options_for_select_tag.rb

# options_for_select_tag: Create an options string for the Rails select_tag method.
# This is a wrapper for Rails' options_for_select method.
# The options are the same as the Rails select method, but this allows us to use it with the select_tag method.
#
# @param {String[]} container An array of strings representing the list of options.
# @param {String|String[]|Hash} selected_or_options A single value or an array of values that will be selected options in the final output, or a hash of options as follows:<br />
# - :selected - can be a single value or an array of values that will be selected options in the final output.
# - :include_blank - set to true or a prompt string if the first option element of the select element is a blank. Useful if there is not a default value required for the select element.<br />
# - :prompt - set to true or a prompt string. When the select element doesn‘t have a value yet, this prepends an option with a generic prompt — "Please select" — or the given prompt string.<br />
# - :disabled - can be a single value or an array of values that will be disabled options in the final output.
def options_for_select_tag(container, selected_or_options = nil)
  prompt = ''

  if selected_or_options.present?
    options = selected_or_options

    if options.class == Hash
      # Add the blank or prompt options if they are present
      if options[:include_blank].present? # :include_blank and :prompt are mutually exclusive
        if options[:include_blank].class == String
          prompt = "<option value=\"\">#{options[:include_blank]}</option>\n"
        else
          prompt = "<option value=\"\"></option>\n"
        end
      elsif options[:prompt].present? # :include_blank and :prompt are mutually exclusive
        if options[:prompt].class == String
          prompt = "<option value=\"\">#{options[:prompt]}</option>\n"
        else
          prompt = "<option value=\"\">Please select</option>\n"
        end
      end

      selected = {}

      if options[:selected].present?
        selected.merge!(:selected => options[:selected])
      end

      if options[:disabled].present?
        selected.merge!(:disabled => options[:disabled])
      end
    elsif options.class == String || options.class == Array
      selected = selected_or_options
    else # Error State
      raise ArgumentError, "'selected_or_options' parameter must be a String, Array of Strings, or a Hash of options.\n#{options.class} is invalid."
    end
  else # selected_or_options.blank?
    selected = nil
  end

  # Call Rails' options_for_select method with the proper arguments and prepent the prompt
  prompt + options_for_select(container, selected)
end

# options_from_csv: Create an options string for a select tag from a comma-separated file.
# This is a wrapper for Rails' options_for_select method.
# The options are the same as the Rails select method, but this allows us to use it with the select_tag method
#
# @param {String} csv A string containing comma-separated values.
# @param {String|String[]|Hash} selected_or_options A single value or an array of values that will be selected options in the final output, or a hash of options as follows:<br />
# - :split_on - the character to split the string on (default is ',').
# - :selected - can be a single value or an array of values that will be selected options in the final output.
# - :include_blank - set to true or a prompt string if the first option element of the select element is a blank. Useful if there is not a default value required for the select element.<br />
# - :prompt - set to true or a prompt string. When the select element doesn‘t have a value yet, this prepends an option with a generic prompt — "Please select" — or the given prompt string.<br />
# - :disabled - can be a single value or an array of values that will be disabled options in the final output.
def options_from_csv(csv, selected_or_options = nil)
  split_on = ','
  
  if selected_or_options.class == Hash && selected_or_options[:split_on].present?
    split_on = selected_or_options[:split_on]
  end
  container = csv.split(split_on).collect { |item| item.strip }

  options_for_select_tag(container, selected_or_options)
end

options_for_select_tag_spec.rb

describe "options_from_csv" do
  it "returns options" do
    helper.options_from_csv('US, Canada, UK').should == "<option value=\"US\">US</option>\n<option value=\"Canada\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options using an alternative separator" do
    helper.options_from_csv('US: Canada: UK', :split_on => ':').should == "<option value=\"US\">US</option>\n<option value=\"Canada\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with one selected" do
    helper.options_from_csv('US, Canada, UK', 'US').should == "<option value=\"US\" selected=\"selected\">US</option>\n<option value=\"Canada\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with one disabled" do
    helper.options_from_csv('US, Canada, UK', :disabled => 'US').should == "<option value=\"US\" disabled=\"disabled\">US</option>\n<option value=\"Canada\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with one selected and one disabled" do
    helper.options_from_csv('US, Canada, UK', :selected => 'Canada', :disabled => 'US').should == "<option value=\"US\" disabled=\"disabled\">US</option>\n<option value=\"Canada\" selected=\"selected\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with one selected and two disabled" do
    helper.options_from_csv('US, Canada, UK', :selected => 'Canada', :disabled => ['US', 'UK']).should == "<option value=\"US\" disabled=\"disabled\">US</option>\n<option value=\"Canada\" selected=\"selected\">Canada</option>\n<option value=\"UK\" disabled=\"disabled\">UK</option>"
  end

  it "returns options with two selected and one disabled" do
    helper.options_from_csv('US, Canada, UK', :disabled => 'Canada', :selected => ['US', 'UK']).should == "<option value=\"US\" selected=\"selected\">US</option>\n<option value=\"Canada\" disabled=\"disabled\">Canada</option>\n<option value=\"UK\" selected=\"selected\">UK</option>"
  end

  it "returns options with two disabled" do
    helper.options_from_csv('US, Canada, UK', :disabled => ['US', 'Canada']).should == "<option value=\"US\" disabled=\"disabled\">US</option>\n<option value=\"Canada\" disabled=\"disabled\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with two selected" do
    helper.options_from_csv('US, Canada, UK', ['US', 'Canada']).should == "<option value=\"US\" selected=\"selected\">US</option>\n<option value=\"Canada\" selected=\"selected\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with a blank included" do
    helper.options_from_csv('US, Canada, UK', :include_blank => true).should == "<option value=\"\"></option>\n<option value=\"US\">US</option>\n<option value=\"Canada\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with a prompt string (using include_blank)" do
    helper.options_from_csv('US, Canada, UK', :include_blank => 'None').should == "<option value=\"\">None</option>\n<option value=\"US\">US</option>\n<option value=\"Canada\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with a default prompt" do
    helper.options_from_csv('US, Canada, UK', :prompt => true).should == "<option value=\"\">Please select</option>\n<option value=\"US\">US</option>\n<option value=\"Canada\">Canada</option>\n<option value=\"UK\">UK</option>"
  end

  it "returns options with a prompt string (using prompt)" do
    helper.options_from_csv('US, Canada, UK', :prompt => 'Select Country').should == "<option value=\"\">Select Country</option>\n<option value=\"US\">US</option>\n<option value=\"Canada\">Canada</option>\n<option value=\"UK\">UK</option>"
  end
end

Lines #18-#41 in options_for_select_tag could be refactored to another method called something like "process_options_hash" for ease of reading.

Lines #19-24 and #25-31 look VERY similar. It might be worthwhile to refactor them into a simple function that takes a string and a default string like "set_prompt(str, default)." That might make the code a bit cleaner.

Lines #33-#41 could be refactored into a method called something like "set_selected(selected, disabled)."

Line #42 "options.class == String || options.class == Array" should be changed to a method called "default_selected_option(option)." That makes it clear that a String or Array is what the Rails method expects, and is passed through. We could also inverse the check with the hash check, since that is a quicker thing to resolve, and would make the code easier to read.

None of these changes should effect the the way the tests execute.