Methods
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Instance Public methods
clear_helpers()

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

Source: show | on GitHub 

     # File actionpack/lib/abstract_controller/helpers.rb, line 105
105:       def clear_helpers
106:         inherited_helper_methods = _helper_methods
107:         self._helpers = Module.new
108:         self._helper_methods = Array.new
109: 
110:         inherited_helper_methods.each { |meth| helper_method meth }
111:         default_helper_module! unless anonymous?
112:       end
helper(*args, &block)

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

Parameters

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 }

Source: show | on GitHub 

     # File actionpack/lib/abstract_controller/helpers.rb, line 95
 95:       def helper(*args, &block)
 96:         modules_for_helpers(args).each do |mod|
 97:           add_template_helper(mod)
 98:         end
 99: 
100:         _helpers.module_eval(&block) if block_given?
101:       end
helper_method(*meths)

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.

Source: show | on GitHub 

    # File actionpack/lib/abstract_controller/helpers.rb, line 46
46:       def helper_method(*meths)
47:         meths.flatten!
48:         self._helper_methods += meths
49: 
50:         meths.each do |meth|
51:           _helpers.class_eval "def \#{meth}(*args, &blk)\ncontroller.send(%(\#{meth}), *args, &blk)\nend\n", __FILE__, __LINE__ + 1
52:         end
53:       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.

Source: show | on GitHub 

    # File actionpack/lib/abstract_controller/helpers.rb, line 19
19:       def inherited(klass)
20:         helpers = _helpers
21:         klass._helpers = Module.new { include helpers }
22:         klass.class_eval { default_helper_module! unless anonymous? }
23:         super
24:       end
modules_for_helpers(args)

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.
Module:No further processing

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.

Source: show | on GitHub 

     # File actionpack/lib/abstract_controller/helpers.rb, line 131
131:       def modules_for_helpers(args)
132:         args.flatten.map! do |arg|
133:           case arg
134:           when String, Symbol
135:             file_name = "#{arg.to_s.underscore}_helper"
136:             require_dependency(file_name, "Missing helper file helpers/%s.rb")
137:             file_name.camelize.constantize
138:           when Module
139:             arg
140:           else
141:             raise ArgumentError, "helper must be a String, Symbol, or Module"
142:           end
143:         end
144:       end