Fix(views): Add sub total to purchase summary

tienda_ilusion/don_confiao/models.py

@@ -41,6 +41,11 @@ class Sale(models.Model):
         return f"{self.date} {self.customer}"
 
 
+    def get_total(self):
+        lines = self.saleline_set.all()
+        return sum([l.quantity * l.unit_price for l in lines])
+
+
 class SaleLine(models.Model):
 
     sale = models.ForeignKey(Sale, on_delete=models.CASCADE)