Rails Settings Cached

The best solution for store global settings in Rails applications.

This gem will make managing a table of а global key, value pairs easy. Think of it like a global Hash stored in your database, that uses simple ActiveRecord like methods for manipulation. Keep track of any global setting that you don't want to hard code into your Rails application.

Installation

Edit your Gemfile:

$ bundle add rails-settings-cached

Generate your settings:

$ rails g settings:install

# Or use a custom name:
$ rails g settings:install AppConfig

You will get app/models/setting.rb

class Setting < RailsSettings::Base
  # cache_prefix { "v1" }

  scope :application do
    field :app_name, default: "Rails Settings", validates: { presence: true, length: { in: 2..20 } }
    field :host, default: "http://example.com", readonly: true
    field :default_locale, default: "zh-CN", validates: { presence: true, inclusion: { in: %w[zh-CN en jp] } }, option_values: %w[en zh-CN jp], help_text: "Bla bla ..."
    field :admin_emails, type: :array, default: %w[admin@rubyonrails.org]

    # lambda default value
    field :welcome_message, type: :string, default: -> { "welcome to #{self.app_name}" }, validates: { length: { maximum: 255 } }
    # Override array separator, default: /[\n,]/ split with \n or comma.
    field :tips, type: :array, separator: /[\n]+/
  end

  scope :limits do
    field :user_limits, type: :integer, default: 20
    field :exchange_rate, type: :float, default: 0.123
    field :captcha_enable, type: :boolean, default: true
  end

  field :notification_options, type: :hash, default: {
    send_all: true,
    logging: true,
    sender_email: "foo@bar.com"
  }

  field :readonly_item, type: :integer, default: 100, readonly: true
end

You must use the field method to statement the setting keys, otherwise you can't use it.

The scope method allows you to group the keys for admin UI.

Now just put that migration in the database with:

$ rails db:migrate

Usage

The syntax is easy. First, let's create some settings to keep track of:

irb > Setting.host
"http://example.com"
irb > Setting.app_name
"Rails Settings"
irb > Setting.app_name = "Rails Settings Cached"
irb > Setting.app_name
"Rails Settings Cached"

irb > Setting.user_limits
20
irb > Setting.user_limits = "30"
irb > Setting.user_limits
30
irb > Setting.user_limits = 45
irb > Setting.user_limits
45

irb > Setting.captcha_enable
1
irb > Setting.captcha_enable?
true
irb > Setting.captcha_enable = "0"
irb > Setting.captcha_enable
false
irb > Setting.captcha_enable = "1"
irb > Setting.captcha_enable
true
irb > Setting.captcha_enable = "false"
irb > Setting.captcha_enable
false
irb > Setting.captcha_enable = "true"
irb > Setting.captcha_enable
true
irb > Setting.captcha_enable?
true

irb > Setting.admin_emails
["admin@rubyonrails.org"]
irb > Setting.admin_emails = %w[foo@bar.com bar@dar.com]
irb > Setting.admin_emails
["foo@bar.com", "bar@dar.com"]
irb > Setting.admin_emails = "huacnlee@gmail.com,admin@admin.com\nadmin@rubyonrails.org"
irb > Setting.admin_emails
["huacnlee@gmail.com", "admin@admin.com", "admin@rubyonrails.org"]

irb > Setting.notification_options
{
  send_all: true,
  logging: true,
  sender_email: "foo@bar.com"
}
irb > Setting.notification_options = {
  sender_email: "notice@rubyonrails.org"
}
irb > Setting.notification_options
{
  sender_email: "notice@rubyonrails.org"
}

Get defined fields

version 2.3+

# Get all keys
Setting.keys
=> ["app_name", "host", "default_locale", "readonly_item"]

# Get editable keys
Setting.editable_keys
=> ["app_name", "default_locale"]

# Get readonly keys
Setting.readonly_keys
=> ["host", "readonly_item"]

# Get field
Setting.get_field("host")
=> { scope: :application, key: "host", type: :string, default: "http://example.com", readonly: true }
Setting.get_field("app_name")
=> { scope: :application, key: "app_name", type: :string, default: "Rails Settings", readonly: false }
Setting.get_field(:user_limits)
=> { scope: :limits, key: "user_limits", type: :integer, default: 20, readonly: false }
# Get field options
Setting.get_field("default_locale")[:options]
=> { option_values: %w[en zh-CN jp], help_text: "Bla bla ..." }

Custom type for setting

Since: 2.9.0

You can write your custom field type by under RailsSettings::Fields module.

For example

module RailsSettings
  module Fields
    class YesNo < ::RailsSettings::Fields::Base
      def serialize(value)
        case value
        when true then "YES"
        when false then "NO"
        else raise StandardError, 'invalid value'
        end
      end

      def deserialize(value)
        case value
        when "YES" then true
        when "NO" then false
        else nil
        end
      end
    end
  end
end

Now you can use yes_no type in you setting:

class Setting
  field :custom_item, type: :yes_no, default: 'YES'
end

irb> Setting.custom_item = 'YES'
irb> Setting.custom_item
true
irb> Setting.custom_item = 'NO'
irb> Setting.custom_item
false

Get All defined fields

version 2.7.0+

You can use defined_fields method to get all defined fields in Setting.

# Get editable fields and group by scope
editable_fields = Setting.defined_fields
  .select { |field| !field[:readonly] }
  .group_by { |field| field[:scope] }

Validations

You can use validates options to special the Rails Validation for fields.

class Setting < RailsSettings::Base
  # cache_prefix { "v1" }
  field :app_name, default: "Rails Settings", validates: { presence: true, length: { in: 2..20 } }
  field :default_locale, default: "zh-CN", validates: { presence: true, inclusion: { in: %w[zh-CN en jp], message: "is not included in [zh-CN, en, jp]" } }
end

Now validate will work on record save:

irb> Setting.app_name = ""
ActiveRecord::RecordInvalid: (Validation failed: App name can't be blank)
irb> Setting.app_name = "Rails Settings"
"Rails Settings"
irb> Setting.default_locale = "zh-TW"
ActiveRecord::RecordInvalid: (Validation failed: Default locale is not included in [zh-CN, en, jp])
irb> Setting.default_locale = "en"
"en"

Validate by save / valid? method:

setting = Setting.find_or_initialize_by(var: :app_name)
setting.value = ""
setting.valid?
# => false
setting.errors.full_messages
# => ["App name can't be blank", "App name too short (minimum is 2 characters)"]

setting = Setting.find_or_initialize_by(var: :default_locale)
setting.value = "zh-TW"
setting.save
# => false
setting.errors.full_messages
# => ["Default locale is not included in [zh-CN, en, jp]"]
setting.value = "en"
setting.valid?
# => true

Use Setting in Rails initializing:

In version 2.3+ you can use Setting before Rails is initialized.

For example config/initializers/devise.rb

Devise.setup do |config|
  if Setting.omniauth_google_client_id.present?
    config.omniauth :google_oauth2, Setting.omniauth_google_client_id, Setting.omniauth_google_client_secret
  end
end

class Setting < RailsSettings::Base
  field :omniauth_google_client_id, default: ENV["OMNIAUTH_GOOGLE_CLIENT_ID"]
  field :omniauth_google_client_secret, default: ENV["OMNIAUTH_GOOGLE_CLIENT_SECRET"]
end

Readonly field

You may also want use Setting before Rails initialize:

config/environments/*.rb

If you want do that do that, the setting field must has readonly: true.

For example:

class Setting < RailsSettings::Base
  field :mailer_provider, default: (ENV["mailer_provider"] || "smtp"), readonly: true
  field :mailer_options, type: :hash, readonly: true, default: {
    address: ENV["mailer_options.address"],
    port: ENV["mailer_options.port"],
    domain: ENV["mailer_options.domain"],
    user_name: ENV["mailer_options.user_name"],
    password: ENV["mailer_options.password"],
    authentication: ENV["mailer_options.authentication"] || "login",
    enable_starttls_auto: ENV["mailer_options.enable_starttls_auto"]
  }
end

config/environments/production.rb

# You must require_relative directly in Rails 6.1+ in config/environments/production.rb
require_relative "../../app/models/setting"

Rails.application.configure do
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = Setting.mailer_options.deep_symbolize_keys
end

TIP: You also can follow this file to rewrite ActionMailer's mail method for configuration Mail options from Setting after Rails booted.

https://github.com/ruby-china/homeland/blob/main/app/mailers/application_mailer.rb#L19

Caching flow:

Setting.host -> Check Cache -> Exist - Get value of key for cache -> Return
                   |
                Fetch all key and values from DB -> Write Cache -> Get value of key for cache -> return
                   |
                Return default value or nil

In each Setting keys call, we will load the cache/db and save in ActiveSupport::CurrentAttributes to avoid hit cache/db.

Each key update will expire the cache, so do not add some frequent update key.

Change cache key

Some times you may need to force update cache, now you can use cache_prefix

class Setting < RailsSettings::Base
  cache_prefix { "you-prefix" }
  ...
end

In testing, you need add Setting.clear_cache for each Test case:

class ActiveSupport::TestCase
  teardown do
    Setting.clear_cache
  end
end

How to manage Settings in the admin interface?

If you want to create an admin interface to editing the Settings, you can try methods in following:

config/routes.rb

namespace :admin do
  resource :settings
end

app/controllers/admin/settings_controller.rb

module Admin
  class SettingsController < ApplicationController
    def create
      @errors = ActiveModel::Errors.new
      setting_params.keys.each do |key|
        next if setting_params[key].nil?

        setting = Setting.new(var: key)
        setting.value = setting_params[key].strip
        unless setting.valid?
          @errors.merge!(setting.errors)
        end
      end

      if @errors.any?
        render :new
      end

      setting_params.keys.each do |key|
        Setting.send("#{key}=", setting_params[key].strip) unless setting_params[key].nil?
      end

      redirect_to admin_settings_path, notice: "Setting was successfully updated."
    end

    private
      def setting_params
        params.require(:setting).permit(:host, :user_limits, :admin_emails,
          :captcha_enable, :notification_options)
      end
  end
end

app/views/admin/settings/show.html.erb

<%= form_for(Setting.new, url: admin_settings_path) do |f| %>
  <% if @errors.any? %>
    <div class="alert alert-block alert-danger">
      <ul>
        <% @errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
        <% end %>
      </ul>
    </div>
  <% end %>

  <div class="form-group">
    <label class="control-label">Host</label>
    <%= f.text_field :host, value: Setting.host, class: "form-control", placeholder: "http://localhost"  %>
  </div>

  <div class="form-group form-checkbox">
    <label>
      <%= f.check_box :captcha_enable, checked: Setting.captcha_enable? %>
      Enable/Disable Captcha
    </label>
  </div>

  <div class="form-group">
    <label class="control-label">Admin Emails</label>
    <%= f.text_area :admin_emails, value: Setting.admin_emails.join("\n"), class: "form-control" %>
  </div>

  <div class="form-group">
    <label class="control-label">Notification options</label>
    <%= f.text_area :notification_options, value: YAML.dump(Setting.notification_options), class: "form-control", style: "height: 180px;"  %>
    <div class="form-text">
      Use YAML format to config the SMTP_html
    </div>
  </div>

  <div>
    <%= f.submit 'Update Settings' %>
  </div>
<% end %>

Special Cache Storage

You can use cache_store to change cache storage, default is Rails.cache.

Add config/initializers/rails_settings.rb

RailsSettings.configure do
  self.cache_storage = ActiveSupport::Cache::RedisCacheStore.new(url: "redis://localhost:6379")
end

Scoped Settings

🚨 BREAK CHANGES WARNING: rails-settings-cached 2.x has redesigned the API, the new version will compatible with the stored setting values by an older version. When you want to upgrade 2.x, you must read the README again, and follow guides to change your Setting model. 0.x stable branch: https://github.com/huacnlee/rails-settings-cached/tree/0.x

Backward compatible to support 0.x scoped settings

For new project / new user of rails-settings-cached. The ActiveRecord::AttributeMethods::Serialization is best choice.

This is reason of why rails-settings-cached 2.x removed Scoped Settings feature.

For example:

We wants a preferences setting for user.

class User < ActiveRecord::Base
  serialize :preferences
end

@user = User.new
@user.preferences[:receive_emails] = true
@user.preferences[:public_email] = true
@user.save

Use cases:

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