Section 5.5. Controllers

5.5. Controllers

5.5.1. Controller Methods

Each public method in a controller is callable by the default URL scheme /controller/action ( /world/hello , in this example):

 class WorldController < ApplicationController def hello   render :text => 'Hello world' end 

All request parameters, whether they come from a GET or POST request, or from the URL, are available through the params hash:

 /world/hello/1?foo=bar id = params[:id]     # 1 foo = params[:foo]   # bar 

Instance variables defined in the controller's methods are available to the corresponding view templates:

 def show   @person = Person.find( params[:id]) end 

Determine the type of response accepted:

 def index   @posts = Post.find :all   respond_to do type     type.html # using defaults, which will render weblog/index.rhtml     type.xml  { render :action => "index.rxml" }     type.js   { render :action => "index.rjs" }   end end 

Learn more: http://api.rubyonrails.com/classes/ActionController/Base.html.

5.5.2. Render

Usually the view template with the same name as the controller method is used to render the results.

5.5.3. Action

 render :action => 'some_action'   # the default. Does not need to be specified                                   # in a controller method called "some_action" render :action => 'another_action', :layout => false render :action => 'some_action', :layout => 'another_layout' 

5.5.4. Partials

Partials are stored in files whose filename begins with an underscore (like _error , _subform , and _listitem ):

 render :partial => 'subform' render :partial => 'error', :status => 500 render :partial => 'subform', :locals => { :variable => @other_variable } render :partial => 'listitem', :collection => @list render :partial => 'listitem', :collection => @list, :spacer_template => 'list_divider' 

5.5.5. Templates

Similar to rendering an action, but finds the template based on the template root ( app/views ):

 render :template => 'weblog/show'  # renders app/views/weblog/show 

5.5.6. Files

 render :file => '/path/to/some/file.rhtml' render :file => '/path/to/some/filenotfound.rhtml', status => 404, :layout => true 

5.5.7. Text

 render :text => "Hello World" render :text => "This is an error", :status => 500 render :text => "Let's use a layout", :layout => true render :text => 'Specific layout', :layout => 'special' 

5.5.8. Inline Template

Uses ERb to render the " miniature " template:

 render :inline => "<%= 'hello, ' * 3 + 'again' %>" render :inline => "<%= 'hello ' + name %>", :locals => { :name => "david" } 

5.5.9. RJS

 def refresh   render :update do page     page.replace_html  'user_list', :partial => 'user', :collection => @users     page.visual_effect :highlight, 'user_list'   end end 

5.5.10. Change content_type

 render :action => "atom.rxml", :content_type => "application/atom+xml" 

5.5.11. Redirects

 redirect_to(:action => "edit") redirect_to(:controller => "accounts", :action => "signup") 

5.5.12. Nothing

 render :nothing render :nothing, :status => 403    # forbidden 

Learn more:

• http://api.rubyonrails.com/classes/ActionView/Base.html

• http://api.rubyonrails.com/classes/ActionController/Base.html

5.5.13. URL Routing

In config/routes.rb :

 map.connect '', :controller => 'posts', :action => 'list' # default map.connect ':action/:controller/:id' map.connect 'tasks/:year/:month', :controller => 'tasks',                                   :action => 'by_date',                                   :month => nil, :year => nil,                                   :requirements => {:year => //d{4}/,                                                     :month => //d{1,2}/ } 

Learn more: http://manuals.rubyonrails.com/read/chapter/65.

5.5.14. Filter

Filters can change a request before or after the controller. They can, for example, be used for authentication, encryption, or compression:

 before_filter :login_required, :except => [ :login ] before_filter :autenticate, :only => [ :edit, :delete ] after_filter :compress 

It's also possible to use a proc for a really small filter action:

 before_filter { controller false if controller.params["stop_action"] } 

Change the order of your filters by using prepend_before_filter and prepend_after_filter (like prepend_before_filter :some_filter , which will put the some_filter at the beginning of the filter chain).

If you define a filter in a superclass, you can skip it in the subclass:

 skip_before_filter :some_filter skip_after_filter :some_filter 

Learn more: http://api.rubyonrails.com/classes/ActionController/Filters/ClassMethods.html.

5.5.15. Session/Flash

To save data across multiple requests , you can use either the session or the flash hashes. A flash stores a value (normally text) until the next request, while a session stores data during the complete session.

 session[:user] = @user flash[:message] = "Data was saved successfully" <%= link_to "login", :action => 'login' unless session[:user] %> <% if flash[:message] %> <div><%= h flash[:message] %></div> <% end %> 

5.5.15.1. Session management

It's possible to turn off session management:

 session :off                        # turn session managment off session :off, :only => :action      # only for this :action session :off, :except => :action    # except for this action session :only => :foo,              # only for :foo when doing HTTPS         :session_secure => true session :off, :only => :foo,        # off for foo, if uses as Web Service         :if => Proc.new { req req.parameters[:ws] } 

Learn more at the following site: http://api.rubyonrails.com/classes/ActionController/SessionManagement/ClassMethods.html.

5.5.16. Cookies

5.5.16.1. Setting

 cookies[:user_name] = "david" # => Will set a simple session cookie cookies[:login] = { :value => "XJ-122", :expires => Time.now + 3600}     # => Will set a cookie that expires in 1 hour 

5.5.16.2. Reading

 cookies[:user_name] # => "david" cookies.size         # => 2 

5.5.16.3. Deleting

 cookies.delete :user_name 

Option symbols for setting cookies:

value

The cookie's value or list of values (as an array).

path

The path for which this cookie applies (defaults to the root of the application).

domain

The domain for which this cookie applies.

expires

The time at which this cookie expires, as a Time object.

secure

Whether this cookie is a secure cookie (defaults to false ). Secure cookies are transmitted only to HTTPS servers.

Learn more: http://api.rubyonrails.com/classes/ActionController/Cookies.html.