seperate subjects/transaction on a user basis

core/models.py

@@ -1,7 +1,9 @@
 from decimal import Decimal
 
+from django.contrib.auth import get_user_model
 from django.db import models
-from django.utils import timezone
+
+User = get_user_model()
 
 
 class PriceField(models.DecimalField):
@@ -22,8 +24,14 @@ class PriceField(models.DecimalField):
 
 
 class Subject(models.Model):
+    class Meta:
+        unique_together = ("user", "name")
+
+    user = models.ForeignKey(
+        to=User, on_delete=models.CASCADE, editable=False,
+        related_name="subjects", related_query_name="subject",
+    )
     name = models.CharField(max_length=64)
-    created_time = models.DateTimeField(default=timezone.now)
 
     def __str__(self):
         return self.name
@@ -39,11 +47,3 @@ class Transaction(models.Model):
         to=Subject, on_delete=models.CASCADE,
         related_name="transactions", related_query_name="transaction",
     )
-
-
-class Balance(models.Model):
-    class Meta:
-        get_latest_by = "date"
-
-    amount = PriceField()
-    date = models.DateField()