Default key attribute to id instead of looking up primary key

AGENTS.md

@@ -87,7 +87,7 @@ Allows data files to reference related records by instance name instead of forei
 
 ### Key Attribute Configuration
 
-By default, uses model's `primary_key`. Override for non-id keys:
+By default, uses model's `id` column. Override for non-id keys:
 
 ```ruby
 self.support_table_key_attribute = :name  # Use 'name' instead of 'id'

CHANGELOG.md

@@ -15,7 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Changed
 
 - The default data directory is now set in a Railtie and can be overridden with the `config.support_table.data_directory` option in the Rails application configuration.
-- The `support_table_key_attribute` method now returns the primary key of the model if not explicitly set instead of implicitly interpreting `nil` as the primary key. This makes the behavior more consistent and explicit.
+- The `support_table_key_attribute` method now returns "id" if not explicitly set instead of implicitly interpreting `nil` as the primary key. This makes the behavior more consistent and explicit and avoids edge cases when running the code in environments where the database connection is not available. This is a breaking change if the table uses a primary key other than "id" and the `support_table_key_attribute` was not explicitly set to that primary key.
 
 ## 1.4.0
 

lib/support_table_data.rb

@@ -41,8 +41,11 @@ def support_table_key_attribute=(attribute_name)
       self._support_table_key_attribute = attribute_name&.to_s
     end
 
+    # Get the attribute used as the unique to identify records in the data files.
+    #
+    # @return [String] The name of the key attribute.
     def support_table_key_attribute
-      _support_table_key_attribute || primary_key
+      _support_table_key_attribute || "id"
     end
 
     # Synchronize the rows in the table with the values defined in the data files added with

spec/models/group.rb

@@ -5,6 +5,7 @@ class Group < ActiveRecord::Base
 
   self.primary_key = :group_id
 
+  self.support_table_key_attribute = :group_id
   named_instance_attribute_helpers :group_id
 
   add_support_table_data "groups.yml"