Methods

Attributes

[W] _helpers

Instance Public methods

all_helpers_from_path(path)

Returns a list of helper names in a given path.

ActionController::Base.all_helpers_from_path 'app/helpers'
# => ["application", "chart", "rubygems"]
πŸ”Ž See on GitHub

_helpers_for_modification()

πŸ“ Source code 
# File actionpack/lib/abstract_controller/helpers.rb, line 218
      def _helpers_for_modification
        unless @_helpers
          self._helpers = define_helpers_module(self, superclass._helpers)
        end
        _helpers
      end
πŸ”Ž See on GitHub

clear_helpers()

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

πŸ“ Source code 
# File actionpack/lib/abstract_controller/helpers.rb, line 209
      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
πŸ”Ž See on GitHub

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 β€œFoo”.

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 β€œFoo::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
πŸ“ Source code 
# File actionpack/lib/abstract_controller/helpers.rb, line 198
      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
πŸ”Ž See on GitHub

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?

  private
    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.

πŸ“ Source code 
# File actionpack/lib/abstract_controller/helpers.rb, line 128
      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|
          # def current_user(...)
          #   controller.send(:'current_user', ...)
          # end
          _helpers_for_modification.class_eval <<~ruby_eval.lines.map(&:strip).join(";"), file, line
            def #{method}(...)
              controller.send(:'#{method}', ...)
            end
          ruby_eval
        end
      end
πŸ”Ž See on GitHub

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.

πŸ“ Source code 
# File actionpack/lib/abstract_controller/helpers.rb, line 68
      def inherited(klass)
        # Inherited from parent by default
        klass._helpers = nil

        klass.class_eval { default_helper_module! } unless klass.anonymous?
        super
      end
πŸ”Ž See on GitHub

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.

ActionController::Base.modules_for_helpers(["application", "chart", "rubygems"])
# => [ApplicationHelper, ChartHelper, RubygemsHelper]
πŸ”Ž See on GitHub