fix: use correct constraint on Observations (#15235)

Author: miketheman

warehouse/migrations/versions/812e14a4cddf_cascade_observation_delete.py

@@ -0,0 +1,81 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+cascade observation delete
+
+Revision ID: 812e14a4cddf
+Revises: a073e7979805
+Create Date: 2024-01-18 18:46:58.482270
+"""
+
+from alembic import op
+
+revision = "812e14a4cddf"
+down_revision = "9a0ed2044b53"
+
+
+def upgrade():
+    op.drop_constraint(
+        "project_observations_related_id_fkey",
+        "project_observations",
+        type_="foreignkey",
+    )
+    op.create_foreign_key(
+        None,
+        "project_observations",
+        "projects",
+        ["related_id"],
+        ["id"],
+        onupdate="CASCADE",
+        ondelete="CASCADE",
+    )
+    op.drop_constraint(
+        "release_observations_related_id_fkey",
+        "release_observations",
+        type_="foreignkey",
+    )
+    op.create_foreign_key(
+        None,
+        "release_observations",
+        "releases",
+        ["related_id"],
+        ["id"],
+        onupdate="CASCADE",
+        ondelete="CASCADE",
+    )
+
+
+def downgrade():
+    op.drop_constraint(
+        "release_observations_related_id_fkey",
+        "release_observations",
+        type_="foreignkey",
+    )
+    op.create_foreign_key(
+        "release_observations_related_id_fkey",
+        "release_observations",
+        "releases",
+        ["related_id"],
+        ["id"],
+    )
+    op.drop_constraint(
+        "project_observations_related_id_fkey",
+        "project_observations",
+        type_="foreignkey",
+    )
+    op.create_foreign_key(
+        "project_observations_related_id_fkey",
+        "project_observations",
+        "projects",
+        ["related_id"],
+        ["id"],
+    )

warehouse/observations/models.py

@@ -184,7 +184,11 @@ def observations(cls):  # noqa: N805
                 },
                 related_id=mapped_column(
                     PG_UUID,
-                    ForeignKey(f"{cls.__tablename__}.id"),
+                    ForeignKey(
+                        f"{cls.__tablename__}.id",
+                        onupdate="CASCADE",
+                        ondelete="CASCADE",
+                    ),
                     comment="The ID of the related model",
                     nullable=False,
                     index=True,
@@ -199,7 +203,7 @@ def observations(cls):  # noqa: N805
                 observer=relationship(Observer),
             ),
         )
-        return relationship(cls.Observation)
+        return relationship(cls.Observation, cascade="all, delete-orphan")
 
     def record_observation(
         self,