feat: allow user deletion without deleting task references

src/backend/app/db/models.py

@@ -221,6 +221,41 @@ async def all(
             )
             return await cur.fetchall()
 
+    @classmethod
+    async def delete(cls, db: Connection, user_id: int) -> bool:
+        """Delete a user and their related data."""
+        async with db.cursor() as cur:
+            await cur.execute(
+                """
+                UPDATE task_events SET user_id = NULL WHERE user_id = %(user_id)s;
+            """,
+                {"user_id": user_id},
+            )
+            await cur.execute(
+                """
+                UPDATE projects SET author_id = NULL WHERE author_id = %(user_id)s;
+            """,
+                {"user_id": user_id},
+            )
+            await cur.execute(
+                """
+                DELETE FROM organisation_managers WHERE user_id = %(user_id)s;
+            """,
+                {"user_id": user_id},
+            )
+            await cur.execute(
+                """
+                DELETE FROM user_roles WHERE user_id = %(user_id)s;
+            """,
+                {"user_id": user_id},
+            )
+            await cur.execute(
+                """
+                DELETE FROM users WHERE id = %(user_id)s;
+            """,
+                {"user_id": user_id},
+            )
+
     @classmethod
     async def create(
         cls,
@@ -605,11 +640,11 @@ class DbTaskEvent(BaseModel):
 
     project_id: Annotated[Optional[int], Field(gt=0)] = None
     user_id: Annotated[Optional[int], Field(gt=0)] = None
+    username: Optional[str] = None
     comment: Optional[str] = None
     created_at: Optional[AwareDatetime] = None
 
     # Computed
-    username: Optional[str] = None
     profile_img: Optional[str] = None
     # Computed via database trigger
     state: Optional[MappingState] = None
@@ -662,13 +697,12 @@ async def all(
 
         sql = f"""
             SELECT
-                *,
-                u.username,
+                the.*,
                 u.profile_img
             FROM
-                public.task_events
-            JOIN
-                users u ON u.id = task_events.user_id
+                public.task_events the
+            LEFT JOIN
+                users u ON u.id = the.user_id
             WHERE {filters_joined}
             ORDER BY created_at DESC;
         """
@@ -696,18 +730,19 @@ async def create(
                         INSERT INTO public.task_events (
                             event_id,
                             project_id,
+                            username,
                             {columns}
                         )
                         VALUES (
                             gen_random_uuid(),
                             (SELECT project_id FROM tasks WHERE id = %(task_id)s),
+                            (SELECT username FROM users WHERE id = %(user_id)s),
                             {value_placeholders}
                         )
                         RETURNING *
                     )
                     SELECT
                         inserted.*,
-                        u.username,
                         u.profile_img
                     FROM inserted
                     JOIN users u ON u.id = inserted.user_id;

src/backend/app/users/user_routes.py

@@ -19,11 +19,13 @@
 
 from typing import Annotated, List
 
-from fastapi import APIRouter, Depends
+from fastapi import APIRouter, Depends, Response
+from loguru import logger as log
 from psycopg import Connection
 
 from app.auth.roles import mapper, super_admin
 from app.db.database import db_conn
+from app.db.enums import HTTPStatus
 from app.db.enums import UserRole as UserRoleEnum
 from app.db.models import DbUser
 from app.users import user_schemas
@@ -66,3 +68,18 @@ async def get_user_roles(current_user: Annotated[DbUser, Depends(mapper)]):
     for role in UserRoleEnum:
         user_roles[role.name] = role.value
     return user_roles
+
+
+@router.delete("/{id}")
+async def delete_user_by_identifier(
+    user: Annotated[DbUser, Depends(get_user)],
+    current_user: Annotated[DbUser, Depends(super_admin)],
+    db: Annotated[Connection, Depends(db_conn)],
+):
+    """Delete a single user."""
+    log.info(
+        f"User {current_user.username} attempting deletion of user {user.username}"
+    )
+    await DbUser.delete(db, user.id)
+    log.info(f"User {user.id} deleted successfully.")
+    return Response(status_code=HTTPStatus.NO_CONTENT)

src/backend/migrations/010-delete-user.sql

@@ -0,0 +1,47 @@
+-- ## Migration to:
+-- * Enable user data deletion
+
+-- Start a transaction
+BEGIN;
+
+-- Add column 'username' to 'task_events' table
+DO $$
+BEGIN
+    IF NOT EXISTS (
+        SELECT 1
+        FROM information_schema.columns
+        WHERE table_name='task_events' AND column_name='username'
+    ) THEN
+        ALTER TABLE public.task_events
+        ADD COLUMN username VARCHAR;
+    END IF;
+END $$;
+
+-- Make 'user_id' nullable in 'task_events' table
+DO $$
+BEGIN
+    IF EXISTS (
+        SELECT 1
+        FROM information_schema.columns
+        WHERE table_name='task_events' AND column_name='user_id' AND is_nullable = 'NO'
+    ) THEN
+        ALTER TABLE public.task_events
+        ALTER COLUMN user_id DROP NOT NULL;
+    END IF;
+END $$;
+
+-- Make 'author_id' nullable in 'projects' table
+DO $$
+BEGIN
+    IF EXISTS (
+        SELECT 1
+        FROM information_schema.columns
+        WHERE table_name='projects' AND column_name='author_id' AND is_nullable = 'NO'
+    ) THEN
+        ALTER TABLE public.projects
+        ALTER COLUMN author_id DROP NOT NULL;
+    END IF;
+END $$;
+
+-- Commit the transaction
+COMMIT;