Allow only one location per friend

map/migrations/0004_auto_20190302_1455.py

@@ -0,0 +1,20 @@
+# Generated by Django 2.1.7 on 2019-03-02 14:55
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('map', '0003_friendlocation_friend'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='friendlocation',
+            name='friend',
+            field=models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, to=settings.AUTH_USER_MODEL),
+        ),
+    ]

map/migrations/0005_auto_20190302_1457.py

@@ -0,0 +1,20 @@
+# Generated by Django 2.1.7 on 2019-03-02 14:57
+
+from django.conf import settings
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('map', '0004_auto_20190302_1455'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='friendlocation',
+            name='friend',
+            field=models.OneToOneField(on_delete=django.db.models.deletion.CASCADE, related_name='location', to=settings.AUTH_USER_MODEL),
+        ),
+    ]

map/models.py

@@ -26,7 +26,7 @@ class FriendLocation(BaseModel):
     longitude = CoordinateField()
     start_date = models.DateField('from', blank=True, null=True)
     end_date = models.DateField('until', blank=True, null=True)
-    friend = models.ForeignKey(Friend, on_delete=models.CASCADE)
+    friend = models.OneToOneField(Friend, on_delete=models.CASCADE, related_name='location')
 
     @property
     def latitude_str(self):