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Diffstat (limited to 'actionpack/lib/action_controller/metal/helpers.rb')
| -rw-r--r-- | actionpack/lib/action_controller/metal/helpers.rb | 176 |
1 files changed, 176 insertions, 0 deletions
diff --git a/actionpack/lib/action_controller/metal/helpers.rb b/actionpack/lib/action_controller/metal/helpers.rb new file mode 100644 index 0000000000..7c52779064 --- /dev/null +++ b/actionpack/lib/action_controller/metal/helpers.rb @@ -0,0 +1,176 @@ +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 |