Module: AbstractController::Helpers::ClassMethods

Relationships & Source Files
Defined in:	actionpack/lib/abstract_controller/helpers.rb

Instance Attribute Summary

#_helpers=(value) writeonly

Instance Method Summary

#_helpers_for_modification
#clear_helpers

Clears up all existing helpers in this class, only keeping the helper with the same name as this class.
#helper(*args, &block)

Includes the given modules in the template class.
#helper_method(*methods)

Declare a controller method as a helper.
#inherited(klass)

When a class is inherited, wrap its helper module in a new module.
#modules_for_helpers(modules_or_helper_prefixes)

Given an array of values like the ones accepted by #helper, this method returns an array with the corresponding modules, in the same order.

Instance Attribute Details

#_helpers=(value) (writeonly)

[ GitHub ]

# File 'actionpack/lib/abstract_controller/helpers.rb', line 55


attr_writer :_helpers

Instance Method Details

#_helpers_for_modification

[ GitHub ]

# File 'actionpack/lib/abstract_controller/helpers.rb', line 183


def _helpers_for_modification
  unless @_helpers
    self._helpers = define_helpers_module(self, superclass._helpers)
  end
  _helpers
end

#clear_helpers

Clears up all existing helpers in this class, only keeping the helper with the same name as this class.

[ GitHub ]

# File 'actionpack/lib/abstract_controller/helpers.rb', line 157


def clear_helpers
  inherited_helper_methods = _helper_methods
  self._helpers = Module.new
  self._helper_methods = Array.new

  inherited_helper_methods.each { |meth| helper_method meth }
  default_helper_module! unless anonymous?
end

#helper(*args, &block)

Includes the given modules in the template class.

Modules can be specified in different ways. All of the following calls include FooHelper:

# Module, recommended.
helper FooHelper

# String/symbol without the "helper" suffix, camel or snake case.
helper "Foo"
helper :Foo
helper "foo"
helper :foo

The last two assume that "foo".camelize returns “Foo”.

When strings or symbols are passed, the method finds the actual module object using String#constantize. Therefore, if the module has not been yet loaded, it has to be autoloadable, which is normally the case.

Namespaces are supported. The following calls include Foo::BarHelper:

# Module, recommended.
helper Foo::BarHelper

# String/symbol without the "helper" suffix, camel or snake case.
helper "Foo::Bar"
helper :"Foo::Bar"
helper "foo/bar"
helper :"foo/bar"

The last two assume that "foo/bar".camelize returns “Foo::Bar”.

The method accepts a block too. If present, the block is evaluated in the context of the controller helper module. This simple call makes the wadus method available in templates of the enclosing controller:

helper do
  def wadus
    "wadus"
  end
end

Furthermore, all the above styles can be mixed together:

helper FooHelper, "woo", "bar/baz" do
  def wadus
    "wadus"
  end
end

[ GitHub ]

# File 'actionpack/lib/abstract_controller/helpers.rb', line 146


def helper(*args, &block)
  modules_for_helpers(args).each do |mod|
    next if _helpers.include?(mod)
    _helpers_for_modification.include(mod)
  end

  _helpers_for_modification.module_eval(&block) if block_given?
end

#helper_method(*methods)

Declare a controller method as a helper. For example, the following makes the current_user and logged_in? controller methods available to the view:

class ApplicationController < ActionController::Base
  helper_method :current_user, :logged_in?

  def current_user
    @current_user ||= User.find_by(id: session[:user])
  end

  def logged_in?
    current_user != nil
  end
end

In a view:

<% if logged_in? -%>Welcome, <%= current_user.name %><% end -%>

Parameters

method[, method] - A name or names of a method on the controller to be made available on the view.

[ GitHub ]

# File 'actionpack/lib/abstract_controller/helpers.rb', line 78


def helper_method(*methods)
  methods.flatten!
  self._helper_methods += methods

  location = caller_locations(1, 1).first
  file, line = location.path, location.lineno

  methods.each do |method|
    _helpers_for_modification.class_eval <<-ruby_eval, file, line
      def #{method}(*args, &block)                    # def current_user(*args, &block)
        controller.send(:'#{method}', *args, &block)  #   controller.send(:'current_user', *args, &block)
      end                                             # end
      ruby2_keywords(:'#{method}') if respond_to?(:ruby2_keywords, true)
    ruby_eval
  end
end

#inherited(klass)

When a class is inherited, wrap its helper module in a new module. This ensures that the parent class’s module can be changed independently of the child class’s.

[ GitHub ]

# File 'actionpack/lib/abstract_controller/helpers.rb', line 47


def inherited(klass)
  # Inherited from parent by default
  klass._helpers = nil

  klass.class_eval { default_helper_module! } unless klass.anonymous?
  super
end

#modules_for_helpers(modules_or_helper_prefixes)

Given an array of values like the ones accepted by #helper, this method returns an array with the corresponding modules, in the same order.

[ GitHub ]

# File 'actionpack/lib/abstract_controller/helpers.rb', line 168


def modules_for_helpers(modules_or_helper_prefixes)
  modules_or_helper_prefixes.flatten.map! do |module_or_helper_prefix|
    case module_or_helper_prefix
    when Module
      module_or_helper_prefix
    when String, Symbol
      helper_prefix = module_or_helper_prefix.to_s
      helper_prefix = helper_prefix.camelize unless helper_prefix.start_with?(/[A-Z]/)
      "#{helper_prefix}Helper".constantize
    else
      raise ArgumentError, "helper must be a String, Symbol, or Module"
    end
  end
end