From 64b24171c46f4e2c64ed1e6c2ace54a1ccbdbb56 Mon Sep 17 00:00:00 2001
From: Petrik <petrik@deheus.net>
Date: Tue, 9 Jan 2024 20:54:27 +0100
Subject: [PATCH] Add code examples to `readonly` documentation

---
 activerecord/lib/active_record/core.rb  | 4 ++++
 guides/source/active_record_querying.md | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index 0d6d23e67f9..5393ed84fe6 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -697,6 +697,10 @@ module ActiveRecord
     end
 
     # Marks this record as read only.
+    #
+    #   customer = Customer.first
+    #   customer.readonly!
+    #   customer.save # Raises an ActiveRecord::ReadOnlyRecord
     def readonly!
       @readonly = true
     end
diff --git a/guides/source/active_record_querying.md b/guides/source/active_record_querying.md
index 3a1ddce891a..81779c41125 100644
--- a/guides/source/active_record_querying.md
+++ b/guides/source/active_record_querying.md
@@ -1305,7 +1305,7 @@ Active Record provides the [`readonly`][] method on a relation to explicitly dis
 ```ruby
 customer = Customer.readonly.first
 customer.visits += 1
-customer.save
+customer.save # Raises an ActiveRecord::ReadOnlyRecord
 ```
 
 As `customer` is explicitly set to be a readonly object, the above code will raise an `ActiveRecord::ReadOnlyRecord` exception when calling `customer.save` with an updated value of _visits_.