Fix /api/tasks leads to 500 server error

cvat/apps/engine/models.py

@@ -12,13 +12,16 @@
 from django.conf import settings
 from django.contrib.auth.models import User
 from django.core.files.storage import FileSystemStorage
-from django.db import models
+from django.db import IntegrityError, models
 from django.db.models.fields import FloatField
 from drf_spectacular.types import OpenApiTypes
 from drf_spectacular.utils import extend_schema_field
+from rest_framework import exceptions
+
 from cvat.apps.engine.utils import parse_specific_attributes
 from cvat.apps.organizations.models import Organization
 
+
 class SafeCharField(models.CharField):
     def get_prep_value(self, value):
         value = super().get_prep_value(value)
@@ -502,10 +505,6 @@ def get_labels(self):
     class Meta:
         default_permissions = ()
 
-
-class InvalidLabel(ValueError):
-    pass
-
 class Label(models.Model):
     task = models.ForeignKey(Task, null=True, blank=True, on_delete=models.CASCADE)
     project = models.ForeignKey(Project, null=True, blank=True, on_delete=models.CASCADE)
@@ -520,6 +519,24 @@ def __str__(self):
     def has_parent_label(self):
         return bool(self.parent)
 
+    def save(self, force_insert=False, force_update=False, using=None,
+             update_fields=None):
+        try:
+            super().save(force_insert, force_update, using, update_fields)
+        except ValueError as exc:
+            raise exceptions.ValidationError(str(exc)) from exc
+        except IntegrityError:
+            raise exceptions.ValidationError("All label names must be unique")
+
+    @classmethod
+    def create(cls, **kwargs):
+        try:
+            return cls.objects.create(**kwargs)
+        except ValueError as exc:
+            raise exceptions.ValidationError(str(exc)) from exc
+        except IntegrityError:
+            raise exceptions.ValidationError("All label names must be unique")
+
     class Meta:
         default_permissions = ()
         constraints = [

cvat/apps/engine/serializers.py

@@ -15,7 +15,7 @@
 
 from rest_framework import serializers, exceptions
 from django.contrib.auth.models import User, Group
-from django.db import IntegrityError, transaction
+from django.db import transaction
 
 from cvat.apps.dataset_manager.formats.utils import get_label_color
 from cvat.apps.engine import models
@@ -287,15 +287,12 @@ def update_label(
 
             logger.info("Label id {} ({}) was updated".format(db_label.id, db_label.name))
         else:
-            try:
-                db_label = models.Label.objects.create(
-                    name=validated_data.get('name'),
-                    type=validated_data.get('type'),
-                    parent=parent_label,
-                    **parent_info
-                )
-            except IntegrityError as exc:
-                raise exceptions.ValidationError(str(exc)) from exc
+            db_label = models.Label.create(
+                name=validated_data.get('name'),
+                type=validated_data.get('type'),
+                parent=parent_label,
+                **parent_info
+            )
             logger.info("New {} label was created".format(db_label.name))
 
         if validated_data.get('deleted'):
@@ -312,10 +309,7 @@ def update_label(
         else:
             db_label.color = validated_data.get('color', db_label.color)
 
-        try:
-            db_label.save()
-        except models.InvalidLabel as exc:
-            raise exceptions.ValidationError(str(exc)) from exc
+        db_label.save()
 
         for attr in attributes:
             (db_attr, created) = models.AttributeSpec.objects.get_or_create(
@@ -361,10 +355,7 @@ def create_labels(cls,
 
             sublabels = label.pop('sublabels', [])
             svg = label.pop('svg', '')
-            try:
-                db_label = models.Label.objects.create(**label, **parent_info, parent=parent_label)
-            except IntegrityError as exc:
-                raise exceptions.ValidationError(str(exc)) from exc
+            db_label = models.Label.create(**label, **parent_info, parent=parent_label)
             logger.info(
                 f'label:create Label id:{db_label.id} for spec:{label} '
                 f'with sublabels:{sublabels}, parent_label:{parent_label}'