From 70ccaf6d5e4f348eae4992fcefc3b4f0673b7dc0 Mon Sep 17 00:00:00 2001
From: "Karl O. Pinc" <kop@karlpinc.com>
Date: Tue, 25 Feb 2025 15:19:44 -0600
Subject: [PATCH] Macro to prevent change of system maintained column

---
 db/include/macros.m4 | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/db/include/macros.m4 b/db/include/macros.m4
index 14fa0a5..47cd106 100644
--- a/db/include/macros.m4
+++ b/db/include/macros.m4
@@ -118,6 +118,28 @@ define({inserted_null}, {dnl
     END IF;
 })
 changequote(`,')
+dnl Plpgsql fragment for preventing values from being inserted into
+dnl columns which have automatically generated values.
+dnl This gets the user an error message instead of silently ignoring
+dnl the inserted value.
+dnl
+dnl Syntax: inserted_null(table, column)
+dnl Variables required:
+dnl Restrictions: Must be used in a FOR EACH ROW insert trigger function.
+changequote({,})
+define({inserted_null}, {dnl
+    IF NEW.$2 IS NOT NULL THEN
+      RAISE EXCEPTION data_exception USING
+            MESSAGE = 'Error updating $1'
+          , DETAIL = '($2) = ('
+                     || NEW.$2
+                     || '): $1.$2 must be NULL upon INSERT'
+          , HINT = 'This column contains automatically generated content;'
+                   ' insert NULL values or omit the column from the'
+                   ' INSERT statement';
+    END IF;
+})
+changequote(`,')
 
 dnl Strings used in error messages
 dnl
-- 
2.34.1