maps: order map layers alphabetically (#16907)

combo/apps/maps/migrations/0001_initial.py

@@ -21,5 +21,6 @@ class Migration(migrations.Migration):
                 ('icon', models.CharField(blank=True, max_length=32, null=True, verbose_name='Marker icon', choices=[(b'house', 'House'), (b'building', 'Building'), (b'hospital', 'Hospital'), (b'ambulance', 'Ambulance'), (b'taxi', 'Taxi'), (b'subway', 'Subway'), (b'wheelchair', 'Wheelchair'), (b'bicycle', 'Bicycle'), (b'car', 'Car'), (b'train', 'Train'), (b'bus', 'Bus'), (b'motorcycle', 'Motorcycle'), (b'truck', 'Truck')])),
                 ('icon_colour', models.CharField(default=b'#FFFFFF', max_length=7, verbose_name='Icon colour')),
             ],
+            options={'ordering': ('label',)}
         ),
     ]

combo/apps/maps/models.py

@@ -64,6 +64,9 @@ class MapLayer(models.Model):
             _('Include user identifier in request'),
             default=True)
 
+    class Meta:
+        ordering = ('label',)
+
     def save(self, *args, **kwargs):
         if not self.slug:
             base_slug = slugify(self.label)