better migration handling

app/migrations.py

@@ -1,9 +1,9 @@
 from .db import db
 
-# format: {integer: str|list<str>}
-MIGRATIONS = {
+# format: [str|tuple(str, any...)|callable]
+MIGRATIONS = [
 
-}
+]
 
 def run_migrations():
     db.execute("""
@@ -16,18 +16,21 @@ def run_migrations():
         return
     print("Running migrations...")
     ran = 0
-    completed = [row["id"] for row in db.query("SELECT id FROM _migrations")]
-    for migration_id in sorted(MIGRATIONS.keys()):
-        if migration_id not in completed:
-            print(f"Running migration #{migration_id}")
+    completed = {int(row["id"]) for row in db.query("SELECT id FROM _migrations")}
+    to_run = {idx: migration_obj for idx, migration_obj in enumerate(MIGRATIONS) if idx not in completed}
+    if not to_run:
+        print('No migrations need to run.')
+        return
+
+    with db.transaction():
+        for migration_id, migration_obj in to_run.items():
+            if isinstance(migration_obj, str):
+                db.execute(migration_obj)
+            elif isinstance(migration_obj, tuple):
+                db.execute(migration_obj[0], *migration_obj[1:])
+            elif callable(migration_obj):
+                migration_obj()
+
+            db.execute('INSERT INTO _migrations (id) VALUES (?)', migration_id)
             ran += 1
-            statements = MIGRATIONS[migration_id]
-            # support both strings and lists
-            if isinstance(statements, str):
-                statements = [statements]
-
-            for sql in statements:
-                db.execute(sql)
-
-            db.execute("INSERT INTO _migrations (id) VALUES (?)", migration_id)
     print(f"Ran {ran} migrations.")