README.md in rails-settings-cached-2.4.1 vs README.md in rails-settings-cached-2.5.0

@@ -28,13 +28,13 @@
 You will get `app/models/setting.rb`
 
 ```rb
 class Setting < RailsSettings::Base
   # cache_prefix { "v1" }
-  field :app_name, default: "Rails Settings"
+  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"
+  field :default_locale, default: "zh-CN", validates: { presence: true, inclusion: { in: %w[zh-CN en jp] } }
   field :readonly_item, type: :integer, default: 100, readonly: true
   field :user_limits, type: :integer, default: 20
   field :exchange_rate, type: :float, default: 0.123
   field :admin_emails, type: :array, default: %w[[e-mail]]
   field :captcha_enable, type: :boolean, default: true
@@ -47,11 +47,11 @@
     logging: true,
     sender_email: "[e-mail]"
   }
 
   # lambda default value
-  field :welcome_message, type: :string, default: -> { "welcome to #{self.app_name}" }
+  field :welcome_message, type: :string, default: -> { "welcome to #{self.app_name}" }, validates: { length: { maximum: 255 } }
 end
 ```
 
 You must use the `field` method to statement the setting keys, otherwise you can't use it.
 
@@ -148,10 +148,43 @@
 => { key: "host", type: :string, default: "http://example.com", readonly: true }
 Setting.get_field("app_name")
 => { key: "app_name", type: :string, default: "Rails Settings", readonly: false }
 ```
 
+## Validations
+
+You can use `validates` options to special the [Rails Validation](https://api.rubyonrails.org/classes/ActiveModel/Validations/ClassMethods.html#method-i-validates) for fields.
+
+```rb
+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.
+
+```rb
+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`
@@ -263,13 +296,29 @@
 
 ```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
@@ -282,9 +331,19 @@
 
 app/views/admin/settings/show.html.erb
 
 ```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>