Restructured the query to be adhering to SQLAlchemy 2.0.

Signed-off-by: Cliff Hill <Clifford.hill@gsa.gov>

app/dao/fact_notification_status_dao.py

@@ -1,9 +1,10 @@
 from datetime import date, timedelta
 
-from sqlalchemy import Date, case, func
+from sqlalchemy import Date, case, func, select, union_all, cast
 from sqlalchemy.dialects.postgresql import insert
+from sqlalchemy.orm import aliased
 from sqlalchemy.sql.expression import extract, literal
-from sqlalchemy.types import DateTime, Integer
+from sqlalchemy.types import DateTime, Integer, Text
 
 from app import db
 from app.dao.dao_utils import autocommit
@@ -126,83 +127,96 @@ def fetch_notification_status_for_service_for_day(fetch_day, service_id):
 
 
 def fetch_notification_status_for_service_for_today_and_7_previous_days(
-    service_id, by_template=False, limit_days=7
-):
+    service_id: str,
+    by_template: bool = False,
+    limit_days: int = 7
+) -> list[dict | None]:
     start_date = midnight_n_days_ago(limit_days)
     now = utc_now()
-    stats_for_7_days = db.session.query(
-        FactNotificationStatus.notification_type.cast(db.Text).label(
-            "notification_type"
-        ),
-        FactNotificationStatus.notification_status.cast(db.Text).label("status"),
+
+    # Query for the last 7 days
+    stats_for_7_days = select(
+        cast(FactNotificationStatus.notification_type, Text).label("notification_type"),
+        cast(FactNotificationStatus.notification_status, Text).label("status"),
         *(
             [
                 FactNotificationStatus.template_id.label("template_id"),
-                FactNotificationStatus.local_date.label("last_used"),
-            ]
-            if by_template
-            else []
+                FactNotificationStatus.local_date.label("date_used"),
+            ] if by_template else []
         ),
         FactNotificationStatus.notification_count.label("count"),
-    ).filter(
+    ).where(
         FactNotificationStatus.service_id == service_id,
         FactNotificationStatus.local_date >= start_date,
         FactNotificationStatus.key_type != KeyType.TEST,
     )
 
-    stats_for_today = (
-        db.session.query(
-            Notification.notification_type.cast(db.Text),
-            Notification.status.cast(db.Text),
-            *(
-                [
-                    Notification.template_id,
-                    literal(date.today()).label("last_used"),
-                ]
-                if by_template
-                else []
-            ),
-            func.count().label("count"),
-        )
-        .filter(
-            Notification.created_at >= get_midnight_in_utc(now),
-            Notification.service_id == service_id,
-            Notification.key_type != KeyType.TEST,
-        )
-        .group_by(
-            Notification.notification_type,
-            *([Notification.template_id] if by_template else []),
-            Notification.status,
-        )
+    # Query for today's stats
+    stats_for_today = select(
+        cast(Notification.notification_type, Text),
+        cast(Notification.status, Text),
+        *(
+            [
+                Notification.template_id,
+                literal(date.today()).label("date_used"),
+            ] if by_template else []
+        ),
+        func.count().label("count"),
+    ).where(
+        Notification.created_at >= get_midnight_in_utc(now),
+        Notification.service_id == service_id,
+        Notification.key_type != KeyType.TEST,
+    ).group_by(
+        Notification.notification_type,
+        *([Notification.template_id] if by_template else []),
+        Notification.status,
     )
 
-    all_stats_table = stats_for_7_days.union_all(stats_for_today).subquery()
+    # Combine the queries using union_all
+    all_stats_union = union_all(stats_for_7_days, stats_for_today).subquery()
+    all_stats_alias = aliased(all_stats_union)
 
-    query = db.session.query(
+    # Final query with optional template joins
+    query = select(
         *(
             [
                 Template.name.label("template_name"),
-                False,  # TODO: this is related to is_precompiled_letter
-                all_stats_table.c.template_id,
-                Template.folder.name.label("folder"),
-                Template.created_by.name.label("created_by"),
-            ]
-            if by_template
-            else []
+                False,  # TODO: Handle `is_precompiled_letter`
+                all_stats_alias.c.template_id,
+                Template.folder.label("folder"),
+                Template.created_by.label("created_by"),
+                func.max(all_stats_alias.c.date_used).label("last_used"),  # Get the most recent date
+            ] if by_template else []
         ),
-        all_stats_table.c.notification_type,
-        all_stats_table.c.status,
-        func.cast(func.sum(all_stats_table.c.count), Integer).label("count"),
+        all_stats_alias.c.notification_type,
+        all_stats_alias.c.status,
+        cast(func.sum(all_stats_alias.c.count), Integer).label("count"),
     )
 
     if by_template:
-        query = query.filter(all_stats_table.c.template_id == Template.id)
+        query = query.join(Template, all_stats_alias.c.template_id == Template.id)
 
-    return query.group_by(
-        *([Template.name, all_stats_table.c.template_id] if by_template else []),
-        all_stats_table.c.notification_type,
-        all_stats_table.c.status,
-    ).all()
+    # Group by all necessary fields except date_used
+    query = query.group_by(
+        *(
+            [
+                Template.name,
+                all_stats_alias.c.template_id,
+                Template.folder,
+                Template.created_by,
+            ] if by_template else []
+        ),
+        all_stats_alias.c.notification_type,
+        all_stats_alias.c.status,
+    )
+
+    print("*"*79)
+    print(query)
+    print("*"*79)
+
+    # Execute the query using Flask-SQLAlchemy's session
+    result = db.session.execute(query)
+    return result.mappings().all()
 
 
 def fetch_notification_status_totals_for_all_services(start_date, end_date):