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<div id="classHeader">
<table class="header-table">
<tr class="top-aligned-row">
<td><strong>Class</strong></td>
<td class="class-name-in-header">ActionController::Base</td>
</tr>
<tr class="top-aligned-row">
<td><strong>In:</strong></td>
<td>
<a href="../../files/lib/action_controller/base_rb.html">
lib/action_controller/base.rb
</a>
<br />
</td>
</tr>
<tr class="top-aligned-row">
<td><strong>Parent:</strong></td>
<td>
<a href="../Object.html">
Object
</a>
</td>
</tr>
</table>
</div>
<!-- banner header -->
<div id="bodyContent">
<div id="contextContent">
<div id="description">
<p>
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 <a
href="Base.html#M000303">render</a> 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.
</p>
<p>
A sample controller could look like this:
</p>
<pre>
class GuestBookController < ActionController::Base
def index
@entries = Entry.find(:all)
end
def sign
Entry.create(params[:entry])
redirect_to :action => "index"
end
end
</pre>
<p>
Actions, by default, <a href="Base.html#M000303">render</a> a template in
the <tt>app/views</tt> directory corresponding to the name of the
controller and action after executing code in the action. For example, the
<tt>index</tt> action of the GuestBookController would <a
href="Base.html#M000303">render</a> the template
<tt>app/views/guestbook/index.erb</tt> by default after populating the
<tt>@entries</tt> instance variable.
</p>
<p>
Unlike index, the sign action will not <a
href="Base.html#M000303">render</a> 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.
</p>
<p>
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.
</p>
<h2>Requests</h2>
<p>
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.
</p>
<p>
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:
</p>
<pre>
def server_ip
location = request.env["SERVER_ADDR"]
render :text => "This server hosted at #{location}"
end
</pre>
<h2>Parameters</h2>
<p>
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
<tt>/weblog/list?category=All&limit=5</tt> will include <tt>{
"category" => "All", "limit" => 5
}</tt> in params.
</p>
<p>
It‘s also possible to construct multi-dimensional parameter hashes by
specifying keys using brackets, such as:
</p>
<pre>
<input type="text" name="post[name]" value="david">
<input type="text" name="post[address]" value="hyacintvej">
</pre>
<p>
A request stemming from a form holding these inputs will include <tt>{
"post" => { "name" => "david",
"address" => "hyacintvej" } }</tt>. If the address
input had been named "post[address][street]", the params would
have included <tt>{ "post" => { "address" => {
"street" => "hyacintvej" } } }</tt>. There‘s
no limit to the depth of the nesting.
</p>
<h2>Sessions</h2>
<p>
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.
</p>
<p>
You can place objects in the session by using the <tt>session</tt> method,
which accesses a hash:
</p>
<pre>
session[:person] = Person.authenticate(user_name, password)
</pre>
<p>
And retrieved again through the same hash:
</p>
<pre>
Hello #{session[:person]}
</pre>
<p>
For removing objects from the session, you can either assign a single key
to <tt>nil</tt>:
</p>
<pre>
# removes :person from session
session[:person] = nil
</pre>
<p>
or you can remove the entire session with <tt><a
href="Base.html#M000313">reset_session</a></tt>.
</p>
<p>
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.
</p>
<p>
Do not put secret information in cookie-based sessions!
</p>
<p>
Other options for session storage are:
</p>
<ul>
<li>ActiveRecord::SessionStore - 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
ActiveRecord::SessionStore, set
<pre>
config.action_controller.session_store = :active_record_store
</pre>
<p>
in your <tt>config/environment.rb</tt> and run <tt>rake
db:sessions:create</tt>.
</p>
</li>
<li>MemCacheStore - Sessions are stored as entries in your memcached cache. Set
the session store type in <tt>config/environment.rb</tt>:
<pre>
config.action_controller.session_store = :mem_cache_store
</pre>
<p>
This assumes that memcached has been installed and configured properly. See
the MemCacheStore docs for more information.
</p>
</li>
</ul>
<h2>Responses</h2>
<p>
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.
</p>
<h2>Renders</h2>
<p>
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:
</p>
<pre>
def show
@post = Post.find(params[:id])
end
</pre>
<p>
Which are then automatically available to the view:
</p>
<pre>
Title: <%= @post.title %>
</pre>
<p>
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:
</p>
<pre>
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
</pre>
<p>
Read more about writing ERb and Builder templates in <a
href="../ActionView/Base.html">classes/ActionView/Base.html</a>.
</p>
<h2>Redirects</h2>
<p>
Redirects are used to move from one action to another. For example, after a
<tt>create</tt> 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 <tt>show</tt> action that we‘ll assume has already
been created. The code might look like this:
</p>
<pre>
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
</pre>
<p>
In this case, after saving our new entry to the database, the user is
redirected to the <tt>show</tt> method which is then executed.
</p>
<h2>Calling multiple redirects or renders</h2>
<p>
An action may contain only a single <a href="Base.html#M000303">render</a>
or a single redirect. Attempting to try to do either again will result in a
DoubleRenderError:
</p>
<pre>
def do_something
redirect_to :action => "elsewhere"
render :action => "overthere" # raises DoubleRenderError
end
</pre>
<p>
If you need to redirect on the condition of something, then be sure to add
"and return" to halt execution.
</p>
<pre>
def do_something
redirect_to(:action => "elsewhere") and return if monkeys.nil?
render :action => "overthere" # won't be called if monkeys is nil
end
</pre>
</div>
</div>
<div id="method-list">
<h3 class="section-bar">Methods</h3>
<div class="name-list">
<a href="#M000291">append_view_path</a>
<a href="#M000302">append_view_path</a>
<a href="#M000282">call</a>
<a href="#M000295">controller_class_name</a>
<a href="#M000283">controller_class_name</a>
<a href="#M000284">controller_name</a>
<a href="#M000296">controller_name</a>
<a href="#M000285">controller_path</a>
<a href="#M000297">controller_path</a>
<a href="#M000306">default_url_options</a>
<a href="#M000311">expires_in</a>
<a href="#M000312">expires_now</a>
<a href="#M000292">filter_parameter_logging</a>
<a href="#M000310">fresh_when</a>
<a href="#M000305">head</a>
<a href="#M000286">hidden_actions</a>
<a href="#M000287">hide_action</a>
<a href="#M000290">prepend_view_path</a>
<a href="#M000301">prepend_view_path</a>
<a href="#M000307">redirect_to</a>
<a href="#M000308">redirect_to_full_url</a>
<a href="#M000303">render</a>
<a href="#M000304">render_to_string</a>
<a href="#M000313">reset_session</a>
<a href="#M000293">send_response</a>
<a href="#M000298">session_enabled?</a>
<a href="#M000309">stale?</a>
<a href="#M000294">url_for</a>
<a href="#M000299">view_paths</a>
<a href="#M000288">view_paths</a>
<a href="#M000289">view_paths=</a>
<a href="#M000300">view_paths=</a>
</div>
</div>
</div>
<!-- if includes -->
<div id="includes">
<h3 class="section-bar">Included Modules</h3>
<div id="includes-list">
<span class="include-name">StatusCodes</span>
</div>
</div>
<div id="section">
<div id="constants-list">
<h3 class="section-bar">Constants</h3>
<div class="name-list">
<table summary="Constants">
<tr class="top-aligned-row context-row">
<td class="context-item-name">DEFAULT_RENDER_STATUS_CODE</td>
<td>=</td>
<td class="context-item-value">"200 OK"</td>
</tr>
</table>
</div>
</div>
<div id="attribute-list">
<h3 class="section-bar">Attributes</h3>
<div class="name-list">
<table>
<tr class="top-aligned-row context-row">
<td class="context-item-name">action_name</td>
<td class="context-item-value"> [RW] </td>
<td class="context-item-desc">
Returns the name of the action this controller is processing.
</td>
</tr>
</table>
</div>
</div>
<!-- if method_list -->
<div id="methods">
<h3 class="section-bar">Public Class methods</h3>
<div id="method-M000291" class="method-detail">
<a name="M000291"></a>
<div class="method-heading">
<a href="Base.src/M000291.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000291.html');return false;">
<span class="method-name">append_view_path</span><span class="method-args">(path)</span>
</a>
</div>
<div class="method-description">
<p>
Adds a view_path to the end of the <a
href="Base.html#M000288">view_paths</a> array. If the current class has no
view paths, copy them from the superclass. This change will be visible for
all future requests.
</p>
<pre>
ArticleController.append_view_path("views/default")
ArticleController.append_view_path(["views/default", "views/custom"])
</pre>
</div>
</div>
<div id="method-M000282" class="method-detail">
<a name="M000282"></a>
<div class="method-heading">
<a href="Base.src/M000282.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000282.html');return false;">
<span class="method-name">call</span><span class="method-args">(env)</span>
</a>
</div>
<div class="method-description">
</div>
</div>
<div id="method-M000283" class="method-detail">
<a name="M000283"></a>
<div class="method-heading">
<a href="Base.src/M000283.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000283.html');return false;">
<span class="method-name">controller_class_name</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Converts the class name from something like
"OneModule::TwoModule::NeatController" to
"NeatController".
</p>
</div>
</div>
<div id="method-M000284" class="method-detail">
<a name="M000284"></a>
<div class="method-heading">
<a href="Base.src/M000284.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000284.html');return false;">
<span class="method-name">controller_name</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Converts the class name from something like
"OneModule::TwoModule::NeatController" to "neat".
</p>
</div>
</div>
<div id="method-M000285" class="method-detail">
<a name="M000285"></a>
<div class="method-heading">
<a href="Base.src/M000285.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000285.html');return false;">
<span class="method-name">controller_path</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Converts the class name from something like
"OneModule::TwoModule::NeatController" to
"one_module/two_module/neat".
</p>
</div>
</div>
<div id="method-M000292" class="method-detail">
<a name="M000292"></a>
<div class="method-heading">
<a href="Base.src/M000292.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000292.html');return false;">
<span class="method-name">filter_parameter_logging</span><span class="method-args">(*filter_words) {|key, value| ...}</span>
</a>
</div>
<div class="method-description">
<p>
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.
</p>
<p>
Examples:
</p>
<pre>
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]"
</pre>
</div>
</div>
<div id="method-M000286" class="method-detail">
<a name="M000286"></a>
<div class="method-heading">
<a href="Base.src/M000286.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000286.html');return false;">
<span class="method-name">hidden_actions</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Return an array containing the names of public methods that have been
marked hidden from the action processor. By default, all methods defined in
<a href="Base.html">ActionController::Base</a> and included modules are
hidden. More methods can be hidden using <tt>hide_actions</tt>.
</p>
</div>
</div>
<div id="method-M000287" class="method-detail">
<a name="M000287"></a>
<div class="method-heading">
<a href="Base.src/M000287.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000287.html');return false;">
<span class="method-name">hide_action</span><span class="method-args">(*names)</span>
</a>
</div>
<div class="method-description">
<p>
Hide each of the given methods from being callable as actions.
</p>
</div>
</div>
<div id="method-M000290" class="method-detail">
<a name="M000290"></a>
<div class="method-heading">
<a href="Base.src/M000290.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000290.html');return false;">
<span class="method-name">prepend_view_path</span><span class="method-args">(path)</span>
</a>
</div>
<div class="method-description">
<p>
Adds a view_path to the front of the <a
href="Base.html#M000288">view_paths</a> array. If the current class has no
view paths, copy them from the superclass. This change will be visible for
all future requests.
</p>
<pre>
ArticleController.prepend_view_path("views/default")
ArticleController.prepend_view_path(["views/default", "views/custom"])
</pre>
</div>
</div>
<div id="method-M000288" class="method-detail">
<a name="M000288"></a>
<div class="method-heading">
<a href="Base.src/M000288.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000288.html');return false;">
<span class="method-name">view_paths</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
View load paths determine the bases from which template references can be
made. So a <a href="Base.html#M000282">call</a> to <a
href="Base.html#M000303">render</a>("test/template") will be
looked up in the view load paths array and the closest match will be
returned.
</p>
</div>
</div>
<div id="method-M000289" class="method-detail">
<a name="M000289"></a>
<div class="method-heading">
<a href="Base.src/M000289.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000289.html');return false;">
<span class="method-name">view_paths=</span><span class="method-args">(value)</span>
</a>
</div>
<div class="method-description">
</div>
</div>
<h3 class="section-bar">Public Instance methods</h3>
<div id="method-M000302" class="method-detail">
<a name="M000302"></a>
<div class="method-heading">
<a href="Base.src/M000302.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000302.html');return false;">
<span class="method-name">append_view_path</span><span class="method-args">(path)</span>
</a>
</div>
<div class="method-description">
<p>
Adds a view_path to the end of the <a
href="Base.html#M000288">view_paths</a> array. This change affects the
current request only.
</p>
<pre>
self.append_view_path("views/default")
self.append_view_path(["views/default", "views/custom"])
</pre>
</div>
</div>
<div id="method-M000295" class="method-detail">
<a name="M000295"></a>
<div class="method-heading">
<a href="Base.src/M000295.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000295.html');return false;">
<span class="method-name">controller_class_name</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Converts the class name from something like
"OneModule::TwoModule::NeatController" to
"NeatController".
</p>
</div>
</div>
<div id="method-M000296" class="method-detail">
<a name="M000296"></a>
<div class="method-heading">
<a href="Base.src/M000296.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000296.html');return false;">
<span class="method-name">controller_name</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Converts the class name from something like
"OneModule::TwoModule::NeatController" to "neat".
</p>
</div>
</div>
<div id="method-M000297" class="method-detail">
<a name="M000297"></a>
<div class="method-heading">
<a href="Base.src/M000297.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000297.html');return false;">
<span class="method-name">controller_path</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
Converts the class name from something like
"OneModule::TwoModule::NeatController" to
"one_module/two_module/neat".
</p>
</div>
</div>
<div id="method-M000301" class="method-detail">
<a name="M000301"></a>
<div class="method-heading">
<a href="Base.src/M000301.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000301.html');return false;">
<span class="method-name">prepend_view_path</span><span class="method-args">(path)</span>
</a>
</div>
<div class="method-description">
<p>
Adds a view_path to the front of the <a
href="Base.html#M000288">view_paths</a> array. This change affects the
current request only.
</p>
<pre>
self.prepend_view_path("views/default")
self.prepend_view_path(["views/default", "views/custom"])
</pre>
</div>
</div>
<div id="method-M000293" class="method-detail">
<a name="M000293"></a>
<div class="method-heading">
<a href="Base.src/M000293.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000293.html');return false;">
<span class="method-name">send_response</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
</div>
</div>
<div id="method-M000298" class="method-detail">
<a name="M000298"></a>
<div class="method-heading">
<a href="Base.src/M000298.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000298.html');return false;">
<span class="method-name">session_enabled?</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
</div>
</div>
<div id="method-M000294" class="method-detail">
<a name="M000294"></a>
<div class="method-heading">
<a href="Base.src/M000294.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000294.html');return false;">
<span class="method-name">url_for</span><span class="method-args">(options = {})</span>
</a>
</div>
<div class="method-description">
<p>
Returns a URL that has been rewritten according to the options hash and the
defined routes. (For doing a complete redirect, use <tt><a
href="Base.html#M000307">redirect_to</a></tt>).
</p>
<p>
<tt><a href="Base.html#M000294">url_for</a></tt> is used to:
</p>
<p>
All keys given to <tt><a href="Base.html#M000294">url_for</a></tt> are
forwarded to the Route module, save for the following:
</p>
<ul>
<li><tt>:anchor</tt> - Specifies the anchor name to be appended to the path.
For example, <tt><a href="Base.html#M000294">url_for</a> :controller =>
‘posts’, :action => ‘show’, :id => 10,
:anchor => ‘comments‘</tt> will produce
"/posts/show/10#comments".
</li>
<li><tt>:only_path</tt> - If true, returns the relative URL (omitting the
protocol, host name, and port) (<tt>false</tt> by default).
</li>
<li><tt>:trailing_slash</tt> - If true, adds a trailing slash, as in
"/archive/2005/". Note that this is currently not recommended
since it breaks caching.
</li>
<li><tt>:host</tt> - Overrides the default (current) host if provided.
</li>
<li><tt>:protocol</tt> - Overrides the default (current) protocol if provided.
</li>
<li><tt>:port</tt> - Optionally specify the port to connect to.
</li>
<li><tt>:user</tt> - Inline HTTP authentication (only plucked out if
<tt>:password</tt> is also present).
</li>
<li><tt>:password</tt> - Inline HTTP authentication (only plucked out if
<tt>:user</tt> is also present).
</li>
<li><tt>:skip_relative_url_root</tt> - If true, the url is not constructed
using the <tt>relative_url_root</tt> of the request so the path will
include the web server relative installation directory.
</li>
</ul>
<p>
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>.
</p>
<p>
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 <a href="Base.html#M000294">url_for</a> statements and their
corresponding URLs:
</p>
<pre>
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:123@host.com/posts'
</pre>
<p>
When generating a new URL, missing values may be filled in from the current
request‘s parameters. For example, <tt><a
href="Base.html#M000294">url_for</a> :action =>
‘some_action‘</tt> will retain the current controller, as
expected. This behavior extends to other parameters, including
<tt>:controller</tt>, <tt>:id</tt>, and any other parameters that are
placed into a Route‘s path. The URL helpers such as <tt><a
href="Base.html#M000294">url_for</a></tt> 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:
</p>
<ul>
<li>If the controller name begins with a slash no defaults are used:
<pre>
url_for :controller => '/home'
</pre>
<p>
In particular, a leading slash ensures no namespace is assumed. Thus, while
<tt><a href="Base.html#M000294">url_for</a> :controller =>
‘users‘</tt> may resolve to <tt>Admin::UsersController</tt> if
the current controller lives under that module, <tt><a
href="Base.html#M000294">url_for</a> :controller =>
’/users‘</tt> ensures you link to <tt>::UsersController</tt> no
matter what.
</p>
</li>
<li>If the controller changes, the action will default to index unless provided
</li>
</ul>
<p>
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
<tt>map.connect ‘people/:last/:first/:action’, :action =>
‘bio’, :controller => ‘people‘</tt>.
</p>
<p>
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.
</p>
<ul>
<li><tt><a href="Base.html#M000294">url_for</a> :action =>
‘bio‘</tt> — During the generation of this URL, default
values will be used for the first and
</li>
</ul>
<p>
last components, and the action shall change. The generated URL will be,
"people/hh/david/bio".
</p>
<ul>
<li><tt><a href="Base.html#M000294">url_for</a> :first =>
‘davids-little-brother‘</tt> This generates the URL
‘people/hh/davids-little-brother’ — note that this URL
leaves out the assumed action of ‘bio’.
</li>
</ul>
<p>
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
<tt>:first</tt> is not equal to default value for <tt>:first</tt> 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 <tt>:name => nil</tt> to <tt><a
href="Base.html#M000294">url_for</a></tt>‘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:
</p>
<pre>
url_for :controller => 'posts', :action => nil
</pre>
<p>
If you explicitly want to create a URL that‘s almost the same as the
current URL, you can do so using the <tt>:overwrite_params</tt> 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
</p>
<pre>
url_for :overwrite_params => { :action => 'print' }
</pre>
<p>
This takes the current URL as is and only exchanges the action. In
contrast, <tt><a href="Base.html#M000294">url_for</a> :action =>
‘print‘</tt> would have slashed-off the path components after
the changed action.
</p>
</div>
</div>
<div id="method-M000299" class="method-detail">
<a name="M000299"></a>
<div class="method-heading">
<a href="Base.src/M000299.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000299.html');return false;">
<span class="method-name">view_paths</span><span class="method-args">()</span>
</a>
</div>
<div class="method-description">
<p>
View load paths for controller.
</p>
</div>
</div>
<div id="method-M000300" class="method-detail">
<a name="M000300"></a>
<div class="method-heading">
<a href="Base.src/M000300.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000300.html');return false;">
<span class="method-name">view_paths=</span><span class="method-args">(value)</span>
</a>
</div>
<div class="method-description">
</div>
</div>
<h3 class="section-bar">Protected Instance methods</h3>
<div id="method-M000306" class="method-detail">
<a name="M000306"></a>
<div class="method-heading">
<a href="Base.src/M000306.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000306.html');return false;">
<span class="method-name">default_url_options</span><span class="method-args">(options = nil)</span>
</a>
</div>
<div class="method-description">
<p>
Overwrite to implement a number of default options that all <a
href="Base.html#M000294">url_for</a>-based methods will use. The default
options should come in the form of a hash, just like the one you would use
for <a href="Base.html#M000294">url_for</a> directly. Example:
</p>
<pre>
def default_url_options(options)
{ :project => @project.active? ? @project.url_name : "unknown" }
end
</pre>
<p>
As you can infer from the example, this is mostly useful for situations
where you want to centralize dynamic decisions about the urls as they stem
from the business domain. Please note that any individual <a
href="Base.html#M000294">url_for</a> <a href="Base.html#M000282">call</a>
can always override the defaults set by this method.
</p>
</div>
</div>
<div id="method-M000311" class="method-detail">
<a name="M000311"></a>
<div class="method-heading">
<a href="Base.src/M000311.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000311.html');return false;">
<span class="method-name">expires_in</span><span class="method-args">(seconds, options = {})</span>
</a>
</div>
<div class="method-description">
<p>
Sets a HTTP 1.1 Cache-Control header. Defaults to issuing a
"private" instruction, so that intermediate caches
shouldn‘t cache the response.
</p>
<p>
Examples:
</p>
<pre>
expires_in 20.minutes
expires_in 3.hours, :public => true
expires in 3.hours, 'max-stale' => 5.hours, :public => true
</pre>
<p>
This method will overwrite an existing Cache-Control header. See <a
href="http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html">www.w3.org/Protocols/rfc2616/rfc2616-sec14.html</a>
for more possibilities.
</p>
</div>
</div>
<div id="method-M000312" class="method-detail">
<a name="M000312"></a>
<div class="method-heading">
<a href="Base.src/M000312.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000312.html');return false;">
<span class="method-name">expires_now</span><span class="method-args">(</span>
</a>
</div>
<div class="method-description">
<p>
Sets a HTTP 1.1 Cache-Control header of "no-cache" so no caching
should occur by the browser or intermediate caches (like caching proxy
servers).
</p>
</div>
</div>
<div id="method-M000310" class="method-detail">
<a name="M000310"></a>
<div class="method-heading">
<a href="Base.src/M000310.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000310.html');return false;">
<span class="method-name">fresh_when</span><span class="method-args">(options)</span>
</a>
</div>
<div class="method-description">
<p>
Sets the etag, last_modified, or both on the response and renders a
"304 Not Modified" response if the request is already fresh.
</p>
<p>
Parameters:
</p>
<ul>
<li><tt>:etag</tt>
</li>
<li><tt>:last_modified</tt>
</li>
<li><tt>:public</tt> By default the Cache-Control header is private, set this
to true if you want your application to be cachable by other devices (proxy
caches).
</li>
</ul>
<p>
Example:
</p>
<pre>
def show
@article = Article.find(params[:id])
fresh_when(:etag => @article, :last_modified => @article.created_at.utc, :public => true)
end
</pre>
<p>
This will <a href="Base.html#M000303">render</a> the show template if the
request isn‘t sending a matching etag or If-Modified-Since header and
just a "304 Not Modified" response if there‘s a match.
</p>
</div>
</div>
<div id="method-M000305" class="method-detail">
<a name="M000305"></a>
<div class="method-heading">
<a href="Base.src/M000305.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000305.html');return false;">
<span class="method-name">head</span><span class="method-args">(*args)</span>
</a>
</div>
<div class="method-description">
<p>
Return a response that has no content (merely headers). The options
argument is interpreted to be a hash of header names and values. This
allows you to easily return a response that consists only of significant
headers:
</p>
<pre>
head :created, :location => person_path(@person)
</pre>
<p>
It can also be used to return exceptional conditions:
</p>
<pre>
return head(:method_not_allowed) unless request.post?
return head(:bad_request) unless valid_request?
render
</pre>
</div>
</div>
<div id="method-M000307" class="method-detail">
<a name="M000307"></a>
<div class="method-heading">
<a href="Base.src/M000307.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000307.html');return false;">
<span class="method-name">redirect_to</span><span class="method-args">(options = {}, response_status = {})</span>
</a>
</div>
<div class="method-description">
<p>
Redirects the browser to the target specified in <tt>options</tt>. This
parameter can take one of three forms:
</p>
<ul>
<li><tt>Hash</tt> - The URL will be generated by calling <a
href="Base.html#M000294">url_for</a> with the <tt>options</tt>.
</li>
<li><tt>Record</tt> - The URL will be generated by calling <a
href="Base.html#M000294">url_for</a> with the <tt>options</tt>, which will
reference a named URL for that record.
</li>
<li><tt>String</tt> starting with <tt>protocol://</tt> (like <tt>http://</tt>)
- Is passed straight through as the target for redirection.
</li>
<li><tt>String</tt> not containing a protocol - The current protocol and host
is prepended to the string.
</li>
<li><tt>:back</tt> - Back to the page that issued the request. Useful for forms
that are triggered from multiple places. Short-hand for <tt><a
href="Base.html#M000307">redirect_to</a>(request.env["HTTP_REFERER"])</tt>
</li>
</ul>
<p>
Examples:
</p>
<pre>
redirect_to :action => "show", :id => 5
redirect_to post
redirect_to "http://www.rubyonrails.org"
redirect_to "/images/screenshot.jpg"
redirect_to articles_url
redirect_to :back
</pre>
<p>
The redirection happens as a "302 Moved" header unless otherwise
specified.
</p>
<p>
Examples:
</p>
<pre>
redirect_to post_url(@post), :status=>:found
redirect_to :action=>'atom', :status=>:moved_permanently
redirect_to post_url(@post), :status=>301
redirect_to :action=>'atom', :status=>302
</pre>
<p>
When using <tt><a href="Base.html#M000307">redirect_to</a> :back</tt>, if
there is no referrer, RedirectBackError will be raised. You may specify
some fallback behavior for this case by rescuing RedirectBackError.
</p>
</div>
</div>
<div id="method-M000308" class="method-detail">
<a name="M000308"></a>
<div class="method-heading">
<a href="Base.src/M000308.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000308.html');return false;">
<span class="method-name">redirect_to_full_url</span><span class="method-args">(url, status)</span>
</a>
</div>
<div class="method-description">
</div>
</div>
<div id="method-M000303" class="method-detail">
<a name="M000303"></a>
<div class="method-heading">
<a href="Base.src/M000303.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000303.html');return false;">
<span class="method-name">render</span><span class="method-args">(options = nil, extra_options = {}, &block)</span>
</a>
</div>
<div class="method-description">
<p>
Renders the content that will be returned to the browser as the response
body.
</p>
<h3>Rendering an action</h3>
<p>
Action rendering is the most common form and the type used automatically by
Action Controller when nothing else is specified. By default, actions are
rendered within the current layout (if one exists).
</p>
<pre>
# Renders the template for the action "goal" within the current controller
render :action => "goal"
# Renders the template for the action "short_goal" within the current controller,
# but without the current active layout
render :action => "short_goal", :layout => false
# Renders the template for the action "long_goal" within the current controller,
# but with a custom layout
render :action => "long_goal", :layout => "spectacular"
</pre>
<h3>Rendering partials</h3>
<p>
Partial rendering in a controller is most commonly used together with Ajax
calls that only update one or a few elements on a page without reloading.
Rendering of partials from the controller makes it possible to use the same
partial template in both the full-page rendering (by calling it from within
the template) and when sub-page updates happen (from the controller action
responding to Ajax calls). By default, the current layout is not used.
</p>
<pre>
# Renders the same partial with a local variable.
render :partial => "person", :locals => { :name => "david" }
# Renders the partial, making @new_person available through
# the local variable 'person'
render :partial => "person", :object => @new_person
# Renders a collection of the same partial by making each element
# of @winners available through the local variable "person" as it
# builds the complete response.
render :partial => "person", :collection => @winners
# Renders a collection of partials but with a custom local variable name
render :partial => "admin_person", :collection => @winners, :as => :person
# Renders the same collection of partials, but also renders the
# person_divider partial between each person partial.
render :partial => "person", :collection => @winners, :spacer_template => "person_divider"
# Renders a collection of partials located in a view subfolder
# outside of our current controller. In this example we will be
# rendering app/views/shared/_note.r(html|xml) Inside the partial
# each element of @new_notes is available as the local var "note".
render :partial => "shared/note", :collection => @new_notes
# Renders the partial with a status code of 500 (internal error).
render :partial => "broken", :status => 500
</pre>
<p>
Note that the partial filename must also be a valid Ruby variable name, so
e.g. 2005 and register-user are invalid.
</p>
<h2>Automatic etagging</h2>
<p>
Rendering will automatically insert the etag header on 200 OK responses.
The etag is calculated using MD5 of the response body. If a request comes
in that has a matching etag, the response will be changed to a 304 Not
Modified and the response body will be set to an empty string. No etag
header will be inserted if it‘s already set.
</p>
<h3>Rendering a template</h3>
<p>
Template rendering works just like action rendering except that it takes a
path relative to the template root. The current layout is automatically
applied.
</p>
<pre>
# Renders the template located in [TEMPLATE_ROOT]/weblog/show.r(html|xml) (in Rails, app/views/weblog/show.erb)
render :template => "weblog/show"
# Renders the template with a local variable
render :template => "weblog/show", :locals => {:customer => Customer.new}
</pre>
<h3>Rendering a file</h3>
<p>
File rendering works just like action rendering except that it takes a
filesystem path. By default, the path is assumed to be absolute, and the
current layout is not applied.
</p>
<pre>
# Renders the template located at the absolute filesystem path
render :file => "/path/to/some/template.erb"
render :file => "c:/path/to/some/template.erb"
# Renders a template within the current layout, and with a 404 status code
render :file => "/path/to/some/template.erb", :layout => true, :status => 404
render :file => "c:/path/to/some/template.erb", :layout => true, :status => 404
</pre>
<h3>Rendering text</h3>
<p>
Rendering of text is usually used for tests or for rendering prepared
content, such as a cache. By default, text rendering is not done within the
active layout.
</p>
<pre>
# Renders the clear text "hello world" with status code 200
render :text => "hello world!"
# Renders the clear text "Explosion!" with status code 500
render :text => "Explosion!", :status => 500
# Renders the clear text "Hi there!" within the current active layout (if one exists)
render :text => "Hi there!", :layout => true
# Renders the clear text "Hi there!" within the layout
# placed in "app/views/layouts/special.r(html|xml)"
render :text => "Hi there!", :layout => "special"
</pre>
<h3><a href="Streaming.html">Streaming</a> data and/or controlling the page generation</h3>
<p>
The <tt>:text</tt> option can also accept a Proc object, which can be used
to:
</p>
<ol>
<li>stream on-the-fly generated data to the browser. Note that you should use
the methods provided by ActionController::Steaming instead if you want to
stream a buffer or a file.
</li>
<li>manually control the page generation. This should generally be avoided, as
it violates the separation between code and content, and because almost
everything that can be done with this method can also be done more cleanly
using one of the other rendering methods, most notably templates.
</li>
</ol>
<p>
Two arguments are passed to the proc, a <tt>response</tt> object and an
<tt>output</tt> object. The response object is equivalent to the return
value of the ActionController::Base#response method, and can be used to
control various things in the HTTP response, such as setting the
Content-Type header. The output object is an writable <tt>IO</tt>-like
object, so one can <a href="Base.html#M000282">call</a> <tt>write</tt> and
<tt>flush</tt> on it.
</p>
<p>
The following example demonstrates how one can stream a large amount of
on-the-fly generated data to the browser:
</p>
<pre>
# Streams about 180 MB of generated data to the browser.
render :text => proc { |response, output|
10_000_000.times do |i|
output.write("This is line #{i}\n")
end
}
</pre>
<p>
Another example:
</p>
<pre>
# Renders "Hello from code!"
render :text => proc { |response, output| output.write("Hello from code!") }
</pre>
<h3>Rendering XML</h3>
<p>
Rendering XML sets the content type to application/xml.
</p>
<pre>
# Renders '<name>David</name>'
render :xml => {:name => "David"}.to_xml
</pre>
<p>
It‘s not necessary to <a href="Base.html#M000282">call</a>
<tt>to_xml</tt> on the object you want to <a
href="Base.html#M000303">render</a>, since <tt><a
href="Base.html#M000303">render</a></tt> will automatically do that for
you:
</p>
<pre>
# Also renders '<name>David</name>'
render :xml => {:name => "David"}
</pre>
<h3>Rendering JSON</h3>
<p>
Rendering JSON sets the content type to application/json and optionally
wraps the JSON in a callback. It is expected that the response will be
parsed (or eval‘d) for use as a data structure.
</p>
<pre>
# Renders '{"name": "David"}'
render :json => {:name => "David"}.to_json
</pre>
<p>
It‘s not necessary to <a href="Base.html#M000282">call</a>
<tt>to_json</tt> on the object you want to <a
href="Base.html#M000303">render</a>, since <tt><a
href="Base.html#M000303">render</a></tt> will automatically do that for
you:
</p>
<pre>
# Also renders '{"name": "David"}'
render :json => {:name => "David"}
</pre>
<p>
Sometimes the result isn‘t handled directly by a script (such as when
the request comes from a SCRIPT tag), so the <tt>:callback</tt> option is
provided for these cases.
</p>
<pre>
# Renders 'show({"name": "David"})'
render :json => {:name => "David"}.to_json, :callback => 'show'
</pre>
<h3>Rendering an inline template</h3>
<p>
Rendering of an inline template works as a cross between text and action
rendering where the source for the template is supplied inline, like text,
but its interpreted with ERb or Builder, like action. By default, ERb is
used for rendering and the current layout is not used.
</p>
<pre>
# Renders "hello, hello, hello, again"
render :inline => "<%= 'hello, ' * 3 + 'again' %>"
# Renders "<p>Good seeing you!</p>" using Builder
render :inline => "xml.p { 'Good seeing you!' }", :type => :builder
# Renders "hello david"
render :inline => "<%= 'hello ' + name %>", :locals => { :name => "david" }
</pre>
<h3>Rendering inline JavaScriptGenerator page updates</h3>
<p>
In addition to rendering JavaScriptGenerator page updates with Ajax in RJS
templates (see <a href="../ActionView/Base.html">ActionView::Base</a> for
details), you can also pass the <tt>:update</tt> parameter to <tt><a
href="Base.html#M000303">render</a></tt>, along with a block, to <a
href="Base.html#M000303">render</a> page updates inline.
</p>
<pre>
render :update do |page|
page.replace_html 'user_list', :partial => 'user', :collection => @users
page.visual_effect :highlight, 'user_list'
end
</pre>
<h3>Rendering vanilla JavaScript</h3>
<p>
In addition to using RJS with <a href="Base.html#M000303">render</a>
:update, you can also just <a href="Base.html#M000303">render</a> vanilla
JavaScript with :js.
</p>
<pre>
# Renders "alert('hello')" and sets the mime type to text/javascript
render :js => "alert('hello')"
</pre>
<h3>Rendering with status and location headers</h3>
<p>
All renders take the <tt>:status</tt> and <tt>:location</tt> options and
turn them into headers. They can even be used together:
</p>
<pre>
render :xml => post.to_xml, :status => :created, :location => post_url(post)
</pre>
</div>
</div>
<div id="method-M000304" class="method-detail">
<a name="M000304"></a>
<div class="method-heading">
<a href="Base.src/M000304.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000304.html');return false;">
<span class="method-name">render_to_string</span><span class="method-args">(options = nil, &block)</span>
</a>
</div>
<div class="method-description">
<p>
Renders according to the same rules as <tt><a
href="Base.html#M000303">render</a></tt>, but returns the result in a
string instead of sending it as the response body to the browser.
</p>
</div>
</div>
<div id="method-M000313" class="method-detail">
<a name="M000313"></a>
<div class="method-heading">
<a href="Base.src/M000313.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000313.html');return false;">
<span class="method-name">reset_session</span><span class="method-args">(</span>
</a>
</div>
<div class="method-description">
<p>
Resets the session by clearing out all the objects stored within and
initializing a new session object.
</p>
</div>
</div>
<div id="method-M000309" class="method-detail">
<a name="M000309"></a>
<div class="method-heading">
<a href="Base.src/M000309.html" target="Code" class="method-signature"
onclick="popupCode('Base.src/M000309.html');return false;">
<span class="method-name">stale?</span><span class="method-args">(options)</span>
</a>
</div>
<div class="method-description">
<p>
Sets the etag and/or last_modified on the response and checks it against
the client request. If the request doesn‘t match the options
provided, the request is considered stale and should be generated from
scratch. Otherwise, it‘s fresh and we don‘t need to generate
anything and a reply of "304 Not Modified" is sent.
</p>
<p>
Parameters:
</p>
<ul>
<li><tt>:etag</tt>
</li>
<li><tt>:last_modified</tt>
</li>
<li><tt>:public</tt> By default the Cache-Control header is private, set this
to true if you want your application to be cachable by other devices (proxy
caches).
</li>
</ul>
<p>
Example:
</p>
<pre>
def show
@article = Article.find(params[:id])
if stale?(:etag => @article, :last_modified => @article.created_at.utc)
@statistics = @article.really_expensive_call
respond_to do |format|
# all the supported formats
end
end
end
</pre>
</div>
</div>
</div>
</div>
<div id="validator-badges">
<p><small><a href="http://validator.w3.org/check/referer">[Validate]</a></small></p>
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</body>
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distrib
>
Mandriva
>
2010.0
>
i586
>
media
>
contrib-release
>
by-pkgid
>
8b99df826c3b6cf56a1caaae5f931d50
>
files
>
181
