AbstractController::Helpers::ClassMethods

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

     # File lib/abstract_controller/helpers.rb, line 106
106:       def clear_helpers
107:         inherited_helper_methods = _helper_methods
108:         self._helpers = Module.new
109:         self._helper_methods = Array.new
110: 
111:         inherited_helper_methods.each { |meth| helper_method meth }
112:         default_helper_module! unless anonymous?
113:       end

The helper class method can take a series of helper module names, a block, or both.

Parameters

• *args - Module, Symbol, String, :all

• block - A block defining helper methods

Examples

When the argument is a module it will be included directly in the template class.

  helper FooHelper # => includes FooHelper

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

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 }

     # File lib/abstract_controller/helpers.rb, line 96
 96:       def helper(*args, &block)
 97:         modules_for_helpers(args).each do |mod|
 98:           add_template_helper(mod)
 99:         end
100: 
101:         _helpers.module_eval(&block) if block_given?
102:       end

Declare a controller method as a helper. For example, the following makes the current_user controller method 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.

    # File lib/abstract_controller/helpers.rb, line 48
48:       def helper_method(*meths)
49:         meths.flatten!
50:         self._helper_methods += meths
51: 
52:         meths.each do |meth|
53:           _helpers.class_eval             def #{meth}(*args, &blk)              controller.send(%(#{meth}), *args, &blk)            end, __FILE__, __LINE__ + 1
54:         end
55:       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.

    # File lib/abstract_controller/helpers.rb, line 21
21:       def inherited(klass)
22:         helpers = _helpers
23:         klass._helpers = Module.new { include helpers }
24:         klass.class_eval { default_helper_module! unless anonymous? }
25:         super
26:       end

Makes all the (instance) methods in the helper module available to templates rendered through this controller.

Parameters

• module - The module to include into the current helper module for the class

     # File lib/abstract_controller/helpers.rb, line 122
122:       def add_template_helper(mod)
123:         _helpers.module_eval { include mod }
124:       end

Returns a list of modules, normalized from the acceptable kinds of helpers with the following behavior:

  and "foo_bar_helper.rb" is loaded using require_dependency.

After loading the appropriate files, the corresponding modules are returned.

Parameters

• args - An array of helpers

Returns

• Array - A normalized list of modules for the list of helpers provided.

     # File lib/abstract_controller/helpers.rb, line 143
143:       def modules_for_helpers(args)
144:         args.flatten.map! do |arg|
145:           case arg
146:           when String, Symbol
147:             file_name = "#{arg.to_s.underscore}_helper"
148:             require_dependency(file_name, "Missing helper file helpers/%s.rb")
149:             file_name.camelize.constantize
150:           when Module
151:             arg
152:           else
153:             raise ArgumentError, "helper must be a String, Symbol, or Module"
154:           end
155:         end
156:       end