poprawka zapytania

app.py

@@ -1162,17 +1162,30 @@ def get_active_months_query(visible_lists_query=None):
         month_col = func.strftime("%Y-%m", ShoppingList.created_at)
     elif db.engine.name in ("mysql", "mariadb"):
         month_col = func.date_format(ShoppingList.created_at, "%Y-%m")
-    else:  # PostgreSQL i inne wspierające to_char
+    else: #PGSQL
         month_col = func.to_char(ShoppingList.created_at, "YYYY-MM")
 
-    query = db.session.query(month_col.label("month"))
-    if visible_lists_query is not None:
-        query = query.select_from(visible_lists_query.subquery())
+    month_col = month_col.label("month")
 
-    active_months = (
-        query.filter(ShoppingList.created_at != None).distinct().order_by("month").all()
-    )
-    return [row.month for row in active_months]
+    if visible_lists_query is not None:
+        inner = (
+            db.session.query(month_col)
+            .select_from(visible_lists_query.subquery())
+            .filter(month_col.isnot(None))
+            .distinct()
+            .subquery()
+        )
+    else:
+        inner = (
+            db.session.query(month_col)
+            .select_from(ShoppingList)
+            .filter(ShoppingList.created_at.isnot(None))
+            .distinct()
+            .subquery()
+        )
+
+    rows = db.session.query(inner.c.month).order_by(inner.c.month).all()
+    return [r.month for r in rows]
 
 
 def normalize_name(name):