added 'unique' attribute to some fields

cash/models.py

@@ -3,23 +3,23 @@ from django.contrib.auth.models import User
 
 class Account(models.Model):
 	user = models.OneToOneField(User)
-	card_number = models.CharField(max_length=32)
+	card_number = models.CharField(max_length=32, unique=True)
 	pin = models.CharField(max_length=32)
 	daily_digest = models.BooleanField()
 	credit = models.IntegerField()
 
 class ProductCategory(models.Model):
-	name = models.CharField(max_length=32)
+	name = models.CharField(max_length=32, unique=True)
 	comment = models.CharField(max_length=128, blank=True)
 
 class Product(models.Model):
-	name = models.CharField(max_length=32)
+	name = models.CharField(max_length=32, unique=True)
 	price = models.IntegerField()
 	deleted = models.BooleanField()
 	category = models.ForeignKey(ProductCategory, blank=True, null=True)
 
 class ProductBarcode(models.Model):
-	barcode = models.CharField(max_length=32)
+	barcode = models.CharField(max_length=32, unique=True)
 	comment = models.CharField(max_length=128)
 	product = models.ForeignKey(Product)
 
@@ -31,7 +31,7 @@ class Transaction(models.Model):
 	amount = models.IntegerField()
 
 class SalesLogEntry(models.Model):
-	account = models.ForeignKey(Account)	
+	account = models.ForeignKey(Account)
 	product = models.ForeignKey(Product)
 	count = models.IntegerField()
 	unit_price = models.IntegerField()