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module ActionController #:nodoc:
module Helpers #:nodoc:
def self.append_features(base)
super
base.class_eval { class << self; alias_method :inherited_without_helper, :inherited; end }
base.extend(ClassMethods)
end
# The template helpers serves to relieve the templates from including the same inline code again and again. It's a
# set of standardized methods for working with forms (FormHelper), dates (DateHelper), texts (TextHelper), and
# Active Records (ActiveRecordHelper) that's available to all templates by default.
#
# It's also really easy to make your own helpers and it's much encouraged to keep the template files free
# from complicated logic. It's even encouraged to bundle common compositions of methods from other helpers
# (often the common helpers) as they're used by the specific application.
#
# module MyHelper
# def hello_world() "hello world" end
# end
#
# MyHelper can now be included in a controller, like this:
#
# class MyController < ActionController::Base
# helper :my_helper
# end
#
# ...and, same as above, used in any template rendered from MyController, like this:
#
# Let's hear what the helper has to say: <tt><%= hello_world %></tt>
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:
template_class.class_eval "include #{helper_module}"
end
# Declare a helper. If you use this method in your controller, you don't
# have to do the +self.append_features+ incantation in your helper class.
# helper :foo
# requires 'foo_helper' and includes FooHelper in the template class.
# helper FooHelper
# includes FooHelper in the template class.
# helper { def foo() "#{bar} is the very best" end }
# evaluates the block in the template class, adding method #foo.
# helper(:three, BlindHelper) { def mice() 'mice' end }
# does all three.
def helper(*args, &block)
args.flatten.each do |arg|
case arg
when Module
add_template_helper(arg)
when String, Symbol
file_name = Inflector.underscore(arg.to_s.downcase) + '_helper'
class_name = Inflector.camelize(file_name)
begin
require_dependency(file_name)
rescue LoadError
raise LoadError, "Missing helper file helpers/#{file_name}.rb"
end
raise ArgumentError, "Missing #{class_name} module in helpers/#{file_name}.rb" unless Object.const_defined?(class_name)
add_template_helper(Object.const_get(class_name))
else
raise ArgumentError, 'helper expects String, Symbol, or Module argument'
end
end
# Evaluate block in template class if given.
template_class.module_eval(&block) if block_given?
end
# Declare a controller method as a helper. For example,
# helper_method :link_to
# def link_to(name, options) ... end
# makes the link_to controller method available in the view.
def helper_method(*methods)
template_class.controller_delegate(*methods)
end
# Declare a controller attribute as a helper. For example,
# helper_attr :name
# attr_accessor :name
# makes the name and name= controller methods available in the view.
# The is a convenience wrapper for helper_method.
def helper_attr(*attrs)
attrs.flatten.each { |attr| helper_method(attr, "#{attr}=") }
end
private
def inherited(child)
inherited_without_helper(child)
begin
child.helper(child.controller_name)
rescue LoadError
# No default helper available for this controller
end
end
end
end
end
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