implement command to clean old values from the database

sensors/collector/collector.py

@@ -1,5 +1,5 @@
 import os
-from datetime import datetime
+from datetime import datetime, timedelta
 
 if os.uname()[4].startswith("arm"):
     from sense_hat import SenseHat
@@ -31,3 +31,10 @@ def values_to_db():
     Temperature.objects.create(value=get_temperature(), time=time)
     Humidity.objects.create(value=get_humidity(), time=time)
     Pressure.objects.create(value=get_pressure(), time=time)
+
+
+def clean_db():
+    time = datetime.now() - timedelta(days=30)
+    Temperature.objects.filter(time__lt=time).delete()
+    Humidity.objects.filter(time__lt=time).delete()
+    Pressure.objects.filter(time__lt=time).delete()

sensors/collector/management/commands/clean.py

@@ -0,0 +1,8 @@
+from django.core.management.base import BaseCommand, CommandError
+from collector.collector import clean_db
+
+class Command(BaseCommand):
+    help = 'Clean out values older than 30 days.'
+
+    def handle(self, *args, **options):
+        clean_db()

sensors/collector/tests/test_collector.py

@@ -1,4 +1,6 @@
+from datetime import datetime, timedelta
 import pytest
+from mixer.backend.django import mixer
 
 from collector import collector
 from collector.models import Temperature, Humidity, Pressure
@@ -52,3 +54,28 @@ def test_values_to_db(monkeypatch):
     assert (temp.value == 25.5
             and humidity.value == 45
             and pressure.value == 1013)
+
+
+def test_clean_db_remove_values():
+    old_time = datetime.now() - timedelta(days=30)
+    mixer.blend('collector.Temperature', time=old_time)
+    mixer.blend('collector.Pressure', time=old_time)
+    mixer.blend('collector.Humidity', time=old_time)
+    collector.clean_db()
+    temp = Temperature.objects.all()
+    pressure = Pressure.objects.all()
+    humidity = Humidity.objects.all()
+    assert not temp.exists() and not pressure.exists() and not humidity.exists()
+
+
+def test_clean_db_dont_remove_values():
+    old_time = datetime.now() - timedelta(days=29)
+    mixer.blend('collector.Temperature', time=old_time)
+    mixer.blend('collector.Pressure', time=old_time)
+    mixer.blend('collector.Humidity', time=old_time)
+    collector.clean_db()
+    temp = Temperature.objects.all()
+    pressure = Pressure.objects.all()
+    humidity = Humidity.objects.all()
+    assert temp.exists() and pressure.exists() and humidity.exists()
+

sensors/run.sh

@@ -4,5 +4,6 @@ export DJANGO_SETTINGS_MODULE=sensors.settings.production
 while :
 do
     ./manage.py collect
+    ./manage.py clean
     sleep 600
 done