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require 'active_support/dependencies'
module ActionController
# The Rails framework provides a large number of helpers for working with +assets+, +dates+, +forms+,
# +numbers+ and model objects, to name a few. These helpers are available to all templates
# by default.
#
# In addition to using the standard template helpers provided in the Rails framework, creating custom helpers to
# extract complicated logic or reusable functionality is strongly encouraged. By default, the controller will
# include a helper whose name matches that of the controller, e.g., <tt>MyController</tt> will automatically
# include <tt>MyHelper</tt>.
#
# Additional helpers can be specified using the +helper+ class method in <tt>ActionController::Base</tt> or any
# controller which inherits from it.
#
# ==== Examples
# The +to_s+ method from the Time class can be wrapped in a helper method to display a custom message if
# the Time object is blank:
#
# module FormattedTimeHelper
# def format_time(time, format=:long, blank_message=" ")
# time.blank? ? blank_message : time.to_s(format)
# end
# end
#
# FormattedTimeHelper can now be included in a controller, using the +helper+ class method:
#
# class EventsController < ActionController::Base
# helper FormattedTimeHelper
# def index
# @events = Event.find(:all)
# end
# end
#
# Then, in any view rendered by <tt>EventController</tt>, the <tt>format_time</tt> method can be called:
#
# <% @events.each do |event| -%>
# <p>
# <% format_time(event.time, :short, "N/A") %> | <%= event.name %>
# </p>
# <% end -%>
#
# Finally, assuming we have two event instances, one which has a time and one which does not,
# the output might look like this:
#
# 23 Aug 11:30 | Carolina Railhawks Soccer Match
# N/A | Carolina Railhaws Training Workshop
#
module Helpers
extend ActiveSupport::Concern
include AbstractController::Helpers
included do
# Set the default directory for helpers
extlib_inheritable_accessor(:helpers_dir) do
defined?(RAILS_ROOT) ? "#{RAILS_ROOT}/app/helpers" : "app/helpers"
end
end
module ClassMethods
def inherited(klass)
klass.class_eval { default_helper_module! unless name.blank? }
super
end
# The +helper+ class method can take a series of helper module names, a block, or both.
#
# ==== Parameters
# *args<Array[Module, Symbol, String, :all]>
# block<Block>:: A block defining helper methods
#
# ==== Examples
# When the argument is a string or symbol, the method will provide the "_helper" suffix, require the file
# and include the module in the template class. The second form illustrates how to include custom helpers
# when working with namespaced controllers, or other cases where the file containing the helper definition is not
# in one of Rails' standard load paths:
# helper :foo # => requires 'foo_helper' and includes FooHelper
# helper 'resources/foo' # => requires 'resources/foo_helper' and includes Resources::FooHelper
#
# When the argument is a module it will be included directly in the template class.
# helper FooHelper # => includes FooHelper
#
# When the argument is the symbol <tt>:all</tt>, the controller will include all helpers beneath
# <tt>ActionController::Base.helpers_dir</tt> (defaults to <tt>app/helpers/**/*.rb</tt> under RAILS_ROOT).
# helper :all
#
# Additionally, the +helper+ class method can receive and evaluate a block, making the methods defined available
# to the template.
# # One line
# helper { def hello() "Hello, world!" end }
# # Multi-line
# helper do
# def foo(bar)
# "#{bar} is the very best"
# end
# end
#
# Finally, all the above styles can be mixed together, and the +helper+ method can be invoked with a mix of
# +symbols+, +strings+, +modules+ and blocks.
# helper(:three, BlindHelper) { def mice() 'mice' end }
#
def helper(*args, &block)
super(*_modules_for_helpers(args), &block)
end
# Declares helper accessors for controller attributes. For example, the
# following adds new +name+ and <tt>name=</tt> instance methods to a
# controller and makes them available to the view:
# helper_attr :name
# attr_accessor :name
#
# ==== Parameters
# *attrs<Array[String, Symbol]>:: Names of attributes to be converted
# into helpers.
def helper_attr(*attrs)
attrs.flatten.each { |attr| helper_method(attr, "#{attr}=") }
end
# Provides a proxy to access helpers methods from outside the view.
def helpers
@helper_proxy ||= ActionView::Base.new.extend(_helpers)
end
private
# Returns a list of modules, normalized from the acceptable kinds of
# helpers with the following behavior:
# String or Symbol:: :FooBar or "FooBar" becomes "foo_bar_helper",
# and "foo_bar_helper.rb" is loaded using require_dependency.
# :all:: Loads all modules in the #helpers_dir
# Module:: No further processing
#
# After loading the appropriate files, the corresponding modules
# are returned.
#
# ==== Parameters
# args<Array[String, Symbol, Module, all]>:: A list of helpers
#
# ==== Returns
# Array[Module]:: A normalized list of modules for the list of
# helpers provided.
def _modules_for_helpers(args)
args.flatten.map! do |arg|
case arg
when :all
_modules_for_helpers all_application_helpers
when String, Symbol
file_name = "#{arg.to_s.underscore}_helper"
require_dependency(file_name, "Missing helper file helpers/%s.rb")
file_name.camelize.constantize
when Module
arg
else
raise ArgumentError, "helper must be a String, Symbol, or Module"
end
end
end
def default_helper_module!
module_name = name.sub(/Controller$/, '')
module_path = module_name.underscore
helper module_path
rescue MissingSourceFile => e
raise e unless e.is_missing? "#{module_path}_helper"
rescue NameError => e
raise e unless e.missing_name? "#{module_name}Helper"
end
# Extract helper names from files in app/helpers/**/*.rb
def all_application_helpers
extract = /^#{Regexp.quote(helpers_dir)}\/?(.*)_helper.rb$/
Dir["#{helpers_dir}/**/*_helper.rb"].map { |file| file.sub extract, '\1' }
end
end
end
end
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