Don't error when invalid json is assigned to a JSON column

Keeping with our behavior elsewhere in the system, invalid input is
assumed to be `nil`.

Fixes #18629.

1 files changed, 8 insertions, 0 deletions

diff --git a/activerecord/test/cases/adapters/postgresql/json_test.rb b/activerecord/test/cases/adapters/postgresql/json_test.rb
index 5f6cda1986..f5ae872483 100644
--- a/activerecord/test/cases/adapters/postgresql/json_test.rb
+++ b/activerecord/test/cases/adapters/postgresql/json_test.rb
@@ -179,6 +179,14 @@ module PostgresqlJSONSharedTestCases
     assert_equal({ 'one' => 'two', 'three' => 'four' }, json.payload)
     assert_not json.changed?
   end
+
+  def test_assigning_invalid_json
+    json = JsonDataType.new
+
+    json.payload = 'foo'
+
+    assert_nil json.payload
+  end
 end
 
 class PostgresqlJSONTest < ActiveRecord::TestCase