fix: deleting change requests with change sets throws 500 error (#4439)

api/features/workflows/core/models.py

@@ -263,14 +263,20 @@ def prevent_change_request_delete_if_committed(self) -> None:
 
     @property
     def live_from(self) -> datetime | None:
+        # Note: a change request can only have one of either
+        # feature_states, change_sets or environment_feature_versions
+
         # First we check if there are feature states associated with the change request
         # and, if so, we return the live_from of the feature state with the earliest
         # live_from.
         if first_feature_state := self.feature_states.order_by("live_from").first():
             return first_feature_state.live_from
 
-        # Then we do the same for environment feature versions. Note that a change request
-        # can not have feature states and environment feature versions.
+        # Then we check the change sets.
+        elif first_change_set := self.change_sets.order_by("live_from").first():
+            return first_change_set.live_from
+
+        # Finally, we do the same for environment feature versions.
         elif first_environment_feature_version := self.environment_feature_versions.order_by(
             "live_from"
         ).first():

api/tests/unit/features/workflows/core/test_unit_workflows_models.py

@@ -1,5 +1,7 @@
+import json
 from datetime import timedelta
 
+import freezegun
 import pytest
 from django.contrib.sites.models import Site
 from django.utils import timezone
@@ -16,7 +18,10 @@
 from audit.related_object_type import RelatedObjectType
 from environments.models import Environment
 from features.models import Feature, FeatureState
-from features.versioning.models import EnvironmentFeatureVersion
+from features.versioning.models import (
+    EnvironmentFeatureVersion,
+    VersionChangeSet,
+)
 from features.versioning.versioning_service import get_environment_flags_list
 from features.workflows.core.exceptions import (
     CannotApproveOwnChangeRequest,
@@ -731,3 +736,40 @@ def test_committing_change_request_with_environment_feature_versions_creates_pub
         related_object_type=RelatedObjectType.EF_VERSION.name,
         log=ENVIRONMENT_FEATURE_VERSION_PUBLISHED_MESSAGE % feature.name,
     ).exists()
+
+
+def test_change_request_live_from_for_change_request_with_change_set(
+    feature: Feature,
+    environment_v2_versioning: Environment,
+    admin_user: FFAdminUser,
+) -> None:
+    # Given
+    change_request = ChangeRequest.objects.create(
+        title="Test CR",
+        environment=environment_v2_versioning,
+        user=admin_user,
+    )
+    VersionChangeSet.objects.create(
+        change_request=change_request,
+        feature=feature,
+        feature_states_to_update=json.dumps(
+            [
+                {
+                    "feature_segment": None,
+                    "enabled": True,
+                    "feature_state_value": {
+                        "type": "unicode",
+                        "string_value": "updated",
+                    },
+                }
+            ]
+        ),
+    )
+
+    # When
+    now = timezone.now()
+    with freezegun.freeze_time(now):
+        change_request.commit(admin_user)
+
+    # Then
+    assert change_request.live_from == now