Database format update.

Product's primary key is no longer the barcode, but a new sequential id. (products.product_id added as new column. products.bar_code no longer primary key.) Necessary foreign keys have been updated.
    Transactions have a new penalty column, and penalties applied are logged here. These are shown in the user transaction list as well.

db.py

@@ -42,7 +42,8 @@ class User(Base):
 class Product(Base):
     __tablename__ = 'products'
 
-    bar_code = Column(String(13), primary_key=True)
+    product_id = Column(Integer, primary_key=True)
+    bar_code = Column(String(13))
     name = Column(String(45))
     price = Column(Integer)
     stock = Column(Integer)
@@ -67,7 +68,7 @@ class PurchaseEntry(Base):
     __tablename__ = 'purchase_entries'
     id = Column(Integer, primary_key=True)
     purchase_id = Column(Integer,ForeignKey("purchases.id"))
-    product_bar_code = Column(String(13),ForeignKey("products.bar_code"))
+    product_id = Column(Integer,ForeignKey("products.product_id"))
     amount = Column(Integer)
 
     product = relationship(Product,backref="purchases")
@@ -90,16 +91,16 @@ class Transaction(Base):
     amount = Column(Integer)
     description = Column(String(50))
     purchase_id = Column(Integer, ForeignKey('purchases.id'))
-    #penalty = Column(Integer)
+    penalty = Column(Integer)
 
     user = relationship(User, backref=backref('transactions', order_by=time))
 
-    def __init__(self, user, amount=0, description=None, purchase=None, penalty_ratio=1):
+    def __init__(self, user, amount=0, description=None, purchase=None, penalty=1):
         self.user = user
         self.amount = amount
         self.description = description
         self.purchase = purchase
-        self.penalty = penalty_ratio
+        self.penalty = penalty
 
     def perform_transaction(self):
         self.time = datetime.datetime.now()

migration-2017-02-04.sql

@@ -0,0 +1,47 @@
+ALTER TABLE pvv_vv.products RENAME TO products_old;
+CREATE TABLE pvv_vv.products
+(
+    product_id serial,
+    bar_code character varying(13) NOT NULL,
+    name character varying(45),
+    price integer,
+    stock integer NOT NULL,
+    CONSTRAINT product_pkey PRIMARY KEY (product_id),
+    CONSTRAINT barcode_unique UNIQUE (bar_code)
+)
+
+INSERT INTO pvv_vv.products (bar_code, name, price, stock)
+    SELECT bar_code, name, price, stock FROM products_old;
+
+ALTER TABLE pvv_vv.purchase_entries RENAME TO purchase_entries_old;
+ALTER TABLE pvv_vv.purchase_entries_old
+    RENAME CONSTRAINT purchase_entries_pkey TO purchase_entries_old_pkey;
+ALTER TABLE pvv_vv.purchase_entries_old
+    RENAME CONSTRAINT purchase_entries_purchase_id_fkey TO purchase_entries_old_purchase_id_fkey;
+ALTER TABLE pvv_vv.purchase_entries_old
+    RENAME CONSTRAINT purchase_entries_product_bar_code_fkey TO purchase_entries_old_product_bar_code_fkey;
+
+CREATE TABLE pvv_vv.purchase_entries
+(
+    id serial,
+    purchase_id integer,
+    product_id integer,
+    amount integer,
+    CONSTRAINT purchase_entries_pkey PRIMARY KEY (id),
+    CONSTRAINT purchase_entries_product_id_fkey FOREIGN KEY (product_id)
+        REFERENCES pvv_vv.products (product_id) MATCH SIMPLE
+        ON UPDATE NO ACTION
+        ON DELETE NO ACTION,
+    CONSTRAINT purchase_entries_purchase_id_fkey FOREIGN KEY (purchase_id)
+        REFERENCES pvv_vv.purchases (id) MATCH SIMPLE
+        ON UPDATE NO ACTION
+        ON DELETE NO ACTION
+);
+INSERT INTO purchase_entries (id, purchase_id, product_id, amount)
+    SELECT peo.id, peo.purchase_id, p.product_id, peo.amount
+        FROM purchase_entries_old AS peo
+            JOIN products AS p ON p.bar_code = peo.product_bar_code;
+ALTER TABLE pvv_vv.transactions
+    ADD COLUMN penalty integer DEFAULT 1;
+DROP TABLE products_old;
+DROP TABLE purchase_entries_old;

text_based.py

@@ -787,8 +787,8 @@ class ShowUserMenu(Menu):
                 string += ', '.join(map(lambda e: e.product.name,
                                         t.purchase.entries))
                 string += ')'
-                #if t.penalty > 1:
+                if t.penalty > 1:
-                #    string += ' * %dx penalty applied' % t.penalty
+                    string += ' * %dx penalty applied' % t.penalty
             else:
                 string += t.description
             string += '\n'
@@ -810,8 +810,8 @@ class ShowUserMenu(Menu):
                 string += ', '.join(map(lambda e: e.product.name,
                                         t.purchase.entries))
                 string += ')'
-                #if t.penalty > 1:
+                if t.penalty > 1:
-                #    string += ' * %dx penalty applied' % t.penalty
+                    string += ' * %dx penalty applied' % t.penalty
             else:
                 string += t.description
             string += '\n'
@@ -927,7 +927,7 @@ When finished, write an empty line to confirm the purchase.
 
             if not self.credit_check(thing):
                 if self.low_credit_warning(user=thing, timeout=self.superfast_mode):
-                    Transaction(thing, purchase=self.purchase, penalty_ratio=2)
+                    Transaction(thing, purchase=self.purchase, penalty=2)
                 else:
                     return False
             else: