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module AbstractController::Helpers::ClassMethods

Attributes

_helpers[W]

Public Instance Methods

_helpers_for_modification() Show source

# File actionpack/lib/abstract_controller/helpers.rb, line 184
def _helpers_for_modification
  unless @_helpers
    self._helpers = define_helpers_module(self, superclass._helpers)
  end
  _helpers
end

clear_helpers() Show source

# File actionpack/lib/abstract_controller/helpers.rb, line 158
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

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

helper(*args, &block) Show source

# File actionpack/lib/abstract_controller/helpers.rb, line 147
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

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

helper_method(*methods) Show source

# File actionpack/lib/abstract_controller/helpers.rb, line 79
      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}')
          ruby_eval
        end
      end

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.

inherited(klass) Show source

# File actionpack/lib/abstract_controller/helpers.rb, line 48
def inherited(klass)
  # Inherited from parent by default
  klass._helpers = nil

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

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.

Calls superclass method

modules_for_helpers(modules_or_helper_prefixes) Show source

# File actionpack/lib/abstract_controller/helpers.rb, line 169
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

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