implements new option :month_format_string for date select helpers [Closes #13618]

3 files changed, 48 insertions, 9 deletions

diff --git a/actionview/CHANGELOG.md b/actionview/CHANGELOG.md
index 30dbc20f18..a0f298a6b1 100644
--- a/actionview/CHANGELOG.md
+++ b/actionview/CHANGELOG.md
@@ -1,3 +1,17 @@
+*   Date select helpers accept a format string for the months selector via the
+    new option `:month_format_string`.
+
+    When rendered, the format string gets passed keys `:number` (integer), and
+    `:name` (string), in order to be able to interpolate them as in
+
+        '%{name} (%<number>02d)'
+
+    for example.
+
+    This option is motivated by #13618.
+
+    *Xavier Noria*
+
 *   Added `config.action_view.raise_on_missing_translations` to define whether an
     error should be raised for missing translations.
 
diff --git a/actionview/lib/action_view/helpers/date_helper.rb b/actionview/lib/action_view/helpers/date_helper.rb
index 3d091c4a00..698f0ca31c 100644
--- a/actionview/lib/action_view/helpers/date_helper.rb
+++ b/actionview/lib/action_view/helpers/date_helper.rb
@@ -169,6 +169,9 @@ module ActionView
       #   "2 - February" instead of "February").
       # * <tt>:use_month_names</tt>   - Set to an array with 12 month names if you want to customize month names.
       #   Note: You can also use Rails' i18n functionality for this.
+      # * <tt>:month_format_string</tt> - Set to a format string. The string gets passed keys +:number+ (integer)
+      #   and +:name+ (string). A format string would be something like "%{name} (%<number>02d)" for example.
+      #   See <tt>Kernel.sprintf</tt> for documentation on format sequences.
       # * <tt>:date_separator</tt>    - Specifies a string to separate the date fields. Default is "" (i.e. nothing).
       # * <tt>:start_year</tt>        - Set the start year for the year select. Default is <tt>Date.today.year - 5</tt>if
       #   you are creating new record. While editing existing record, <tt>:start_year</tt> defaults to
@@ -850,24 +853,36 @@ module ActionView
           I18n.translate(key, :locale => @options[:locale])
         end
 
-        # Lookup month name for number.
-        #  month_name(1) => "January"
+        # Looks up month names by number (1-based):
         #
-        # If <tt>:use_month_numbers</tt> option is passed
-        #  month_name(1) => 1
+        #   month_name(1) # => "January"
         #
-        # If <tt>:use_two_month_numbers</tt> option is passed
-        #  month_name(1) => '01'
+        # If the <tt>:use_month_numbers</tt> option is passed:
         #
-        # If <tt>:add_month_numbers</tt> option is passed
-        #  month_name(1) => "1 - January"
+        #   month_name(1) # => 1
+        #
+        # If the <tt>:use_two_month_numbers</tt> option is passed:
+        #
+        #   month_name(1) # => '01'
+        #
+        # If the <tt>:add_month_numbers</tt> option is passed:
+        #
+        #   month_name(1) # => "1 - January"
+        #
+        # If the <tt>:month_format_string</tt> option is passed:
+        #
+        #   month_name(1) # => "January (01)"
+        #
+        # depending on the format string.
         def month_name(number)
           if @options[:use_month_numbers]
             number
           elsif @options[:use_two_digit_numbers]
-            sprintf "%02d", number
+            '%02d' % number
           elsif @options[:add_month_numbers]
             "#{number} - #{month_names[number]}"
+          elsif format_string = @options[:month_format_string]
+            format_string % {number: number, name: month_names[number]}
           else
             month_names[number]
           end
diff --git a/actionview/test/template/date_helper_test.rb b/actionview/test/template/date_helper_test.rb
index 5f09aef249..6f77c3c99d 100644
--- a/actionview/test/template/date_helper_test.rb
+++ b/actionview/test/template/date_helper_test.rb
@@ -326,6 +326,16 @@ class DateHelperTest < ActionView::TestCase
     assert_dom_equal expected, select_month(8, :add_month_numbers => true)
   end
 
+  def test_select_month_with_format_string
+    expected = %(<select id="date_month" name="date[month]">\n)
+    expected << %(<option value="1">January (01)</option>\n<option value="2">February (02)</option>\n<option value="3">March (03)</option>\n<option value="4">April (04)</option>\n<option value="5">May (05)</option>\n<option value="6">June (06)</option>\n<option value="7">July (07)</option>\n<option value="8" selected="selected">August (08)</option>\n<option value="9">September (09)</option>\n<option value="10">October (10)</option>\n<option value="11">November (11)</option>\n<option value="12">December (12)</option>\n)
+    expected << "</select>\n"
+
+    format_string = '%{name} (%<number>02d)'
+    assert_dom_equal expected, select_month(Time.mktime(2003, 8, 16), :month_format_string => format_string)
+    assert_dom_equal expected, select_month(8, :month_format_string => format_string)
+  end
+
   def test_select_month_with_numbers_and_names_with_abbv
     expected = %(<select id="date_month" name="date[month]">\n)
     expected << %(<option value="1">1 - Jan</option>\n<option value="2">2 - Feb</option>\n<option value="3">3 - Mar</option>\n<option value="4">4 - Apr</option>\n<option value="5">5 - May</option>\n<option value="6">6 - Jun</option>\n<option value="7">7 - Jul</option>\n<option value="8" selected="selected">8 - Aug</option>\n<option value="9">9 - Sep</option>\n<option value="10">10 - Oct</option>\n<option value="11">11 - Nov</option>\n<option value="12">12 - Dec</option>\n)