Fix Laundry Snapshot Collection (#225)

backend/laundry/views.py

@@ -2,9 +2,9 @@
 import datetime
 
 from django.core.cache import cache
+from django.db.models import Q
 from django.shortcuts import get_object_or_404
 from django.utils import timezone
-from django.utils.timezone import make_aware
 from requests.exceptions import HTTPError
 from rest_framework.permissions import IsAuthenticated
 from rest_framework.response import Response
@@ -64,29 +64,21 @@ def safe_division(a, b):
         return round(a / float(b), 3) if b > 0 else 0
 
     def get_snapshot_info(hall_id):
-        now = timezone.localtime()
-
-        # start is beginning of day, end is 27 hours after start
-        start = make_aware(datetime.datetime(year=now.year, month=now.month, day=now.day))
-        end = start + datetime.timedelta(hours=27)
-
         # filters for LaundrySnapshots within timeframe
         room = get_object_or_404(LaundryRoom, hall_id=hall_id)
 
-        snapshots = LaundrySnapshot.objects.filter(room=room, date__gt=start, date__lte=end)
+        # get start time, which is now without the times
+        start = timezone.localtime().replace(hour=0, minute=0, second=0, microsecond=0)
 
         # adds all the LaundrySnapshots from the same weekday within the previous 28 days
-        for week in range(1, 4):
-            # new_start is beginning of day, new_end is 27 hours after start
+        filter = Q()
+        for week in range(4):
             new_start = start - datetime.timedelta(weeks=week)
             new_end = new_start + datetime.timedelta(hours=27)
+            filter |= Q(room=room, date__gt=new_start, date__lt=new_end)
 
-            new_snapshots = LaundrySnapshot.objects.filter(
-                room=room, date__gt=new_start, date__lte=new_end
-            )
-            snapshots = snapshots.union(new_snapshots)
-
-        return (room, snapshots.order_by("-date"))
+        snapshots = LaundrySnapshot.objects.filter(filter).order_by("-date")
+        return (room, snapshots)
 
     def compute_usage(hall_id):
         try:
@@ -103,13 +95,8 @@ def compute_usage(hall_id):
 
         for snapshot in snapshots:
             date = snapshot.date.astimezone()
-
-            if date < min_date:
-                min_date = date
-
-            if date > max_date:
-                max_date = date
-
+            min_date = min(min_date, date)
+            max_date = max(max_date, date)
             hour = date.hour
 
             # accounts for the 3 hours on the next day
@@ -132,8 +119,12 @@ def compute_usage(hall_id):
             "day_of_week": calendar.day_name[timezone.localtime().weekday()],
             "start_date": min_date.date(),
             "end_date": max_date.date(),
-            "washer_data": {x: HallUsage.safe_division(data[x][0], data[x][2]) for x in range(27)},
-            "dryer_data": {x: HallUsage.safe_division(data[x][1], data[x][2]) for x in range(27)},
+            "washer_data": {
+                x: HallUsage.safe_division(data[x][0], data[x][2]) for x in range(len(data))
+            },
+            "dryer_data": {
+                x: HallUsage.safe_division(data[x][1], data[x][2]) for x in range(len(data))
+            },
             "total_number_of_washers": room.total_washers,
             "total_number_of_dryers": room.total_dryers,
         }