database.py

@@ -2,6 +2,7 @@ from logging import Logger
 import psycopg2
 from psycopg2.extensions import connection
 from psycopg2.extras import DictCursor, DictRow
+from yoyo import get_backend, read_migrations
 from exceptions import DisplayableException
 from rss import FeedItem
 
@@ -10,12 +11,12 @@ class Database:
     """Implement interaction with the database."""
 
     def __init__(self, dsn: str, log: Logger) -> None:
-        """Create a database file if not exists."""
+        """Initialize the database"""
         self.log: Logger = log
         self.log.debug('Database.__init__(DSN=\'%s\')', dsn)
         self.conn: connection = psycopg2.connect(dsn)
         self.cur: DictCursor = self.conn.cursor(cursor_factory=DictCursor)
-        self.__init_schema()
+        self.__migrate(dsn)
 
     def add_user(self, telegram_id: int) -> int:
         """Add a user's telegram id to the database and return its database id."""
@@ -156,26 +157,14 @@ class Database:
             'INSERT INTO feeds_last_items (feed_id, url, guid) VALUES (%s, %s, %s)', new_items)
         self.conn.commit()
 
-    def __init_schema(self) -> None:
+    def __migrate(self, dsn: str) -> None:
-        self.log.debug('__init_schema()')
+        """Migrate or initialize the database schema"""
-        self.cur.execute(
+        self.log.debug(f'Database.__migrate(dsn={dsn})')
-            'CREATE TABLE IF NOT EXISTS users (id SERIAL PRIMARY KEY, telegram_id INTEGER NOT NULL UNIQUE)'
+        backend = get_backend(dsn)
-        )
+        migrations = read_migrations('./migrations')
-        self.cur.execute('CREATE TABLE IF NOT EXISTS feeds (id SERIAL PRIMARY KEY, url TEXT NOT NULL UNIQUE)')
+
-        self.cur.execute(
+        with backend.lock():
-            'CREATE TABLE IF NOT EXISTS subscriptions ('
+            backend.apply_migrations(backend.to_apply(migrations))
-            '   user_id INTEGER REFERENCES users,'
-            '   feed_id INTEGER REFERENCES feeds,'
-            '   UNIQUE (user_id, feed_id)'
-            ')'
-        )
-        self.cur.execute(
-            'CREATE TABLE IF NOT EXISTS feeds_last_items ('
-            '   feed_id INTEGER REFERENCES feeds ON DELETE CASCADE,'
-            '   url TEXT NOT NULL,'
-            '   guid TEXT'
-            ')'
-        )
 
     @staticmethod
     def __dictrow_to_dict_list(rows: list[DictRow]) -> list[dict]:

migrations/0000.initial_schema.py

@@ -0,0 +1,30 @@
+from yoyo import step
+
+steps = [
+    step(
+        'CREATE TABLE users ('
+        '   id SERIAL PRIMARY KEY,'
+        '   telegram_id INTEGER NOT NULL UNIQUE'
+        ')'
+    ),
+    step(
+        'CREATE TABLE feeds ('
+        '   id SERIAL PRIMARY KEY,'
+        '   url TEXT NOT NULL UNIQUE'
+        ')'
+    ),
+    step(
+        'CREATE TABLE subscriptions ('
+        '   user_id INTEGER REFERENCES users,'
+        '   feed_id INTEGER REFERENCES feeds,'
+        '   UNIQUE (user_id, feed_id)'
+        ')'
+    ),
+    step(
+        'CREATE TABLE feeds_last_items ('
+        '   feed_id INTEGER REFERENCES feeds ON DELETE CASCADE,'
+        '   url TEXT NOT NULL,'
+        '   guid TEXT'
+        ')'
+    )
+]

requirements.txt

@@ -13,3 +13,4 @@ six==1.16.0
 urllib3==1.26.9
 validators==0.19.0
 webencodings==0.5.1
+yoyo-migrations==7.3.2