Fix reloading with custom classes (#22)

CHANGELOG.md

@@ -3,6 +3,8 @@
 - Drop support for _Ruby_ < 3.1 (EOL)
 - Added search functionality
 - Added registry to store relationships between _Customizable_ types and _Active Field_ types
+- Added notes about the necessity of disabling reloading for custom model classes and custom _Active Field_ type models
+to prevent _STI_ (_Single Table Inheritance_) issues
 
 **Breaking changes**:
 - Maximum datetime precision reduced to 6 for all _Ruby_/_Rails_ versions.

README.md

@@ -4,7 +4,7 @@
 [![Gem downloads count](https://img.shields.io/gem/dt/active_fields)](https://rubygems.org/gems/active_fields)
 [![Github Actions CI](https://github.com/lassoid/active_fields/actions/workflows/main.yml/badge.svg?branch=main)](https://github.com/lassoid/active_fields/actions/workflows/main.yml)
 
-**ActiveFields** is a _Rails_ plugin that implements the _Entity-Attribute-Value (EAV)_ pattern,
+**ActiveFields** is a _Rails_ plugin that implements the _Entity-Attribute-Value_ (_EAV_) pattern,
 enabling the addition of custom fields to any model at runtime without requiring changes to the database schema.
 
 ## Key Concepts
@@ -596,6 +596,25 @@ class CustomValue < ApplicationRecord
 end
 ```
 
+**Note:** To avoid _STI_ (_Single Table Inheritance_) issues in environments with code reloading (`config.enable_reloading = true`),
+you should ensure that your custom model classes, along with all their superclasses and mix-ins, are non-reloadable.
+Follow these steps:
+- Move your custom model classes to a separate folder, such as `app/models/active_fields`.
+- If your custom model classes subclass `ApplicationRecord` (or other reloadable class) or mix-in reloadable modules,
+move those superclasses and modules to another folder, such as `app/models/core`.
+- After organizing your files, add the following code to your `config/application.rb`:
+    ```ruby
+    # Disable custom models reloading to avoid STI issues.
+    custom_models_dir = "#{root}/app/models/active_fields"
+    models_core_dir = "#{root}/app/models/core"
+    Rails.autoloaders.main.ignore(custom_models_dir, models_core_dir)
+    Rails.autoloaders.once.collapse(custom_models_dir, models_core_dir)
+    config.autoload_once_paths += [custom_models_dir, models_core_dir]
+    config.eager_load_paths += [custom_models_dir, models_core_dir]
+    ```
+    This configuration disables namespaces for these folders
+    and adds them to `autoload_once_paths`, ensuring they are not reloaded.
+
 ### Adding Custom Field Types
 
 To add a custom _Active Field_ type, create a subclass of the `ActiveFields.config.field_base_class`,
@@ -682,6 +701,9 @@ class IpArrayField < ActiveFields.config.field_base_class
 end
 ```
 
+**Note:** Similar to custom model classes, you should disable code reloading for custom _Active Field_ type models.
+Place them in the `app/models/active_fields` folder too.
+
 For each custom _Active Field_ type, you must define a **validator**, a **caster** and optionally a **finder**:
 
 #### Validator

app/models/active_fields/field.rb

@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+module ActiveFields
+  module Field; end
+end

lib/active_fields/engine.rb

@@ -8,7 +8,8 @@ class Engine < ::Rails::Engine
 
     # Disable models reloading to avoid STI issues.
     # Reloading can prevent subclasses from recognizing the base class.
-    config.autoload_once_paths = %W[#{root}/app/models #{root}/app/models/concerns]
+    config.autoload_once_paths << "#{root}/app/models"
+    config.autoload_once_paths << "#{root}/app/models/concerns"
 
     initializer "active_fields.active_record" do
       ActiveSupport.on_load(:active_record) do

spec/dummy/app/models/custom_field.rb → spec/dummy/app/models/active_fields/custom_field.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-# If the field base class is set to default, we disallow loading the custom class.
+# If the field base class is set to default, we disallow loading the custom model class.
 # This is an inversion of the same conditional statement from ActiveFields::Field::Base
 if ActiveFields.config.field_base_class_changed?
   class CustomField < ApplicationRecord

spec/dummy/app/models/custom_value.rb → spec/dummy/app/models/active_fields/custom_value.rb

@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-# If the value class is set to default, we disallow loading the custom class.
+# If the value class is set to default, we disallow loading the custom model class.
 # This is an inversion of the same conditional statement from ActiveFields::Value
 if ActiveFields.config.value_class_changed?
   class CustomValue < ApplicationRecord

spec/dummy/config/application.rb

@@ -32,6 +32,16 @@ class Application < Rails::Application
     # Common ones are `templates`, `generators`, or `middleware`, for example.
     config.autoload_lib(ignore: %w(assets tasks))
 
+    # Disable custom models reloading to avoid STI issues.
+    # Since custom models are subclasses of ApplicationRecord, it should also not be reloadable.
+    # Move it to `app/models/core`.
+    custom_models_dir = "#{root}/app/models/active_fields"
+    models_core_dir = "#{root}/app/models/core"
+    Rails.autoloaders.main.ignore(custom_models_dir, models_core_dir)
+    Rails.autoloaders.once.collapse(custom_models_dir, models_core_dir)
+    config.autoload_once_paths += [custom_models_dir, models_core_dir]
+    config.eager_load_paths += [custom_models_dir, models_core_dir]
+
     # Force UTC time zone
     config.time_zone = "UTC"
     config.active_record.default_timezone = :utc