Class: ActionController::Base
- Includes:
- ClassInheritableAttributes
- Defined in:
- lib/action_controller/base.rb,
lib/action_controller/cgi_process.rb,
lib/action_controller/test_process.rb
Overview
Action Controllers are made up of one or more actions that performs its purpose and then either renders a template or redirects 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 a mod_rewrite mapping. 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
GuestBookController.template_root = "templates/"
GuestBookController.process_cgi
All actions assume that you want to render a template matching the name of the action at the end of the performance unless you tell it otherwise. The index action complies with this assumption, so after populating the @entries instance variable, the GuestBookController will render “templates/guestbook/index.rhtml”.
Unlike index, the sign action isn’t interested in rendering a template. So after performing its main purpose (creating a new entry in the guest book), it sheds the rendering assumption and 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.
Also note that it’s the final call to process_cgi
that actually initiates the action performance. It will extract request and response objects from the CGI
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 in @request and is primarily used to query for http headers. These queries are made by accessing the environment hash, like this:
def hello_ip
location = @request.env["REMOTE_IP"]
render_text "Hello stranger from #{location}"
end
Parameters
All request parameters whether they come from a GET or POST request, or from the URL, are available through the @params hash. So 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 memory 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
hash:
@session["person"] = Person.authenticate(user_name, password)
And retrieved again through the same hash:
Hello #{@session["person"]}
Any object can be placed in the session (as long as it can be Marshalled). But remember that 1000 active sessions each storing a 50kb object could lead to a 50MB memory overhead. In other words, think carefully about size and caching before resorting to the use of the session.
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, so it’s normally nothing you’ll need to be concerned about.
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 "weblog/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
Redirecting is what actions that update the model do when they’re done. The save_post
method shouldn’t be responsible for also showing the post once it’s saved – that’s the job for show_post
. So once save_post
has completed its business, it’ll redirect to show_post
. All redirects are external, which means that when the user refreshes his browser, it’s not going to save the post again, but rather just show it one more time.
This sounds fairly simple, but the redirection is complicated by the quest for a phenomenon known as “pretty urls”. Instead of accepting the dreadful beings that is “weblog_controller?action=show&post_id=5”, Action Controller goes out of its way to represent the former as “/weblog/show/5”. And this is even the simple case. As an example of a more advanced pretty url consider “/library/books/ISBN/0743536703/show”, which can be mapped to books_controller?action=show&type=ISBN&id=0743536703.
Redirects work by rewriting the URL of the current action. So if the show action was called by “/library/books/ISBN/0743536703/show”, we can redirect to an edit action simply by doing redirect_to(:action => "edit")
, which could throw the user to “/library/books/ISBN/0743536703/edit”. Naturally, you’ll need to setup the .htaccess (or other means of URL rewriting for the web server) to point to the proper controller and action in the first place, but once you have, it can be rewritten with ease.
Let’s consider a bunch of examples on how to go from “/library/books/ISBN/0743536703/edit” to somewhere else:
redirect_to(:action => "show", :action_prefix => "XTC/123") =>
"http://www.singlefile.com/library/books/XTC/123/show"
redirect_to(:path_params => {"type" => "EXBC"}) =>
"http://www.singlefile.com/library/books/EXBC/0743536703/show"
redirect_to(:controller => "settings") =>
"http://www.singlefile.com/library/settings/"
For more examples of redirecting options, have a look at the unit test in test/controller/url_test.rb. It’s very readable and will give you an excellent understanding of the different options and what they do.
Calling multiple redirects or renders
The rule for handling calls of multiple redirects and renders is that the first call wins. So in the following example:
def do_something
redirect_to :action => "elsewhere"
render_action "overthere"
end
Only the redirect happens. The rendering call is simply ignored.
Environments
Action Controller works out of the box with CGI, FastCGI, and mod_ruby. CGI and mod_ruby controllers are triggered just the same using:
WeblogController.process_cgi
FastCGI controllers are triggered using:
FCGI.each_cgi{ |cgi| WeblogController.process_cgi(cgi) }
Constant Summary collapse
- DEFAULT_RENDER_STATUS_CODE =
"200 OK"
- DEFAULT_SEND_FILE_OPTIONS =
{ :type => 'application/octet-stream'.freeze, :disposition => 'attachment'.freeze, :stream => true, :buffer_size => 4096 }.freeze
- @@view_controller_internals =
Determines whether the view has access to controller internals @request, @response, @session, and @template. By default, it does.
true
- @@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
Instance Attribute Summary collapse
-
#assigns ⇒ Object
Holds the hash of variables that are passed on to the template class to be made available to the view.
-
#headers ⇒ Object
Holds a hash of header names and values.
-
#params ⇒ Object
Holds a hash of all the GET, POST, and Url parameters passed to the action.
-
#request ⇒ Object
Holds the request object that’s primarily used to get environment variables through access like
@request.env["REQUEST_URI"]
. -
#response ⇒ Object
Holds the response object that’s primarily used to set additional HTTP headers through access like
@response.headers["Cache-Control"] = "no-cache"
. -
#session ⇒ Object
Holds a hash of objects in the session.
Class Method Summary collapse
-
.controller_class_name ⇒ Object
Converts the class name from something like “OneModule::TwoModule::NeatController” to “NeatController”.
-
.controller_name ⇒ Object
Converts the class name from something like “OneModule::TwoModule::NeatController” to “neat”.
-
.process(request, response) ⇒ Object
Factory for the standard create, process loop where the controller is discarded after processing.
-
.process_cgi(cgi = CGI.new, session_options = {}) ⇒ Object
Process a request extracted from an CGI object and return a response.
-
.process_test(request) ⇒ Object
Process a test request called with a
TestRequest
object.
Instance Method Summary collapse
-
#action_name ⇒ Object
Returns the name of the action this controller is processing.
-
#controller_class_name ⇒ Object
Converts the class name from something like “OneModule::TwoModule::NeatController” to “NeatController”.
-
#controller_name ⇒ Object
Converts the class name from something like “OneModule::TwoModule::NeatController” to “neat”.
- #module_name ⇒ Object
-
#process(request, response, method = :perform_action, *arguments) ⇒ Object
Extracts the action_name from the request parameters and performs that action.
-
#process_cgi(cgi, session_options = {}) ⇒ Object
:nodoc:.
-
#process_test(request) ⇒ Object
:nodoc:.
-
#url_for(options = {}, *parameters_for_method_reference) ⇒ Object
Returns an URL that has been rewritten according to the hash of
options
(for doing a complete redirect, use redirect_to).
Instance Attribute Details
#assigns ⇒ Object
Holds the hash of variables that are passed on to the template class to be made available to the view. This hash is generated by taking a snapshot of all the instance variables in the current scope just before a template is rendered.
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# File 'lib/action_controller/base.rb', line 247 def assigns @assigns end |
#headers ⇒ Object
Holds a hash of header names and values. Accessed like @headers["Cache-Control"]
to get the value of the Cache-Control directive. Values should always be specified as strings.
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# File 'lib/action_controller/base.rb', line 243 def headers @headers end |
#params ⇒ Object
Holds a hash of all the GET, POST, and Url parameters passed to the action. Accessed like @params["post_id"]
to get the post_id. No type casts are made, so all values are returned as strings.
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# File 'lib/action_controller/base.rb', line 229 def params @params end |
#request ⇒ Object
Holds the request object that’s primarily used to get environment variables through access like @request.env["REQUEST_URI"]
.
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# File 'lib/action_controller/base.rb', line 225 def request @request end |
#response ⇒ Object
Holds the response object that’s primarily used to set additional HTTP headers through access like @response.headers["Cache-Control"] = "no-cache"
. Can also be used to access the final body HTML after a template has been rendered through @response.body – useful for after_filter
s that wants to manipulate the output, such as a OutputCompressionFilter.
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# File 'lib/action_controller/base.rb', line 235 def response @response end |
#session ⇒ Object
Holds a hash of objects in the session. Accessed like @session["person"]
to get the object tied to the “person” key. The session will hold any type of object as values, but the key should be a string.
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# File 'lib/action_controller/base.rb', line 239 def session @session end |
Class Method Details
.controller_class_name ⇒ Object
Converts the class name from something like “OneModule::TwoModule::NeatController” to “NeatController”.
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# File 'lib/action_controller/base.rb', line 256 def controller_class_name Inflector.demodulize(name) end |
.controller_name ⇒ Object
Converts the class name from something like “OneModule::TwoModule::NeatController” to “neat”.
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# File 'lib/action_controller/base.rb', line 261 def controller_name Inflector.underscore(controller_class_name.sub(/Controller/, "")) 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 251 def process(request, response) #:nodoc: new.process(request, response) end |
.process_cgi(cgi = CGI.new, session_options = {}) ⇒ Object
Process a request extracted from an 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 thesession_key
parameter of the request, 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 thesession_id
option is not set, an ArgumentError is raised. -
:session_expires
- the time the current session expires, as aTime
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
- iftrue
, this session will only work over HTTPS. -
:session_path
- the path for which this session applies. Defaults to the directory of the CGI script.
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# File 'lib/action_controller/cgi_process.rb', line 28 def self.process_cgi(cgi = CGI.new, = {}) new.process_cgi(cgi, ) 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 23 def self.process_test(request) new.process_test(request) end |
Instance Method Details
#action_name ⇒ Object
Returns the name of the action this controller is processing.
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# File 'lib/action_controller/base.rb', line 355 def action_name @params["action"] || "index" end |
#controller_class_name ⇒ Object
Converts the class name from something like “OneModule::TwoModule::NeatController” to “NeatController”.
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# File 'lib/action_controller/base.rb', line 345 def controller_class_name self.class.controller_class_name end |
#controller_name ⇒ Object
Converts the class name from something like “OneModule::TwoModule::NeatController” to “neat”.
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# File 'lib/action_controller/base.rb', line 350 def controller_name self.class.controller_name end |
#module_name ⇒ Object
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# File 'lib/action_controller/base.rb', line 340 def module_name @params["module"] 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 268 def process(request, response, method = :perform_action, *arguments) #:nodoc: initialize_template_class(response) assign_shortcuts(request, response) initialize_current_url log_processing unless logger.nil? send(method, *arguments) close_session return @response end |
#process_cgi(cgi, session_options = {}) ⇒ Object
:nodoc:
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# File 'lib/action_controller/cgi_process.rb', line 32 def process_cgi(cgi, = {}) #:nodoc: process(CgiRequest.new(cgi, ), CgiResponse.new(cgi)).out end |
#process_test(request) ⇒ Object
:nodoc:
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# File 'lib/action_controller/test_process.rb', line 27 def process_test(request) #:nodoc: process(request, TestResponse.new) end |
#url_for(options = {}, *parameters_for_method_reference) ⇒ Object
Returns an URL that has been rewritten according to the hash of options
(for doing a complete redirect, use redirect_to). The valid keys in options are specified below with an example going from “/library/books/ISBN/0743536703/show” (mapped to books_controller?action=show&type=ISBN&id=0743536703):
.---> controller .--> action
/library/books/ISBN/0743536703/show
'------> '--------------> action_prefix
controller_prefix (or module)
-
:controller_prefix
- specifies the string before the controller name, which would be “/library” for the example. Called with “/shop” gives “/shop/books/ISBN/0743536703/show”. -
:module
- serves as a alias to :controller_prefix (overwrites :controller_prefix unless its nil) -
:controller
- specifies a new controller and clears out everything after the controller name (including the action, the pre- and suffix, and all params), so called with “settings” gives “/library/settings/”. -
:action_prefix
- specifies the string between the controller name and the action name, which would be “/ISBN/0743536703” for the example. Called with “/XTC/123/” gives “/library/books/XTC/123/show”. -
:action
- specifies a new action, so called with “edit” gives “/library/books/ISBN/0743536703/edit” -
:action_suffix
- specifies the string after the action name, which would be empty for the example. Called with “/detailed” gives “/library/books/ISBN/0743536703/detailed”. -
:path_params
- specifies a hash that contains keys mapping to the request parameter names. In the example, { “type” => “ISBN”, “id” => “0743536703” } would be the path_params. It serves as another way of replacing part of the action_prefix or action_suffix. So passing { “type” => “XTC” } would give “/library/books/XTC/0743536703/show”. -
:id
- shortcut where “:id => 5” can be used instead of specifying :path_params => { “id” => 5 }. Called with “123” gives “/library/books/ISBN/123/show”. -
:params
- specifies a hash that represents the regular request parameters, such as { “cat” => 1, “origin” => “there”} that would give “?cat=1&origin=there”. Called with { “temporary” => 1 } in the example would give “/library/books/ISBN/0743536703/show?temporary=1” -
:anchor
- specifies the anchor name to be appended to the path. Called with “x14” would give “/library/books/ISBN/0743536703/show#x14” -
:only_path
- if true, returns the absolute URL (omitting the protocol, host name, and port).
Naturally, you can combine multiple options in a single redirect. Examples:
redirect_to(:controller_prefix => "/shop", :controller => "settings")
redirect_to(:controller_prefix => false, :controller => "settings") # breaks out of the current controller_prefix
redirect_to(:action => "edit", :id => 3425)
redirect_to(:action => "edit", :path_params => { "type" => "XTC" }, :params => { "temp" => 1})
redirect_to(:action => "publish", :action_prefix => "/published", :anchor => "x14")
Instead of passing an options hash, you can also pass a method reference in the form of a symbol. Consider this example:
class WeblogController < ActionController::Base
def update
# do some update
redirect_to :dashboard_url
end
protected
def dashboard_url
url_for :controller => (@project.active? ? "project" : "account"), :action => "dashboard"
end
end
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# File 'lib/action_controller/base.rb', line 332 def url_for( = {}, *parameters_for_method_reference) #:doc: case when String then when Symbol then send(, *parameters_for_method_reference) when Hash then @url.rewrite(()) end end |