diff --git a/competition/models.py b/competition/models.py
index f3bbab87..e4984d43 100644
--- a/competition/models.py
+++ b/competition/models.py
@@ -150,7 +150,7 @@ class Meta:
     start = models.DateTimeField(verbose_name='dátum začiatku súťaže')
     end = models.DateTimeField(verbose_name='dátum konca súťaže')
     additional_name = models.CharField(
-        max_length=50, verbose_name='Prísvlastok súťaže', null=True, blank=True)
+        max_length=50, verbose_name='Prívlastok súťaže', null=True, blank=True)
 
     objects = ActiveQuerySet.as_manager()
 
@@ -204,6 +204,11 @@ class Meta:
         blank=True,
         default=None)
 
+    def save(self, *args, **kwargs) -> None:
+        if not self.frozen_results:
+            self.frozen_results = None
+        return super().save(*args, **kwargs)
+
     def get_first_series(self):
         return self.series_set.get(order=1)
 
@@ -251,6 +256,11 @@ class Meta:
         blank=True,
         default=None)
 
+    def save(self, *args, **kwargs) -> None:
+        if not self.frozen_results:
+            self.frozen_results = None
+        return super().save(*args, **kwargs)
+
     def __str__(self):
         return f'{self.semester} - {self.order}. séria'
 
@@ -415,6 +425,11 @@ class Meta:
     hidden_response = models.TextField(
         null=True, blank=True, verbose_name='Skrytá odpoveď na komentár')
 
+    def save(self, *args, **kwargs) -> None:
+        if not self.hidden_response:
+            self.hidden_response = None
+        return super().save(*args, **kwargs)
+
     def publish(self):
         self.state = CommentPublishState.PUBLISHED
         self.hidden_response = None
diff --git a/competition/serializers.py b/competition/serializers.py
index 70151eb7..9f37b0bc 100644
--- a/competition/serializers.py
+++ b/competition/serializers.py
@@ -60,7 +60,7 @@ class Meta:
 
 @ts_interface(context='competition')
 class CompetitionSerializer(serializers.ModelSerializer):
-    competition_type = CompetitionTypeSerializer(many=False)
+    competition_type = CompetitionTypeSerializer(many=False, read_only=True)
     upcoming_or_current_event = serializers.SerializerMethodField(
         'get_upcoming_or_current')
     history_events = serializers.SerializerMethodField('get_history_events')
diff --git a/competition/tests.py b/competition/tests.py
index 023281ff..4df28c50 100644
--- a/competition/tests.py
+++ b/competition/tests.py
@@ -316,11 +316,11 @@ def test_get_competition_list(self):
 
     def test_get_competition_detail(self):
         '''detail format OK'''
-        response = self.client.get(self.URL_PREFIX + '/strom', {}, 'json')
+        response = self.client.get(self.URL_PREFIX + '/slug/strom', {}, 'json')
         self.assertEqual(response.status_code, 200)
         self.competition_assert_format(response.json(), 0)
 
-        response = self.client.get(self.URL_PREFIX + '/matik', {}, 'json')
+        response = self.client.get(self.URL_PREFIX + '/slug/matik', {}, 'json')
         self.assertEqual(response.status_code, 200)
         self.competition_assert_format(response.json(), 1)
 
@@ -331,13 +331,25 @@ def test_permission_list(self):
 
     def test_permission_get(self):
         '''retrieve permission OK'''
-        self.check_permissions(self.URL_PREFIX + '/strom/',
+        self.check_permissions(self.URL_PREFIX + '/slug/strom/',
                                'GET', self.PUBLIC_OK_RESPONSES)
 
     def test_permission_update(self):
         ''' update permission OK'''
-        self.check_permissions(self.URL_PREFIX + '/strom/', 'PUT',
-                               self.ALL_FORBIDDEN, {'start_year': 2020})
+        self.check_permissions(self.URL_PREFIX + '/0/', 'PUT',
+                               self.ONLY_STROM_OK_RESPONSES,
+                               {
+                                   "id": 0,
+                                   "name": "STROM",
+                                   "slug": "strom",
+                                   "start_year": 1976,
+                                   "description": "popis",
+                                   "rules": "# Pravidlá",
+                                   "min_years_until_graduation": 0,
+                                   "sites": [
+                                       0
+                                   ]
+                               })
 
     def test_permission_create(self):
         ''' create permission OK'''
diff --git a/competition/views.py b/competition/views.py
index c45d0d9f..fd88360f 100644
--- a/competition/views.py
+++ b/competition/views.py
@@ -12,6 +12,7 @@
 from rest_framework.decorators import action
 from rest_framework.exceptions import ValidationError
 from rest_framework.permissions import IsAdminUser, IsAuthenticated
+from rest_framework.request import Request
 from rest_framework.response import Response
 
 from base.utils import mime_type
@@ -100,13 +101,22 @@ def generate_result_row(
     }
 
 
-class CompetitionViewSet(viewsets.ReadOnlyModelViewSet):
+class CompetitionViewSet(mixins.RetrieveModelMixin,
+                         mixins.UpdateModelMixin,
+                         mixins.ListModelMixin,
+                         viewsets.GenericViewSet):
     """Naše aktivity"""
     queryset = Competition.objects.all()
     serializer_class = CompetitionSerializer
-    lookup_field = 'slug'
     permission_classes = (CompetitionRestrictedPermission,)
 
+    @action(detail=False, url_path=r'slug/(?P<slug>\w+)')
+    def slug(self, request: Request, slug: str = None) -> Response:
+        competition: Competition = self.get_queryset().get(slug=slug)
+        return Response(
+            CompetitionSerializer(competition, many=False).data
+        )
+
 
 class CommentViewSet(
     mixins.RetrieveModelMixin,
diff --git a/personal/views.py b/personal/views.py
index cf030313..61dc107c 100644
--- a/personal/views.py
+++ b/personal/views.py
@@ -1,5 +1,5 @@
 from django_filters.rest_framework import DjangoFilterBackend
-from rest_framework import status, viewsets
+from rest_framework import exceptions, status, viewsets
 from rest_framework.decorators import action
 from rest_framework.filters import SearchFilter
 from rest_framework.permissions import IsAdminUser, IsAuthenticated
@@ -26,7 +26,7 @@ class DistrictViewSet(viewsets.ReadOnlyModelViewSet):
     filterset_fields = ['county', ]
 
 
-class SchoolViewSet(viewsets.ReadOnlyModelViewSet):
+class SchoolViewSet(viewsets.ModelViewSet):
     """Školy"""
     queryset = School.objects.all()
     serializer_class = SchoolSerializer
@@ -34,6 +34,15 @@ class SchoolViewSet(viewsets.ReadOnlyModelViewSet):
     filter_backends = [DjangoFilterBackend, SearchFilter]
     search_fields = ['name', 'street']
 
+    def destroy(self, request, *args, **kwargs):
+        """Zmazanie školy"""
+        instance = self.get_object()
+        if Profile.objects.filter(school=instance).exists():
+            raise exceptions.ValidationError(
+                detail='Nie je možné zmazať školu, ktorá má priradených užívateľov.')
+        self.perform_destroy(instance)
+        return Response(status=status.HTTP_204_NO_CONTENT)
+
 
 class ProfileViewSet(viewsets.ModelViewSet):
     """Užívateľské profily"""