1 files changed, 22 insertions, 16 deletions
diff --git a/activesupport/lib/active_support/core_ext/array/conversions.rb b/activesupport/lib/active_support/core_ext/array/conversions.rb
index 8718b7e1e5..1d4c83ae52 100644
--- a/activesupport/lib/active_support/core_ext/array/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/array/conversions.rb
@@ -1,8 +1,8 @@
-require 'active_support/xml_mini'
-require 'active_support/core_ext/hash/keys'
-require 'active_support/core_ext/string/inflections'
-require 'active_support/core_ext/object/to_param'
-require 'active_support/core_ext/object/to_query'
+require "active_support/xml_mini"
+require "active_support/core_ext/hash/keys"
+require "active_support/core_ext/string/inflections"
+require "active_support/core_ext/object/to_param"
+require "active_support/core_ext/object/to_query"
 
 class Array
   # Converts the array to a comma-separated sentence where the last element is
@@ -40,6 +40,12 @@ class Array
   #   ['one', 'two', 'three'].to_sentence(words_connector: ' or ', last_word_connector: ' or at least ')
   #   # => "one or two or at least three"
   #
+  #   [].to_sentence(fallback_string: 'none')
+  #   # => "none"
+  #
+  #   ['one', 'two'].to_sentence(fallback_string: 'none')
+  #   # => "one and two"
+  #
   # Using <tt>:locale</tt> option:
   #
   #   # Given this locale dictionary:
@@ -57,12 +63,12 @@ class Array
   #   ['uno', 'dos', 'tres'].to_sentence(locale: :es)
   #   # => "uno o dos o al menos tres"
   def to_sentence(options = {})
-    options.assert_valid_keys(:words_connector, :two_words_connector, :last_word_connector, :locale)
+    options.assert_valid_keys(:words_connector, :two_words_connector, :last_word_connector, :locale, :fallback_string)
 
     default_connectors = {
-      :words_connector     => ', ',
-      :two_words_connector => ' and ',
-      :last_word_connector => ', and '
+      words_connector: ", ",
+      two_words_connector: " and ",
+      last_word_connector: ", and "
     }
     if defined?(I18n)
       i18n_connectors = I18n.translate(:'support.array', locale: options[:locale], default: {})
@@ -72,7 +78,7 @@ class Array
 
     case length
     when 0
-      ''
+      "#{options[:fallback_string] || ''}"
     when 1
       "#{self[0]}"
     when 2
@@ -92,9 +98,9 @@ class Array
     case format
     when :db
       if empty?
-        'null'
+        "null"
       else
-        collect(&:id).join(',')
+        collect(&:id).join(",")
       end
     else
       to_default_s
@@ -179,7 +185,7 @@ class Array
   #   </messages>
   #
   def to_xml(options = {})
-    require 'active_support/builder' unless defined?(Builder)
+    require "active_support/builder" unless defined?(Builder)
 
     options = options.dup
     options[:indent]  ||= 2
@@ -187,9 +193,9 @@ class Array
     options[:root]    ||= \
       if first.class != Hash && all? { |e| e.is_a?(first.class) }
         underscored = ActiveSupport::Inflector.underscore(first.class.name)
-        ActiveSupport::Inflector.pluralize(underscored).tr('/', '_')
+        ActiveSupport::Inflector.pluralize(underscored).tr("/", "_")
       else
-        'objects'
+        "objects"
       end
 
     builder = options[:builder]
@@ -197,7 +203,7 @@ class Array
 
     root = ActiveSupport::XmlMini.rename_key(options[:root].to_s, options)
     children = options.delete(:children) || root.singularize
-    attributes = options[:skip_types] ? {} : { type: 'array' }
+    attributes = options[:skip_types] ? {} : { type: "array" }
 
     if empty?
       builder.tag!(root, attributes)