1 module ActionController
#:nodoc:
3 def self.included(base
)
4 base
.extend(ClassMethods
)
7 alias_method_chain
:inherited, :layout
12 # Layouts reverse the common pattern of including shared headers and footers in many templates to isolate changes in
13 # repeated setups. The inclusion pattern has pages that look like this:
15 # <%= render "shared/header" %>
17 # <%= render "shared/footer" %>
19 # This approach is a decent way of keeping common structures isolated from the changing content, but it's verbose
20 # and if you ever want to change the structure of these two includes, you'll have to change all the templates.
22 # With layouts, you can flip it around and have the common structure know where to insert changing content. This means
23 # that the header and footer are only mentioned in one place, like this:
25 # // The header part of this layout
27 # // The footer part of this layout
29 # And then you have content pages that look like this:
33 # At rendering time, the content page is computed and then inserted in the layout, like this:
35 # // The header part of this layout
37 # // The footer part of this layout
39 # NOTE: The old notation for rendering the view from a layout was to expose the magic <tt>@content_for_layout</tt> instance
40 # variable. The preferred notation now is to use <tt>yield</tt>, as documented above.
42 # == Accessing shared variables
44 # Layouts have access to variables specified in the content pages and vice versa. This allows you to have layouts with
45 # references that won't materialize before rendering time:
47 # <h1><%= @page_title %></h1>
50 # ...and content pages that fulfill these references _at_ rendering time:
52 # <% @page_title = "Welcome" %>
53 # Off-world colonies offers you a chance to start a new life
55 # The result after rendering is:
58 # Off-world colonies offers you a chance to start a new life
60 # == Automatic layout assignment
62 # If there is a template in <tt>app/views/layouts/</tt> with the same name as the current controller then it will be automatically
63 # set as that controller's layout unless explicitly told otherwise. Say you have a WeblogController, for example. If a template named
64 # <tt>app/views/layouts/weblog.erb</tt> or <tt>app/views/layouts/weblog.builder</tt> exists then it will be automatically set as
65 # the layout for your WeblogController. You can create a layout with the name <tt>application.erb</tt> or <tt>application.builder</tt>
66 # and this will be set as the default controller if there is no layout with the same name as the current controller and there is
67 # no layout explicitly assigned with the +layout+ method. Nested controllers use the same folder structure for automatic layout.
68 # assignment. So an Admin::WeblogController will look for a template named <tt>app/views/layouts/admin/weblog.erb</tt>.
69 # Setting a layout explicitly will always override the automatic behaviour for the controller where the layout is set.
70 # Explicitly setting the layout in a parent class, though, will not override the child class's layout assignment if the child
71 # class has a layout with the same name.
73 # == Inheritance for layouts
75 # Layouts are shared downwards in the inheritance hierarchy, but not upwards. Examples:
77 # class BankController < ActionController::Base
78 # layout "bank_standard"
80 # class InformationController < BankController
82 # class VaultController < BankController
83 # layout :access_level_layout
85 # class EmployeeController < BankController
88 # The InformationController uses "bank_standard" inherited from the BankController, the VaultController overwrites
89 # and picks the layout dynamically, and the EmployeeController doesn't want to use a layout at all.
93 # Layouts are basically just regular templates, but the name of this template needs not be specified statically. Sometimes
94 # you want to alternate layouts depending on runtime information, such as whether someone is logged in or not. This can
95 # be done either by specifying a method reference as a symbol or using an inline method (as a proc).
97 # The method reference is the preferred approach to variable layouts and is used like this:
99 # class WeblogController < ActionController::Base
100 # layout :writers_and_readers
107 # def writers_and_readers
108 # logged_in? ? "writer_layout" : "reader_layout"
111 # Now when a new request for the index action is processed, the layout will vary depending on whether the person accessing
112 # is logged in or not.
114 # If you want to use an inline method, such as a proc, do something like this:
116 # class WeblogController < ActionController::Base
117 # layout proc{ |controller| controller.logged_in? ? "writer_layout" : "reader_layout" }
119 # Of course, the most common way of specifying a layout is still just as a plain template name:
121 # class WeblogController < ActionController::Base
122 # layout "weblog_standard"
124 # If no directory is specified for the template name, the template will by default be looked for in <tt>app/views/layouts/</tt>.
125 # Otherwise, it will be looked up relative to the template root.
127 # == Conditional layouts
129 # If you have a layout that by default is applied to all the actions of a controller, you still have the option of rendering
130 # a given action or set of actions without a layout, or restricting a layout to only a single action or a set of actions. The
131 # <tt>:only</tt> and <tt>:except</tt> options can be passed to the layout call. For example:
133 # class WeblogController < ActionController::Base
134 # layout "weblog_standard", :except => :rss
140 # This will assign "weblog_standard" as the WeblogController's layout except for the +rss+ action, which will not wrap a layout
141 # around the rendered view.
143 # Both the <tt>:only</tt> and <tt>:except</tt> condition can accept an arbitrary number of method references, so
144 # #<tt>:except => [ :rss, :text_only ]</tt> is valid, as is <tt>:except => :rss</tt>.
146 # == Using a different layout in the action render call
148 # If most of your actions use the same layout, it makes perfect sense to define a controller-wide layout as described above.
149 # Sometimes you'll have exceptions where one action wants to use a different layout than the rest of the controller.
150 # You can do this by passing a <tt>:layout</tt> option to the <tt>render</tt> call. For example:
152 # class WeblogController < ActionController::Base
153 # layout "weblog_standard"
156 # render :action => "help", :layout => "help"
160 # This will render the help action with the "help" layout instead of the controller-wide "weblog_standard" layout.
162 # If a layout is specified, all rendered actions will have their result rendered
163 # when the layout <tt>yield</tt>s. This layout can itself depend on instance variables assigned during action
164 # performance and have access to them as any normal template would.
165 def layout(template_name
, conditions
= {}, auto
= false)
166 add_layout_conditions(conditions
)
167 write_inheritable_attribute(:layout, template_name
)
168 write_inheritable_attribute(:auto_layout, auto
)
171 def layout_conditions
#:nodoc:
172 @layout_conditions ||= read_inheritable_attribute(:layout_conditions)
175 def layout_list
#:nodoc:
176 Array(view_paths
).sum([]) { |path
| Dir
["#{path.to_str}/layouts/**/*"] }
180 def inherited_with_layout(child
)
181 inherited_without_layout(child
)
182 unless child
.name
.blank
?
183 layout_match
= child
.name
.underscore
.sub(/_controller$/, '').sub(/^controllers\//, '')
184 child
.layout(layout_match
, {}, true) unless child
.layout_list
.grep(%r
{layouts
/#{layout_match}(\.[a-z][0-9a-z]*)+$}).empty?
188 def add_layout_conditions(conditions
)
189 write_inheritable_hash(:layout_conditions, normalize_conditions(conditions
))
192 def normalize_conditions(conditions
)
193 conditions
.inject({}) {|hash
, (key
, value
)| hash
.merge(key
=> [value
].flatten
.map
{|action
| action
.to_s
})}
197 # Returns the name of the active layout. If the layout was specified as a method reference (through a symbol), this method
198 # is called and the return value is used. Likewise if the layout was specified as an inline method (through a proc or method
199 # object). If the layout was defined without a directory, layouts is assumed. So <tt>layout "weblog/standard"</tt> will return
200 # weblog/standard, but <tt>layout "standard"</tt> will return layouts/standard.
201 def active_layout(passed_layout
= nil, options
= {})
202 layout
= passed_layout
|| default_layout
203 return layout
if layout
.respond_to
?(:render)
205 active_layout
= case layout
206 when Symbol
then __send__(layout
)
207 when Proc
then layout
.call(self)
211 find_layout(active_layout
, default_template_format
, options
[:html_fallback]) if active_layout
215 def default_layout
#:nodoc:
216 layout
= self.class.read_inheritable_attribute(:layout)
217 return layout
unless self.class.read_inheritable_attribute(:auto_layout)
218 find_layout(layout
, default_template_format
)
219 rescue ActionView
::MissingTemplate
223 def find_layout(layout
, format
, html_fallback
=false) #:nodoc:
224 view_paths
.find_template(layout
.to_s
=~
/layouts\// ? layout : "layouts/#{layout}", format, html_fallback)
225 rescue ActionView
::MissingTemplate
226 raise if Mime
::Type.lookup_by_extension(format
.to_s
).html
?
229 def pick_layout(options
)
230 if options
.has_key
?(:layout)
231 case layout
= options
.delete(:layout)
234 when NilClass
, TrueClass
235 active_layout
if action_has_layout
? && candidate_for_layout
?(:template => default_template_name
)
237 active_layout(layout
, :html_fallback => true)
240 active_layout
if action_has_layout
? && candidate_for_layout
?(options
)
244 def action_has_layout
?
245 if conditions
= self.class.layout_conditions
247 when only
= conditions
[:only]
248 only
.include?(action_name
)
249 when except
= conditions
[:except]
250 !except
.include?(action_name
)
259 def candidate_for_layout
?(options
)
260 template
= options
[:template] || default_template(options
[:action])
261 if options
.values_at(:text, :xml, :json, :file, :inline, :partial, :nothing, :update).compact
.empty
?
263 template_object
= self.view_paths
.find_template(template
, default_template_format
)
264 # this restores the behavior from 2.2.2, where response.template.template_format was reset
265 # to :html for :js requests with a matching html template.
266 # see v2.2.2, ActionView::Base, lines 328-330
267 @real_format = :html if response
.template
.template_format
== :js && template_object
.format
== "html"
268 !template_object
.exempt_from_layout
?
269 rescue ActionView
::MissingTemplate
273 rescue ActionView
::MissingTemplate
277 def default_template_format
278 @real_format || response
.template
.template_format