[sensors] Added unique together

feinstaub/sensors/migrations/0016_auto_20160209_2030.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9.2 on 2016-02-09 20:30
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('sensors', '0015_sensordata_software_version'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='sensordatavalue',
+            options={},
+        ),
+        migrations.AlterUniqueTogether(
+            name='sensordatavalue',
+            unique_together=set([('sensordata', 'value_type')]),
+        ),
+    ]

feinstaub/sensors/models.py

@@ -100,6 +100,9 @@ class SensorDataValue(TimeStampedModel):
     value_type = models.CharField(max_length=100, choices=SENSOR_TYPE_CHOICES,
                                   db_index=True)
 
+    class Meta:
+        unique_together = (('sensordata', 'value_type', ), )
+
     def __str__(self):
         return "{sensordata}: {value} [{value_type}]".format(
             sensordata=self.sensordata,