- Another change to the database schema

- Enabled foreign key constraints (!!!)
- Fixed a facade bug exposed by foreign key constraints

matemat/db/facade.py

@@ -111,8 +111,12 @@ class MatematDatabase(object):
             if row is None:
                 raise ValueError(f'No user with user ID {uid} exists.')
             # Unpack the row and construct the user
-            user_id, username, email, is_admin, is_member, balance, receipt_pref = row
-            return User(user_id, username, balance, email, is_admin, is_member, ReceiptPreference(receipt_pref))
+            user_id, username, email, is_admin, is_member, balance, receipt_p = row
+            try:
+                receipt_pref: ReceiptPreference = ReceiptPreference(receipt_p)
+            except ValueError as e:
+                raise DatabaseConsistencyError(f'{receipt_p} is not a valid ReceiptPreference')
+            return User(user_id, username, balance, email, is_admin, is_member, receipt_pref)
 
     def create_user(self,
                     username: str,
@@ -531,6 +535,10 @@ class MatematDatabase(object):
         if amount < 0:
             raise ValueError('Cannot deposit a negative value')
         with self.db.transaction() as c:
+            c.execute('''SELECT username FROM users WHERE user_id = ?''',
+                      [user.id])
+            if c.fetchone() is None:
+                raise DatabaseConsistencyError(f'No such user: {user.id}')
             c.execute('''
             INSERT INTO transactions (user_id, value, old_balance)
               VALUES (:user_id, :value, :old_balance)

matemat/db/migrations.py

@@ -119,6 +119,22 @@ def migrate_schema_2_to_3(c: sqlite3.Cursor):
     # Add missing column to users table
     c.execute('ALTER TABLE users ADD COLUMN receipt_pref INTEGER(1) NOT NULL DEFAULT 0')
 
+    # Fix ON DELETE in transactions table
+    c.execute('''
+    CREATE TABLE transactions_new (
+      ta_id INTEGER PRIMARY KEY,
+      user_id INTEGER DEFAULT NULL,
+      value INTEGER(8) NOT NULL,
+      old_balance INTEGER(8) NOT NULL,
+      date INTEGER(8) DEFAULT (STRFTIME('%s', 'now')),
+      FOREIGN KEY (user_id) REFERENCES users(user_id)
+        ON DELETE SET NULL ON UPDATE CASCADE
+    )
+    ''')
+    c.execute('INSERT INTO transactions_new SELECT * FROM transactions')
+    c.execute('DROP TABLE transactions')
+    c.execute('ALTER TABLE transactions_new RENAME TO transactions')
+
     # Change modifications table
     c.execute('''
     CREATE TABLE modifications_new (

matemat/db/schemas.py

@@ -129,12 +129,12 @@ SCHEMAS[3] = [
     '''
     CREATE TABLE transactions (  -- "superclass" of the following 3 tables
       ta_id INTEGER PRIMARY KEY,
-      user_id INTEGER NOT NULL,
+      user_id INTEGER DEFAULT NULL,
       value INTEGER(8) NOT NULL,
       old_balance INTEGER(8) NOT NULL,
       date INTEGER(8) DEFAULT (STRFTIME('%s', 'now')),
       FOREIGN KEY (user_id) REFERENCES users(user_id)
-        ON DELETE CASCADE ON UPDATE CASCADE
+        ON DELETE SET NULL ON UPDATE CASCADE
     );
     ''',
     '''

matemat/db/test/test_facade.py

@@ -4,7 +4,7 @@ import unittest
 import crypt
 
 from matemat.db import MatematDatabase
-from matemat.db.primitives import User
+from matemat.db.primitives import User, ReceiptPreference
 from matemat.exceptions import AuthenticationError, DatabaseConsistencyError
 
 
@@ -24,12 +24,13 @@ class DatabaseTest(unittest.TestCase):
                 self.assertEqual('testuser@example.com', row[2])
                 self.assertEqual(0, row[5])
                 self.assertEqual(1, row[6])
+                self.assertEqual(ReceiptPreference.NONE.value, row[7])
                 with self.assertRaises(ValueError):
                     db.create_user('testuser', 'supersecurepassword2', 'testuser2@example.com')
 
     def test_get_user(self) -> None:
         with self.db as db:
-            with db.transaction(exclusive=False):
+            with db.transaction() as c:
                 created = db.create_user('testuser', 'supersecurepassword', 'testuser@example.com',
                                          admin=True, member=False)
                 user = db.get_user(created.id)
@@ -37,8 +38,14 @@ class DatabaseTest(unittest.TestCase):
                 self.assertEqual('testuser@example.com', user.email)
                 self.assertEqual(False, user.is_member)
                 self.assertEqual(True, user.is_admin)
+                self.assertEqual(ReceiptPreference.NONE, user.receipt_pref)
                 with self.assertRaises(ValueError):
                     db.get_user(-1)
+                # Write an invalid receipt preference to the database
+                c.execute('UPDATE users SET receipt_pref = 42 WHERE user_id = ?',
+                          [user.id])
+                with self.assertRaises(DatabaseConsistencyError):
+                    db.get_user(user.id)
 
     def test_list_users(self) -> None:
         with self.db as db:
@@ -166,18 +173,21 @@ class DatabaseTest(unittest.TestCase):
         with self.db as db:
             agent = db.create_user('admin', 'supersecurepassword', 'admin@example.com', True, True)
             user = db.create_user('testuser', 'supersecurepassword', 'testuser@example.com', True, True)
-            db.change_user(user, agent, email='newaddress@example.com', is_admin=False, is_member=False, balance=4200)
+            db.change_user(user, agent, email='newaddress@example.com', is_admin=False, is_member=False, balance=4200,
+                           receipt_pref=ReceiptPreference.MONTHLY)
             # Changes must be reflected in the passed user object
             self.assertEqual('newaddress@example.com', user.email)
             self.assertFalse(user.is_admin)
             self.assertFalse(user.is_member)
             self.assertEqual(4200, user.balance)
+            self.assertEqual(ReceiptPreference.MONTHLY, user.receipt_pref)
             # Changes must be reflected in the database
             checkuser = db.get_user(user.id)
             self.assertEqual('newaddress@example.com', user.email)
             self.assertFalse(checkuser.is_admin)
             self.assertFalse(checkuser.is_member)
             self.assertEqual(4200, checkuser.balance)
+            self.assertEqual(ReceiptPreference.MONTHLY, checkuser.receipt_pref)
             # Balance change without an agent must fail
             with self.assertRaises(ValueError):
                 db.change_user(user, None, balance=0)

matemat/db/wrapper.py

@@ -62,7 +62,14 @@ class DatabaseWrapper(object):
         return Transaction(self._sqlite_db, exclusive)
 
     def _setup(self) -> None:
+        # Enable foreign key enforcement
+        cursor = self._sqlite_db.cursor()
+        cursor.execute('PRAGMA foreign_keys = 1')
+
+        # Create or update schemas if necessary
         with self.transaction() as c:
+            # Defer foreign key enforcement in the setup transaction
+            c.execute('PRAGMA defer_foreign_keys = 1')
             version: int = self._user_version
             if version < 1:
                 # Don't use executescript, as it issues a COMMIT first