Fetch a role by its ID.

1 files changed, 22 insertions, 2 deletions

diff --git a/gn_auth/auth/authorisation/roles/models.py b/gn_auth/auth/authorisation/roles/models.py
index 94ad2d1..699e3b3 100644
--- a/gn_auth/auth/authorisation/roles/models.py
+++ b/gn_auth/auth/authorisation/roles/models.py
@@ -2,8 +2,7 @@
 from uuid import UUID, uuid4
 from functools import reduce
 from dataclasses import dataclass
-
-from typing import Sequence, Iterable
+from typing import Sequence, Iterable, Optional
 
 from pymonad.either import Left, Right, Either
 
@@ -219,3 +218,24 @@ def assign_user_role_by_name(
                 "role_id": role["role_id"],
                 "resource_id": str(resource_id)
             })
+
+
+def role_by_id(conn: db.DbConnection, role_id: UUID) -> Optional[Role]:
+    """Fetch a role from the database by its ID."""
+    with db.cursor(conn) as cursor:
+        cursor.execute(
+            "SELECT r.*, p.* FROM roles AS r INNER JOIN role_privileges AS rp "
+            "ON r.role_id=rp.role_id INNER JOIN privileges AS p "
+            "ON rp.privilege_id=p.privilege_id "
+            "WHERE r.role_id=?",
+            (str(role_id),))
+        results = cursor.fetchall()
+
+    if not bool(results):
+        return None
+
+    _roles = db_rows_to_roles(results)
+    if len(_roles) > 1:
+        raise Exception("Data corruption: Expected a single role.")
+
+    return _roles[0]