Add custom validator and fix .html_safe with rescue

config/initializers/custom_validators.rb

@@ -0,0 +1,7 @@
+class AtLeastOneValidator < ActiveModel::EachValidator
+
+  def validate_each(record, attribute, value)
+    record.errors[attribute] << (options[:message] || I18n.t("errors.at_least_one")) if (value.blank? || value.values.join.eql?(''))
+  end
+
+end

config/locales/en.yml

@@ -79,6 +79,9 @@ en:
   visitors_this_month: This month's visitors
   visitors_this_year: This year's visitors
 
+  errors:
+    at_least_one: must at least have one value
+
   admin:
     access:
       denied:

config/locales/zh_tw.yml

@@ -77,6 +77,9 @@ zh_tw:
   visitors_this_month: 本月造訪
   visitors_this_year: 今年造訪
 
+  errors:
+    at_least_one: 必須至少有一個值
+    
   admin:
     access:
       denied: