Allow deleting a UserGroup (except for the default one)

fractal_server/app/routes/auth/group.py

@@ -4,6 +4,7 @@
 from fastapi import APIRouter
 from fastapi import Depends
 from fastapi import HTTPException
+from fastapi import Response
 from fastapi import status
 from sqlalchemy.exc import IntegrityError
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -12,14 +13,16 @@
 from sqlmodel import select
 
 from . import current_active_superuser
-from ...db import get_async_db
-from ...schemas.user_group import UserGroupCreate
-from ...schemas.user_group import UserGroupRead
-from ...schemas.user_group import UserGroupUpdate
 from ._aux_auth import _get_single_group_with_user_ids
+from fractal_server.app.db import get_async_db
 from fractal_server.app.models import LinkUserGroup
 from fractal_server.app.models import UserGroup
 from fractal_server.app.models import UserOAuth
+from fractal_server.app.models.v2 import TaskGroupV2
+from fractal_server.app.schemas.user_group import UserGroupCreate
+from fractal_server.app.schemas.user_group import UserGroupRead
+from fractal_server.app.schemas.user_group import UserGroupUpdate
+from fractal_server.app.security import FRACTAL_DEFAULT_GROUP_NAME
 from fractal_server.logger import set_logger
 
 logger = set_logger(__name__)
@@ -174,18 +177,49 @@ async def update_single_group(
     return updated_group
 
 
-@router_group.delete(
-    "/group/{group_id}/", status_code=status.HTTP_405_METHOD_NOT_ALLOWED
-)
+@router_group.delete("/group/{group_id}/", status_code=204)
 async def delete_single_group(
     group_id: int,
     user: UserOAuth = Depends(current_active_superuser),
     db: AsyncSession = Depends(get_async_db),
-) -> UserGroupRead:
-    raise HTTPException(
-        status_code=status.HTTP_405_METHOD_NOT_ALLOWED,
-        detail=(
-            "Deleting a user group is not allowed, as it may restrict "
-            "previously-granted access.",
-        ),
+) -> Response:
+
+    group = await db.get(UserGroup, group_id)
+
+    # Preliminary checks
+
+    if group is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail=f"UserGroup {group_id} not found.",
+        )
+    if group.name == FRACTAL_DEFAULT_GROUP_NAME:
+        raise HTTPException(
+            status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+            detail=(
+                "Cannot delete default UserGroup "
+                f"'{FRACTAL_DEFAULT_GROUP_NAME}'."
+            ),
+        )
+
+    # Cascade operations
+
+    res = await db.execute(
+        select(LinkUserGroup).where(LinkUserGroup.group_id == group_id)
     )
+    for link in res.scalars().all():
+        await db.delete(link)
+
+    res = await db.execute(
+        select(TaskGroupV2).where(TaskGroupV2.user_group_id == group_id)
+    )
+    for task_group in res.scalars().all():
+        task_group.user_group_id = None
+        db.add(task_group)
+
+    # Delete
+
+    await db.delete(group)
+    await db.commit()
+
+    return Response(status_code=status.HTTP_204_NO_CONTENT)

tests/no_version/test_api_user_groups.py

@@ -93,7 +93,9 @@ async def test_update_group(registered_superuser_client):
     assert res.json()["viewer_paths"] == ["/new"]
 
 
-async def test_user_group_crud(registered_superuser_client):
+async def test_user_group_crud(
+    registered_superuser_client, db, default_user_group
+):
     """
     Test basic working of POST/GET/PATCH for user groups.
     """
@@ -127,7 +129,7 @@ async def test_user_group_crud(registered_superuser_client):
     assert res.status_code == 201
     group_2_id = res.json()["id"]
 
-    # Add user A to group 1
+    # Add user A and B to group 1
     res = await registered_superuser_client.patch(
         f"{PREFIX}/group/{group_1_id}/",
         json=dict(new_user_ids=[user_A_id, user_B_id]),
@@ -145,20 +147,22 @@ async def test_user_group_crud(registered_superuser_client):
     )
     assert res.status_code == 200
     groups_data = res.json()
-    assert len(groups_data) == 2
+    assert len(groups_data) == 3
     for group in groups_data:
         if group["name"] == "group 1":
             assert set(group["user_ids"]) == {user_A_id, user_B_id}
         elif group["name"] == "group 2":
             assert group["user_ids"] == [user_B_id]
+        elif group["name"] == default_user_group.name:
+            assert set(group["user_ids"]) == {user_A_id, user_B_id}
         else:
             raise RuntimeError("Wrong branch.")
 
     # Get all groups (group 1, group 2) without user_ids
     res = await registered_superuser_client.get(f"{PREFIX}/group/")
     assert res.status_code == 200
     groups_data = res.json()
-    assert len(groups_data) == 2
+    assert len(groups_data) == 3
     for group in groups_data:
         assert group["user_ids"] is None
 
@@ -187,6 +191,44 @@ async def test_user_group_crud(registered_superuser_client):
     assert res.status_code == 422
     assert "`new_user_ids` list has repetitions'" in str(res.json())
 
+    # DELETE (and cascade operations)
+    from sqlmodel import select
+    from fractal_server.app.models import LinkUserGroup
+    from fractal_server.app.models.v2 import TaskGroupV2
+
+    task_group = TaskGroupV2(
+        user_id=user_A_id,
+        user_group_id=group_1_id,
+        origin="pypi",
+        pkg_name="fractal-tasks-core",
+    )
+    db.add(task_group)
+    await db.commit()
+    await db.refresh(task_group)
+    assert task_group.user_group_id == group_1_id
+
+    res = await registered_superuser_client.delete(  # actual DELETE
+        f"{PREFIX}/group/{group_1_id}/"
+    )
+    assert res.status_code == 204
+    res = await registered_superuser_client.delete(
+        f"{PREFIX}/group/{group_1_id}/"
+    )
+    assert res.status_code == 404
+    res = await registered_superuser_client.delete(
+        f"{PREFIX}/group/{default_user_group.id}/"
+    )
+    assert res.status_code == 422
+
+    # test cascade operations
+    res = await db.execute(
+        select(LinkUserGroup).where(LinkUserGroup.group_id == group_1_id)
+    )
+    links = res.scalars().all()
+    assert links == []
+    await db.refresh(task_group)
+    assert task_group.user_group_id is None
+
 
 async def test_create_user_group_same_name(registered_superuser_client):
     """