From bbc64e00b985895417e56483b5d48962c7c5514f Mon Sep 17 00:00:00 2001
From: "Karl O. Pinc" <kop@karlpinc.com>
Date: Tue, 30 Jan 2024 18:05:36 -0600
Subject: [PATCH] Add _error_immutable_view function to support un-updateable
 views

---
 db/schemas/lib/triggers/Makefile              |  3 +-
 .../triggers/create/_error_immutable_view.m4  | 54 +++++++++++++++++++
 .../triggers/drop/_error_immutable_view.m4    | 24 +++++++++
 3 files changed, 80 insertions(+), 1 deletion(-)
 create mode 100644 db/schemas/lib/triggers/create/_error_immutable_view.m4
 create mode 100644 db/schemas/lib/triggers/drop/_error_immutable_view.m4

diff --git a/db/schemas/lib/triggers/Makefile b/db/schemas/lib/triggers/Makefile
index 83c4e77..5ed227f 100644
--- a/db/schemas/lib/triggers/Makefile
+++ b/db/schemas/lib/triggers/Makefile
@@ -22,7 +22,8 @@
 ORDER := comm_ids \
          departtypes \
          biography_data \
-         comm_membs
+         comm_membs \
+         _error_immutable_view
 
 ##
 ## CAUTION: This Makefile is not designed to be run directly.  It is normally
diff --git a/db/schemas/lib/triggers/create/_error_immutable_view.m4 b/db/schemas/lib/triggers/create/_error_immutable_view.m4
new file mode 100644
index 0000000..8c42ef0
--- /dev/null
+++ b/db/schemas/lib/triggers/create/_error_immutable_view.m4
@@ -0,0 +1,54 @@
+dnl Copyright (C) 2012, 2024 The Meme Factory, Inc., http://www.karlpinc.com/
+dnl Copyright (C) 2007, 2008, Karl O. Pinc
+dnl
+dnl   This program is free software: you can redistribute it and/or modify
+dnl   it under the terms of the GNU Affero General Public License as published
+dnl   by the Free Software Foundation, either version 3 of the License, or
+dnl   (at your option) any later version.
+dnl
+dnl   This program is distributed in the hope that it will be useful,
+dnl   but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+dnl   GNU Affero General Public License for more details.
+dnl
+dnl   You should have received a copy of the GNU Affero General Public License
+dnl   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+dnl
+dnl Deliver an error message on an attempt to change a view.
+dnl Karl O. Pinc <kop@meme.com>
+dnl
+dnl
+dnl m4 includes
+include(`copyright.m4')dnl
+include(`constants.m4')dnl
+include(`macros.m4')dnl
+
+CREATE OR REPLACE FUNCTION
+  _error_immutable_view()
+  RETURNS TRIGGER
+  LANGUAGE plpgsql
+  sdb_function_set_search_path
+  AS $$
+  -- Deliver an error message on an attempt to change a view.
+  --
+  -- AGPL_notice(`  --', `2007, 2024', `Karl O. Pinc <kop@karlpinc.com>')
+  --
+  -- Syntax:  _error_immutable_view()
+  --
+  -- Input:
+  --
+  -- Returns:
+  --
+  -- Side Effects:
+  --   Raises an exception.
+  --
+  -- Remarks:
+  --   Used when somebody tries to modify a view.
+  BEGIN
+    RAISE EXCEPTION feature_not_supported USING
+          MESSAGE = TG_OP || ' not allowed on this view'
+        , DETAIL = 'The ' ||TG_RELNAME || ' view does not allow ' || TG_OP
+        , HINT = 'Perform the operation on the underlying table(s)';
+    RETURN NULL;
+  END;
+$$;
diff --git a/db/schemas/lib/triggers/drop/_error_immutable_view.m4 b/db/schemas/lib/triggers/drop/_error_immutable_view.m4
new file mode 100644
index 0000000..a5abfed
--- /dev/null
+++ b/db/schemas/lib/triggers/drop/_error_immutable_view.m4
@@ -0,0 +1,24 @@
+dnl Copyright (C) 2024 The Meme Factory, Inc.   http://www.karlpinc.com/
+dnl
+dnl   This program is free software: you can redistribute it and/or modify
+dnl   it under the terms of the GNU Affero General Public License as published by
+dnl   the Free Software Foundation, either version 3 of the License, or
+dnl   (at your option) any later version.
+dnl
+dnl   This program is distributed in the hope that it will be useful,
+dnl   but WITHOUT ANY WARRANTY; without even the implied warranty of
+dnl   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+dnl   GNU Affero General Public License for more details.
+dnl
+dnl   You should have received a copy of the GNU Affero General Public License
+dnl   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+dnl
+dnl Drop the function that says views can't "do stuff".  This drops all
+dnl triggers for views that use this function.
+dnl
+dnl Karl O. Pinc <kop@karlpinc.com>
+
+dnl m4 includes
+include(`copyright.m4')dnl
+
+DROP FUNCTION IF EXISTS _error_immutable_view() CASCADE;
-- 
2.34.1