Add settings model generator (#13003)

* Add settings model generator

* Obey the CodeClimate overlords

* Update generator

* Update USAGE

* Add Zeitwerk exception

config/initializers/zeitwerk.rb

@@ -14,3 +14,4 @@ end
 Rails.autoloaders.main.ignore(Rails.root.join("lib/data_update_scripts"))
 Rails.autoloaders.main.ignore(Rails.root.join("lib/generators/data_update"))
 Rails.autoloaders.main.ignore(Rails.root.join("lib/generators/service"))
+Rails.autoloaders.main.ignore(Rails.root.join("lib/generators/settings_model"))

lib/generators/settings_model/USAGE

@@ -0,0 +1,42 @@
+Description:
+    Generates a settings model.
+
+Examples:
+    * Generating a settings model (you don't need to specify the Settings::
+      namespace)
+
+        $ rails generate settings_model Notification
+
+        # db/migrate/<timestamp>_create_settings_notifications.rb
+        class CreateSettingsNotifications < ActiveRecord::Migration[6.0]
+          def self.up
+            create_table :settings_notifications do |t|
+              t.string :var, null: false
+              t.text :value, null: true
+
+              t.timestamps
+            end
+
+            add_index :settings_notifications, :var, unique: true
+          end
+
+          def self.down
+            drop_table :settings_notifications
+          end
+        end
+
+        # app/models/settings/notification.rb
+        module Settings
+          class Notification < RailsSettings::Base
+            self.table_name = :settings_notifications
+
+            # The configuration is cached, change this if you want to force update
+            # the cache, or call Setting::Notification.clear_cache
+            cache_prefix { "v1" }
+
+            # Define your fields
+            # field :host, type: :string, default: "http://localhost:3000"
+            # field :default_locale, default: "en", type: :string
+          end
+        end
+

lib/generators/settings_model/settings_model_generator.rb

@@ -0,0 +1,59 @@
+# Based on https://github.com/huacnlee/rails-settings-cached/blob/main/lib/generators/settings/install_generator.rb
+
+require "rails/generators"
+require "rails/generators/migration"
+
+class SettingsModelGenerator < Rails::Generators::NamedBase
+  include Rails::Generators::Migration
+
+  argument :name, type: :string, default: "setting"
+
+  source_root File.expand_path("templates", __dir__)
+
+  @migrations = false
+
+  def self.next_migration_number(dirname) #:nodoc:
+    if ActiveRecord::Base.timestamped_migrations
+      if @migrations
+        (current_migration_number(dirname) + 1)
+      else
+        @migrations = true
+        Time.now.utc.strftime("%Y%m%d%H%M%S")
+      end
+    else
+      format "%.3<number>d", number: current_migration_number(dirname) + 1
+    end
+  end
+
+  def create_migration_file
+    migration_template(
+      "migration.erb",
+      "db/migrate/create_#{table_name}.rb",
+      migration_version: migration_version,
+      table_name: table_name,
+    )
+  end
+
+  def create_model
+    template(
+      "model.erb",
+      File.join("app/models/settings", class_path, "#{file_name}.rb"),
+    )
+  end
+
+  def rails_version_major
+    Rails::VERSION::MAJOR
+  end
+
+  def rails_version_minor
+    Rails::VERSION::MINOR
+  end
+
+  def migration_version
+    "[#{rails_version_major}.#{rails_version_minor}]" if rails_version_major >= 5
+  end
+
+  def table_name
+    @table_name ||= "settings_#{class_name.underscore.pluralize}"
+  end
+end

lib/generators/settings_model/templates/migration.erb

@@ -0,0 +1,16 @@
+class Create<%= table_name.camelize %> < ActiveRecord::Migration<%= migration_version %>
+  def self.up
+    create_table :<%= table_name %> do |t|
+      t.string :var, null: false
+      t.text :value, null: true
+
+      t.timestamps
+    end
+
+    add_index :<%= table_name %>, :var, unique: true
+  end
+
+  def self.down
+    drop_table :<%= table_name %>
+  end
+end

lib/generators/settings_model/templates/model.erb

@@ -0,0 +1,13 @@
+module Settings
+  class <%= class_name %> < RailsSettings::Base
+    self.table_name = :<%= table_name %>
+
+    # The configuration is cached, change this if you want to force update
+    # the cache, or call Settings::<%= class_name %>.clear_cache
+    cache_prefix { "v1" }
+
+    # Define your fields
+    # field :host, type: :string, default: "http://localhost:3000"
+    # field :default_locale, default: "en", type: :string
+  end
+end