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module ActionController #:nodoc:
module Helpers #:nodoc:
HELPERS_DIR = (defined?(RAILS_ROOT) ? "#{RAILS_ROOT}/app/helpers" : "app/helpers")
def self.included(base)
# Initialize the base module to aggregate its helpers.
base.class_inheritable_accessor :master_helper_module
base.master_helper_module = Module.new
# Extend base with class methods to declare helpers.
base.extend(ClassMethods)
base.class_eval do
# Wrap inherited to create a new master helper module for subclasses.
class << self
alias_method_chain :inherited, :helper
end
end
end
# The Rails framework provides a large number of helpers for working with +assets+, +dates+, +forms+,
# +numbers+ and +ActiveRecord+ 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 ClassMethods
# Makes all the (instance) methods in the helper module available to templates rendered through this controller.
# See ActionView::Helpers (link:classes/ActionView/Helpers.html) for more about making your own helper modules
# available to the templates.
def add_template_helper(helper_module) #:nodoc:
master_helper_module.send(:include, helper_module)
end
# The +helper+ class method can take a series of helper module names, a block, or both.
#
# * <tt>*args</tt>: One or more +Modules+, +Strings+ or +Symbols+, or the special symbol <tt>:all</tt>.
# * <tt>&block</tt>: 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 includes all helpers from
# <tt>app/views/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)
args.flatten.each do |arg|
case arg
when Module
add_template_helper(arg)
when :all
helper(all_application_helpers)
when String, Symbol
file_name = arg.to_s.underscore + '_helper'
class_name = file_name.camelize
begin
require_dependency(file_name)
rescue LoadError => load_error
requiree = / -- (.*?)(\.rb)?$/.match(load_error).to_a[1]
if requiree == file_name
msg = "Missing helper file helpers/#{file_name}.rb"
raise LoadError.new(msg).copy_blame!(load_error)
else
raise
end
end
add_template_helper(class_name.constantize)
else
raise ArgumentError, "helper expects String, Symbol, or Module argument (was: #{args.inspect})"
end
end
# Evaluate block in template class if given.
master_helper_module.module_eval(&block) if block_given?
end
# Declare a controller method as a helper. For example, the following
# makes the +current_user+ controller method available to the view:
# class ApplicationController < ActionController::Base
# helper_method :current_user
# def current_user
# @current_user ||= User.find(session[:user])
# end
# end
def helper_method(*methods)
methods.flatten.each do |method|
master_helper_module.module_eval <<-end_eval
def #{method}(*args, &block)
controller.send(%(#{method}), *args, &block)
end
end_eval
end
end
# Declares helper accessors for controller attributes. For example, the
# following adds new +name+ and <tt>name=</tt> instance methods to a
# controller and makes them available to the view:
# helper_attr :name
# attr_accessor :name
def helper_attr(*attrs)
attrs.flatten.each { |attr| helper_method(attr, "#{attr}=") }
end
private
def default_helper_module!
module_name = name.sub(/Controller$|$/, 'Helper')
module_path = module_name.split('::').map { |m| m.underscore }.join('/')
require_dependency module_path
helper module_name.constantize
rescue MissingSourceFile => e
raise unless e.is_missing? module_path
logger.debug("#{name}: missing default helper path #{module_path}") if logger
rescue NameError => e
raise unless e.missing_name? module_name
logger.debug("#{name}: missing default helper module #{module_name}") if logger
end
def inherited_with_helper(child)
inherited_without_helper(child)
begin
child.master_helper_module = Module.new
child.master_helper_module.send :include, master_helper_module
child.send :default_helper_module!
rescue MissingSourceFile => e
raise unless e.is_missing?("helpers/#{child.controller_path}_helper")
end
end
# Extract helper names from files in app/helpers/**/*.rb
def all_application_helpers
extract = /^#{Regexp.quote(HELPERS_DIR)}\/?(.*)_helper.rb$/
Dir["#{HELPERS_DIR}/**/*_helper.rb"].map { |file| file.sub extract, '\1' }
end
end
end
end
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