Class: ActionController::Base

Inherits:
Object
  • Object
show all
Includes:
StatusCodes
Defined in:
lib/action_controller/base.rb,
lib/action_controller/cgi_process.rb,
lib/action_controller/test_process.rb

Overview

Action Controllers are the core of a web request in Rails. They are made up of one or more actions that are executed on request and then either render a template or redirect to another action. An action is defined as a public method on the controller, which will automatically be made accessible to the web-server through Rails Routes.

A sample controller could look like this:

class GuestBookController < ActionController::Base
  def index
    @entries = Entry.find(:all)
  end

  def sign
    Entry.create(params[:entry])
    redirect_to :action => "index"
  end
end

Actions, by default, render a template in the app/views directory corresponding to the name of the controller and action after executing code in the action. For example, the index action of the GuestBookController would render the template app/views/guestbook/index.erb by default after populating the @entries instance variable.

Unlike index, the sign action will not render a template. After performing its main purpose (creating a new entry in the guest book), it initiates a redirect instead. This redirect works by returning an external “302 Moved” HTTP response that takes the user to the index action.

The index and sign represent the two basic action archetypes used in Action Controllers. Get-and-show and do-and-redirect. Most actions are variations of these themes.

Requests

Requests are processed by the Action Controller framework by extracting the value of the “action” key in the request parameters. This value should hold the name of the action to be performed. Once the action has been identified, the remaining request parameters, the session (if one is available), and the full request with all the HTTP headers are made available to the action through instance variables. Then the action is performed.

The full request object is available with the request accessor and is primarily used to query for HTTP headers. These queries are made by accessing the environment hash, like this:

def server_ip
  location = request.env["SERVER_ADDR"]
  render :text => "This server hosted at #{location}"
end

Parameters

All request parameters, whether they come from a GET or POST request, or from the URL, are available through the params method which returns a hash. For example, an action that was performed through /weblog/list?category=All&limit=5 will include { "category" => "All", "limit" => 5 } in params.

It's also possible to construct multi-dimensional parameter hashes by specifying keys using brackets, such as:

<input type="text" name="post[name]" value="david">
<input type="text" name="post[address]" value="hyacintvej">

A request stemming from a form holding these inputs will include { "post" => { "name" => "david", "address" => "hyacintvej" } }. If the address input had been named “post[street]”, the params would have included { "post" => { "address" => { "street" => "hyacintvej" } } }. There's no limit to the depth of the nesting.

Sessions

Sessions allows you to store objects in between requests. This is useful for objects that are not yet ready to be persisted, such as a Signup object constructed in a multi-paged process, or objects that don't change much and are needed all the time, such as a User object for a system that requires login. The session should not be used, however, as a cache for objects where it's likely they could be changed unknowingly. It's usually too much work to keep it all synchronized – something databases already excel at.

You can place objects in the session by using the session method, which accesses a hash:

session[:person] = Person.authenticate(user_name, password)

And retrieved again through the same hash:

Hello #{session[:person]}

For removing objects from the session, you can either assign a single key to nil:

# removes :person from session
session[:person] = nil

or you can remove the entire session with reset_session.

Sessions are stored by default in a browser cookie that's cryptographically signed, but unencrypted. This prevents the user from tampering with the session but also allows him to see its contents.

Do not put secret information in cookie-based sessions!

Other options for session storage are:

  • ActiveRecordStore - Sessions are stored in your database, which works better than PStore with multiple app servers and, unlike CookieStore, hides your session contents from the user. To use ActiveRecordStore, set

    config.action_controller.session_store = :active_record_store
    

    in your config/environment.rb and run rake db:sessions:create.

  • MemCacheStore - Sessions are stored as entries in your memcached cache. Set the session store type in config/environment.rb:

    config.action_controller.session_store = :mem_cache_store
    

    This assumes that memcached has been installed and configured properly. See the MemCacheStore docs for more information.

Responses

Each action results in a response, which holds the headers and document to be sent to the user's browser. The actual response object is generated automatically through the use of renders and redirects and requires no user intervention.

Renders

Action Controller sends content to the user by using one of five rendering methods. The most versatile and common is the rendering of a template. Included in the Action Pack is the Action View, which enables rendering of ERb templates. It's automatically configured. The controller passes objects to the view by assigning instance variables:

def show
  @post = Post.find(params[:id])
end

Which are then automatically available to the view:

Title: <%= @post.title %>

You don't have to rely on the automated rendering. Especially actions that could result in the rendering of different templates will use the manual rendering methods:

def search
  @results = Search.find(params[:query])
  case @results
    when 0 then render :action => "no_results"
    when 1 then render :action => "show"
    when 2..10 then render :action => "show_many"
  end
end

Read more about writing ERb and Builder templates in classes/ActionView/Base.html.

Redirects

Redirects are used to move from one action to another. For example, after a create action, which stores a blog entry to a database, we might like to show the user the new entry. Because we're following good DRY principles (Don't Repeat Yourself), we're going to reuse (and redirect to) a show action that we'll assume has already been created. The code might look like this:

def create
  @entry = Entry.new(params[:entry])
  if @entry.save
    # The entry was saved correctly, redirect to show
    redirect_to :action => 'show', :id => @entry.id
  else
    # things didn't go so well, do something else
  end
end

In this case, after saving our new entry to the database, the user is redirected to the show method which is then executed.

Calling multiple redirects or renders

An action may contain only a single render or a single redirect. Attempting to try to do either again will result in a DoubleRenderError:

def do_something
  redirect_to :action => "elsewhere"
  render :action => "overthere" # raises DoubleRenderError
end

If you need to redirect on the condition of something, then be sure to add “and return” to halt execution.

def do_something
  redirect_to(:action => "elsewhere") and return if monkeys.nil?
  render :action => "overthere" # won't be called if monkeys is nil
end

Direct Known Subclasses

ActionView::TestCase::TestController

Constant Summary collapse

DEFAULT_RENDER_STATUS_CODE =
"200 OK"
@@protected_instance_variables =

Controller specific instance variables which will not be accessible inside views.

%w(@assigns @performed_redirect @performed_render @variables_added @request_origin @url @parent_controller
@action_name @before_filter_chain_aborted @action_cache_path @_session @_cookies @_headers @_params
@_flash @_response)
@@asset_host =

Prepends all the URL-generating helpers from AssetHelper. This makes it possible to easily move javascripts, stylesheets, and images to a dedicated asset server away from the main web server. Example:

ActionController::Base.asset_host = "http://assets.example.com"
""
@@consider_all_requests_local =

All requests are considered local by default, so everyone will be exposed to detailed debugging screens on errors. When the application is ready to go public, this should be set to false, and the protected method local_request? should instead be implemented in the controller to determine when debugging screens should be shown.

true
@@allow_concurrency =

Indicates whether to allow concurrent action processing. Your controller actions and any other code they call must also behave well when called from concurrent threads. Turned off by default.

false
@@param_parsers =

Modern REST web services often need to submit complex data to the web application. The @@param_parsers hash lets you register handlers which will process the HTTP body and add parameters to the params hash. These handlers are invoked for POST and PUT requests.

By default application/xml is enabled. A XmlSimple class with the same param name as the root will be instantiated in the params. This allows XML requests to mask themselves as regular form submissions, so you can have one action serve both regular forms and web service requests.

Example of doing your own parser for a custom content type:

ActionController::Base.param_parsers[Mime::Type.lookup('application/atom+xml')] = Proc.new do |data|
   node = REXML::Document.new(post)
  { node.root.name => node.root }
end

Note: Up until release 1.1 of Rails, Action Controller would default to using XmlSimple configured to discard the root node for such requests. The new default is to keep the root, such that “<r><name>David</name></r>” results in params[:r][:name] for “David” instead of params[:name]. To get the old behavior, you can re-register XmlSimple as application/xml handler ike this:

ActionController::Base.param_parsers[Mime::XML] =
  Proc.new { |data| XmlSimple.xml_in(data, 'ForceArray' => false) }

A YAML parser is also available and can be turned on with:

ActionController::Base.param_parsers[Mime::YAML] = :yaml
{ Mime::MULTIPART_FORM   => :multipart_form,
Mime::URL_ENCODED_FORM => :url_encoded_form,
Mime::XML              => :xml_simple,
Mime::JSON             => :json }
@@default_charset =

Controls the default charset for all renders.

"utf-8"
@@resource_action_separator =

Controls the resource action separator

"/"
@@resources_path_names =

Allow to override path names for default resources' actions

{ :new => 'new', :edit => 'edit' }

Constants included from StatusCodes

StatusCodes::STATUS_CODES, StatusCodes::SYMBOL_TO_STATUS_CODE

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#action_nameObject

Returns the name of the action this controller is processing.


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# File 'lib/action_controller/base.rb', line 387

def action_name
  @action_name
end

#assignsObject (readonly)

Returns the value of attribute assigns


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# File 'lib/action_controller/test_process.rb', line 6

def assigns
  @assigns
end

Class Method Details

.append_view_path(path) ⇒ Object

Adds a view_path to the end of the view_paths array. If the current class has no view paths, copy them from the superclass. This change will be visible for all future requests.

ArticleController.append_view_path("views/default")
ArticleController.append_view_path(["views/default", "views/custom"])

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# File 'lib/action_controller/base.rb', line 456

def append_view_path(path)
  @view_paths = superclass.view_paths.dup if @view_paths.nil?
  @view_paths.push(*path)
end

.controller_class_nameObject

Converts the class name from something like “OneModule::TwoModule::NeatController” to “NeatController”.


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# File 'lib/action_controller/base.rb', line 396

def controller_class_name
  @controller_class_name ||= name.demodulize
end

.controller_nameObject

Converts the class name from something like “OneModule::TwoModule::NeatController” to “neat”.


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# File 'lib/action_controller/base.rb', line 401

def controller_name
  @controller_name ||= controller_class_name.sub(/Controller$/, '').underscore
end

.controller_pathObject

Converts the class name from something like “OneModule::TwoModule::NeatController” to “one_module/two_module/neat”.


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# File 'lib/action_controller/base.rb', line 406

def controller_path
  @controller_path ||= name.gsub(/Controller$/, '').underscore
end

.filter_parameter_logging(*filter_words, &block) ⇒ Object

Replace sensitive parameter data from the request log. Filters parameters that have any of the arguments as a substring. Looks in all subhashes of the param hash for keys to filter. If a block is given, each key and value of the parameter hash and all subhashes is passed to it, the value or key can be replaced using String#replace or similar method.

Examples:

filter_parameter_logging
=> Does nothing, just slows the logging process down

filter_parameter_logging :password
=> replaces the value to all keys matching /password/i with "[FILTERED]"

filter_parameter_logging :foo, "bar"
=> replaces the value to all keys matching /foo|bar/i with "[FILTERED]"

filter_parameter_logging { |k,v| v.reverse! if k =~ /secret/i }
=> reverses the value to all keys matching /secret/i

filter_parameter_logging(:foo, "bar") { |k,v| v.reverse! if k =~ /secret/i }
=> reverses the value to all keys matching /secret/i, and
   replaces the value to all keys matching /foo|bar/i with "[FILTERED]"

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# File 'lib/action_controller/base.rb', line 484

def filter_parameter_logging(*filter_words, &block)
  parameter_filter = Regexp.new(filter_words.collect{ |s| s.to_s }.join('|'), true) if filter_words.length > 0

  define_method(:filter_parameters) do |unfiltered_parameters|
    filtered_parameters = {}

    unfiltered_parameters.each do |key, value|
      if key =~ parameter_filter
        filtered_parameters[key] = '[FILTERED]'
      elsif value.is_a?(Hash)
        filtered_parameters[key] = filter_parameters(value)
      elsif block_given?
        key = key.dup
        value = value.dup if value
        yield key, value
        filtered_parameters[key] = value
      else
        filtered_parameters[key] = value
      end
    end

    filtered_parameters
  end
  protected :filter_parameters
end

.hidden_actionsObject

Return an array containing the names of public methods that have been marked hidden from the action processor. By default, all methods defined in ActionController::Base and included modules are hidden. More methods can be hidden using hide_actions.


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# File 'lib/action_controller/base.rb', line 413

def hidden_actions
  read_inheritable_attribute(:hidden_actions) || write_inheritable_attribute(:hidden_actions, [])
end

.hide_action(*names) ⇒ Object

Hide each of the given methods from being callable as actions.


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# File 'lib/action_controller/base.rb', line 418

def hide_action(*names)
  write_inheritable_attribute(:hidden_actions, hidden_actions | names.map { |name| name.to_s })
end

.prepend_view_path(path) ⇒ Object

Adds a view_path to the front of the view_paths array. If the current class has no view paths, copy them from the superclass. This change will be visible for all future requests.

ArticleController.prepend_view_path("views/default")
ArticleController.prepend_view_path(["views/default", "views/custom"])

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# File 'lib/action_controller/base.rb', line 444

def prepend_view_path(path)
  @view_paths = superclass.view_paths.dup if !defined?(@view_paths) || @view_paths.nil?
  @view_paths.unshift(*path)
end

.process(request, response) ⇒ Object

Factory for the standard create, process loop where the controller is discarded after processing.


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# File 'lib/action_controller/base.rb', line 391

def process(request, response) #:nodoc:
  new.process(request, response)
end

.process_cgi(cgi = CGI.new, session_options = {}) ⇒ Object

Process a request extracted from a CGI object and return a response. Pass false as session_options to disable sessions (large performance increase if sessions are not needed). The session_options are the same as for CGI::Session:

  • :database_manager - standard options are CGI::Session::FileStore, CGI::Session::MemoryStore, and CGI::Session::PStore (default). Additionally, there is CGI::Session::DRbStore and CGI::Session::ActiveRecordStore. Read more about these in lib/action_controller/session.

  • :session_key - the parameter name used for the session id. Defaults to '_session_id'.

  • :session_id - the session id to use. If not provided, then it is retrieved from the session_key cookie, or automatically generated for a new session.

  • :new_session - if true, force creation of a new session. If not set, a new session is only created if none currently exists. If false, a new session is never created, and if none currently exists and the session_id option is not set, an ArgumentError is raised.

  • :session_expires - the time the current session expires, as a Time object. If not set, the session will continue indefinitely.

  • :session_domain - the hostname domain for which this session is valid. If not set, defaults to the hostname of the server.

  • :session_secure - if true, this session will only work over HTTPS.

  • :session_path - the path for which this session applies. Defaults to the directory of the CGI script.

  • :cookie_only - if true (the default), session IDs will only be accepted from cookies and not from the query string or POST parameters. This protects against session fixation attacks.


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# File 'lib/action_controller/cgi_process.rb', line 26

def self.process_cgi(cgi = CGI.new, session_options = {})
  new.process_cgi(cgi, session_options)
end

.process_test(request) ⇒ Object

Process a test request called with a TestRequest object.


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# File 'lib/action_controller/test_process.rb', line 9

def self.process_test(request)
  new.process_test(request)
end

.view_pathsObject

View load paths determine the bases from which template references can be made. So a call to render(“test/template”) will be looked up in the view load paths array and the closest match will be returned.


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# File 'lib/action_controller/base.rb', line 425

def view_paths
  if defined? @view_paths
    @view_paths
  else
    superclass.view_paths
  end
end

.view_paths=(value) ⇒ Object


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# File 'lib/action_controller/base.rb', line 433

def view_paths=(value)
  @view_paths = ActionView::Base.process_view_paths(value) if value
end

Instance Method Details

#append_view_path(path) ⇒ Object

Adds a view_path to the end of the view_paths array. This change affects the current request only.

self.append_view_path("views/default")
self.append_view_path(["views/default", "views/custom"])

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# File 'lib/action_controller/base.rb', line 678

def append_view_path(path)
  @template.view_paths.push(*path)
end

#controller_class_nameObject

Converts the class name from something like “OneModule::TwoModule::NeatController” to “NeatController”.


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# File 'lib/action_controller/base.rb', line 633

def controller_class_name
  self.class.controller_class_name
end

#controller_nameObject

Converts the class name from something like “OneModule::TwoModule::NeatController” to “neat”.


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# File 'lib/action_controller/base.rb', line 638

def controller_name
  self.class.controller_name
end

#controller_pathObject

Converts the class name from something like “OneModule::TwoModule::NeatController” to “one_module/two_module/neat”.


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# File 'lib/action_controller/base.rb', line 643

def controller_path
  self.class.controller_path
end

#prepend_view_path(path) ⇒ Object

Adds a view_path to the front of the view_paths array. This change affects the current request only.

self.prepend_view_path("views/default")
self.prepend_view_path(["views/default", "views/custom"])

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# File 'lib/action_controller/base.rb', line 668

def prepend_view_path(path)
  @template.view_paths.unshift(*path)
end

#process(request, response, method = :perform_action, *arguments) ⇒ Object

Extracts the action_name from the request parameters and performs that action.


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# File 'lib/action_controller/base.rb', line 515

def process(request, response, method = :perform_action, *arguments) #:nodoc:
  response.request = request

  initialize_template_class(response)
  assign_shortcuts(request, response)
  initialize_current_url
  assign_names

  log_processing
  send(method, *arguments)

  send_response
ensure
  process_cleanup
end

#process_cgi(cgi, session_options = {}) ⇒ Object

:nodoc:


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# File 'lib/action_controller/cgi_process.rb', line 30

def process_cgi(cgi, session_options = {}) #:nodoc:
  process(CgiRequest.new(cgi, session_options), CgiResponse.new(cgi)).out
end

#process_test(request) ⇒ Object

:nodoc:


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# File 'lib/action_controller/test_process.rb', line 13

def process_test(request) #:nodoc:
  process(request, TestResponse.new)
end

#process_with_test(*args) ⇒ Object


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# File 'lib/action_controller/test_process.rb', line 17

def process_with_test(*args)
  returning process_without_test(*args) do
    @assigns = {}
    (instance_variable_names - @@protected_instance_variables).each do |var|
      value = instance_variable_get(var)
      @assigns[var[1..-1]] = value
      response.template.assigns[var[1..-1]] = value if response
    end
  end
end

#send_responseObject


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# File 'lib/action_controller/base.rb', line 531

def send_response
  response.prepare! unless component_request?
  response
end

#session_enabled?Boolean

Returns:

  • (Boolean)

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# File 'lib/action_controller/base.rb', line 647

def session_enabled?
  request.session_options && request.session_options[:disabled] != false
end

#url_for(options = {}) ⇒ Object

Returns a URL that has been rewritten according to the options hash and the defined routes. (For doing a complete redirect, use redirect_to).

url_for is used to:

All keys given to url_for are forwarded to the Route module, save for the following:

  • :anchor - Specifies the anchor name to be appended to the path. For example, url_for :controller => 'posts', :action => 'show', :id => 10, :anchor => 'comments' will produce “/posts/show/10#comments”.

  • :only_path - If true, returns the relative URL (omitting the protocol, host name, and port) (false by default).

  • :trailing_slash - If true, adds a trailing slash, as in “/archive/2005/”. Note that this is currently not recommended since it breaks caching.

  • :host - Overrides the default (current) host if provided.

  • :protocol - Overrides the default (current) protocol if provided.

  • :port - Optionally specify the port to connect to.

  • :user - Inline HTTP authentication (only plucked out if :password is also present).

  • :password - Inline HTTP authentication (only plucked out if :user is also present).

  • :skip_relative_url_root - If true, the url is not constructed using the relative_url_root of the request so the path will include the web server relative installation directory.

The URL is generated from the remaining keys in the hash. A URL contains two key parts: the <base> and a query string. Routes composes a query string as the key/value pairs not included in the <base>.

The default Routes setup supports a typical Rails path of “controller/action/id” where action and id are optional, with action defaulting to 'index' when not given. Here are some typical url_for statements and their corresponding URLs:

url_for :controller => 'posts', :action => 'recent'                # => 'proto://host.com/posts/recent'
url_for :controller => 'posts', :action => 'index'                 # => 'proto://host.com/posts'
url_for :controller => 'posts', :action => 'index', :port=>'8033'  # => 'proto://host.com:8033/posts'
url_for :controller => 'posts', :action => 'show', :id => 10       # => 'proto://host.com/posts/show/10'
url_for :controller => 'posts', :user => 'd', :password => '123'   # => 'proto://d:[email protected]/posts'

When generating a new URL, missing values may be filled in from the current request's parameters. For example, url_for :action => 'some_action' will retain the current controller, as expected. This behavior extends to other parameters, including :controller, :id, and any other parameters that are placed into a Route's path.   The URL helpers such as url_for have a limited form of memory: when generating a new URL, they can look for missing values in the current request's parameters. Routes attempts to guess when a value should and should not be taken from the defaults. There are a few simple rules on how this is performed:

  • If the controller name begins with a slash no defaults are used:

    url_for :controller => '/home'
    

    In particular, a leading slash ensures no namespace is assumed. Thus, while url_for :controller => 'users' may resolve to Admin::UsersController if the current controller lives under that module, url_for :controller => '/users' ensures you link to ::UsersController no matter what.

  • If the controller changes, the action will default to index unless provided

The final rule is applied while the URL is being generated and is best illustrated by an example. Let us consider the route given by map.connect 'people/:last/:first/:action', :action => 'bio', :controller => 'people'.

Suppose that the current URL is “people/hh/david/contacts”. Let's consider a few different cases of URLs which are generated from this page.

  • url_for :action => 'bio' – During the generation of this URL, default values will be used for the first and

last components, and the action shall change. The generated URL will be, “people/hh/david/bio”.

  • url_for :first => 'davids-little-brother' This generates the URL 'people/hh/davids-little-brother' – note that this URL leaves out the assumed action of 'bio'.

However, you might ask why the action from the current request, 'contacts', isn't carried over into the new URL. The answer has to do with the order in which the parameters appear in the generated path. In a nutshell, since the value that appears in the slot for :first is not equal to default value for :first we stop using defaults. On its own, this rule can account for much of the typical Rails URL behavior.   Although a convenience, defaults can occasionally get in your way. In some cases a default persists longer than desired. The default may be cleared by adding :name => nil to url_for's options. This is often required when writing form helpers, since the defaults in play may vary greatly depending upon where the helper is used from. The following line will redirect to PostController's default action, regardless of the page it is displayed on:

url_for :controller => 'posts', :action => nil

If you explicitly want to create a URL that's almost the same as the current URL, you can do so using the :overwrite_params options. Say for your posts you have different views for showing and printing them. Then, in the show view, you get the URL for the print view like this

url_for :overwrite_params => { :action => 'print' }

This takes the current URL as is and only exchanges the action. In contrast, url_for :action => 'print' would have slashed-off the path components after the changed action.


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# File 'lib/action_controller/base.rb', line 620

def url_for(options = {})
  options ||= {}
  case options
    when String
      options
    when Hash
      @url.rewrite(rewrite_options(options))
    else
      polymorphic_url(options)
  end
end

#view_pathsObject

View load paths for controller.


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# File 'lib/action_controller/base.rb', line 654

def view_paths
  @template.view_paths
end

#view_paths=(value) ⇒ Object


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# File 'lib/action_controller/base.rb', line 658

def view_paths=(value)
  @template.view_paths = ActionView::Base.process_view_paths(value)
end