Add +capitalize+ option to Inflector.humanize

So strings can be humanized without being capitalized:

    'employee_salary'.humanize                    # => "Employee salary"
    'employee_salary'.humanize(capitalize: false) # => "employee salary"

2 files changed, 26 insertions, 14 deletions

diff --git a/activesupport/lib/active_support/core_ext/string/inflections.rb b/activesupport/lib/active_support/core_ext/string/inflections.rb
index 56e8a5f98d..b7b750c77b 100644
--- a/activesupport/lib/active_support/core_ext/string/inflections.rb
+++ b/activesupport/lib/active_support/core_ext/string/inflections.rb
@@ -190,13 +190,19 @@ class String
     ActiveSupport::Inflector.classify(self)
   end
 
-  # Capitalizes the first word, turns underscores into spaces, and strips '_id'.
+  # Capitalizes the first word, turns underscores into spaces, and strips a
+  # trailing '_id' if present.
   # Like +titleize+, this is meant for creating pretty output.
   #
-  #   'employee_salary'.humanize # => "Employee salary"
-  #   'author_id'.humanize       # => "Author"
-  def humanize
-    ActiveSupport::Inflector.humanize(self)
+  # The capitalization of the first word can be turned off by setting the
+  # optional parameter +capitalize+ to false.
+  # By default, this parameter is true.
+  #
+  #   'employee_salary'.humanize              # => "Employee salary"
+  #   'author_id'.humanize                    # => "Author"
+  #   'author_id'.humanize(capitalize: false) # => "author"
+  def humanize(options = {})
+    ActiveSupport::Inflector.humanize(self, options)
   end
 
   # Creates a foreign key name from a class name.
diff --git a/activesupport/lib/active_support/inflector/methods.rb b/activesupport/lib/active_support/inflector/methods.rb
index ffdb7b53c4..0f7ae98a8a 100644
--- a/activesupport/lib/active_support/inflector/methods.rb
+++ b/activesupport/lib/active_support/inflector/methods.rb
@@ -98,20 +98,26 @@ module ActiveSupport
       word
     end
 
-    # Capitalizes the first word and turns underscores into spaces and strips a
-    # trailing "_id", if any. Like +titleize+, this is meant for creating pretty
-    # output.
-    #
-    #   'employee_salary'.humanize # => "Employee salary"
-    #   'author_id'.humanize       # => "Author"
-    def humanize(lower_case_and_underscored_word)
+    # Capitalizes the first word, turns underscores into spaces, and strips a
+    # trailing '_id' if present.
+    # Like +titleize+, this is meant for creating pretty output.
+    #
+    # The capitalization of the first word can be turned off by setting the
+    # optional parameter +capitalize+ to false.
+    # By default, this parameter is true.
+    #
+    #   humanize('employee_salary')              # => "Employee salary"
+    #   humanize('author_id')                    # => "Author"
+    #   humanize('author_id', capitalize: false) # => "author"
+    def humanize(lower_case_and_underscored_word, options = {})
       result = lower_case_and_underscored_word.to_s.dup
       inflections.humans.each { |(rule, replacement)| break if result.sub!(rule, replacement) }
       result.gsub!(/_id$/, "")
       result.tr!('_', ' ')
-      result.gsub(/([a-z\d]*)/i) { |match|
+      result.gsub!(/([a-z\d]*)/i) { |match|
         "#{inflections.acronyms[match] || match.downcase}"
-      }.gsub(/^\w/) { $&.upcase }
+      }
+      options.fetch(:capitalize, true) ? result.gsub(/^\w/) { $&.upcase } : result
     end
 
     # Capitalizes all the words and replaces some characters in the string to