSerializer):
+    items = ItemSerializer(many=True, read_only=True)
+
     class Meta:
         model = Invoice
-        fields = ['id', 'title', 'project', 'invoice_id', 'raised_date', 'due_date', 'paid_date', 'is_archived', 'invoice_total']
+        fields = ['id', 'title', 'project', 'invoice_id', 'raised_date', 'due_date', 'paid_date', 'is_archived',
+                  'invoice_total', 'items']