Clears up all existing helpers in this class, only keeping the helper with the same name as this class.
# File actionpack/lib/abstract_controller/helpers.rb, line 118 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
The helper
class method can take a series of helper module
names, a block, or both.
Options
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 }
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.
# File actionpack/lib/abstract_controller/helpers.rb, line 61 def helper_method(*meths) meths.flatten! self._helper_methods += meths meths.each do |meth| _helpers.class_eval " def #{meth}(*args, &blk) # def current_user(*args, &blk) controller.send(%(#{meth}), *args, &blk) # controller.send(:current_user, *args, &blk) end # end ", __FILE__, __LINE__ + 1 end 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.
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.
- 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.
# File actionpack/lib/abstract_controller/helpers.rb, line 144 def modules_for_helpers(args) args.flatten.map! do |arg| case arg when String, Symbol file_name = "#{arg.to_s.underscore}_helper" begin require_dependency(file_name) rescue LoadError => e raise AbstractController::Helpers::MissingHelperError.new(e, file_name) end mod_name = file_name.camelize begin mod_name.constantize rescue LoadError # dependencies.rb gives a similar error message but its wording is # not as clear because it mentions autoloading. To the user all it # matters is that a helper module couldn't be loaded, autoloading # is an internal mechanism that should not leak. raise NameError, "Couldn't find #{mod_name}, expected it to be defined in helpers/#{file_name}.rb" end when Module arg else raise ArgumentError, "helper must be a String, Symbol, or Module" end end end