--- /dev/null
+module ActionController #:nodoc:
+ module Layout #:nodoc:
+ def self.included(base)
+ base.extend(ClassMethods)
+ base.class_eval do
+ class << self
+ alias_method_chain :inherited, :layout
+ end
+ end
+ end
+
+ # Layouts reverse the common pattern of including shared headers and footers in many templates to isolate changes in
+ # repeated setups. The inclusion pattern has pages that look like this:
+ #
+ # <%= render "shared/header" %>
+ # Hello World
+ # <%= render "shared/footer" %>
+ #
+ # This approach is a decent way of keeping common structures isolated from the changing content, but it's verbose
+ # and if you ever want to change the structure of these two includes, you'll have to change all the templates.
+ #
+ # With layouts, you can flip it around and have the common structure know where to insert changing content. This means
+ # that the header and footer are only mentioned in one place, like this:
+ #
+ # // The header part of this layout
+ # <%= yield %>
+ # // The footer part of this layout
+ #
+ # And then you have content pages that look like this:
+ #
+ # hello world
+ #
+ # At rendering time, the content page is computed and then inserted in the layout, like this:
+ #
+ # // The header part of this layout
+ # hello world
+ # // The footer part of this layout
+ #
+ # NOTE: The old notation for rendering the view from a layout was to expose the magic <tt>@content_for_layout</tt> instance
+ # variable. The preferred notation now is to use <tt>yield</tt>, as documented above.
+ #
+ # == Accessing shared variables
+ #
+ # Layouts have access to variables specified in the content pages and vice versa. This allows you to have layouts with
+ # references that won't materialize before rendering time:
+ #
+ # <h1><%= @page_title %></h1>
+ # <%= yield %>
+ #
+ # ...and content pages that fulfill these references _at_ rendering time:
+ #
+ # <% @page_title = "Welcome" %>
+ # Off-world colonies offers you a chance to start a new life
+ #
+ # The result after rendering is:
+ #
+ # <h1>Welcome</h1>
+ # Off-world colonies offers you a chance to start a new life
+ #
+ # == Automatic layout assignment
+ #
+ # If there is a template in <tt>app/views/layouts/</tt> with the same name as the current controller then it will be automatically
+ # set as that controller's layout unless explicitly told otherwise. Say you have a WeblogController, for example. If a template named
+ # <tt>app/views/layouts/weblog.erb</tt> or <tt>app/views/layouts/weblog.builder</tt> exists then it will be automatically set as
+ # the layout for your WeblogController. You can create a layout with the name <tt>application.erb</tt> or <tt>application.builder</tt>
+ # 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
+ # no layout explicitly assigned with the +layout+ method. Nested controllers use the same folder structure for automatic layout.
+ # assignment. So an Admin::WeblogController will look for a template named <tt>app/views/layouts/admin/weblog.erb</tt>.
+ # Setting a layout explicitly will always override the automatic behaviour for the controller where the layout is set.
+ # Explicitly setting the layout in a parent class, though, will not override the child class's layout assignment if the child
+ # class has a layout with the same name.
+ #
+ # == Inheritance for layouts
+ #
+ # Layouts are shared downwards in the inheritance hierarchy, but not upwards. Examples:
+ #
+ # class BankController < ActionController::Base
+ # layout "bank_standard"
+ #
+ # class InformationController < BankController
+ #
+ # class VaultController < BankController
+ # layout :access_level_layout
+ #
+ # class EmployeeController < BankController
+ # layout nil
+ #
+ # The InformationController uses "bank_standard" inherited from the BankController, the VaultController overwrites
+ # and picks the layout dynamically, and the EmployeeController doesn't want to use a layout at all.
+ #
+ # == Types of layouts
+ #
+ # Layouts are basically just regular templates, but the name of this template needs not be specified statically. Sometimes
+ # you want to alternate layouts depending on runtime information, such as whether someone is logged in or not. This can
+ # be done either by specifying a method reference as a symbol or using an inline method (as a proc).
+ #
+ # The method reference is the preferred approach to variable layouts and is used like this:
+ #
+ # class WeblogController < ActionController::Base
+ # layout :writers_and_readers
+ #
+ # def index
+ # # fetching posts
+ # end
+ #
+ # private
+ # def writers_and_readers
+ # logged_in? ? "writer_layout" : "reader_layout"
+ # end
+ #
+ # Now when a new request for the index action is processed, the layout will vary depending on whether the person accessing
+ # is logged in or not.
+ #
+ # If you want to use an inline method, such as a proc, do something like this:
+ #
+ # class WeblogController < ActionController::Base
+ # layout proc{ |controller| controller.logged_in? ? "writer_layout" : "reader_layout" }
+ #
+ # Of course, the most common way of specifying a layout is still just as a plain template name:
+ #
+ # class WeblogController < ActionController::Base
+ # layout "weblog_standard"
+ #
+ # If no directory is specified for the template name, the template will by default be looked for in <tt>app/views/layouts/</tt>.
+ # Otherwise, it will be looked up relative to the template root.
+ #
+ # == Conditional layouts
+ #
+ # If you have a layout that by default is applied to all the actions of a controller, you still have the option of rendering
+ # 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
+ # <tt>:only</tt> and <tt>:except</tt> options can be passed to the layout call. For example:
+ #
+ # class WeblogController < ActionController::Base
+ # layout "weblog_standard", :except => :rss
+ #
+ # # ...
+ #
+ # end
+ #
+ # This will assign "weblog_standard" as the WeblogController's layout except for the +rss+ action, which will not wrap a layout
+ # around the rendered view.
+ #
+ # Both the <tt>:only</tt> and <tt>:except</tt> condition can accept an arbitrary number of method references, so
+ # #<tt>:except => [ :rss, :text_only ]</tt> is valid, as is <tt>:except => :rss</tt>.
+ #
+ # == Using a different layout in the action render call
+ #
+ # If most of your actions use the same layout, it makes perfect sense to define a controller-wide layout as described above.
+ # Sometimes you'll have exceptions where one action wants to use a different layout than the rest of the controller.
+ # You can do this by passing a <tt>:layout</tt> option to the <tt>render</tt> call. For example:
+ #
+ # class WeblogController < ActionController::Base
+ # layout "weblog_standard"
+ #
+ # def help
+ # render :action => "help", :layout => "help"
+ # end
+ # end
+ #
+ # This will render the help action with the "help" layout instead of the controller-wide "weblog_standard" layout.
+ module ClassMethods
+ # If a layout is specified, all rendered actions will have their result rendered
+ # when the layout <tt>yield</tt>s. This layout can itself depend on instance variables assigned during action
+ # performance and have access to them as any normal template would.
+ def layout(template_name, conditions = {}, auto = false)
+ add_layout_conditions(conditions)
+ write_inheritable_attribute(:layout, template_name)
+ write_inheritable_attribute(:auto_layout, auto)
+ end
+
+ def layout_conditions #:nodoc:
+ @layout_conditions ||= read_inheritable_attribute(:layout_conditions)
+ end
+
+ def default_layout(format) #:nodoc:
+ layout = read_inheritable_attribute(:layout)
+ return layout unless read_inheritable_attribute(:auto_layout)
+ @default_layout ||= {}
+ @default_layout[format] ||= default_layout_with_format(format, layout)
+ @default_layout[format]
+ end
+
+ def layout_list #:nodoc:
+ Array(view_paths).sum([]) { |path| Dir["#{path}/layouts/**/*"] }
+ end
+
+ private
+ def inherited_with_layout(child)
+ inherited_without_layout(child)
+ unless child.name.blank?
+ layout_match = child.name.underscore.sub(/_controller$/, '').sub(/^controllers\//, '')
+ child.layout(layout_match, {}, true) unless child.layout_list.grep(%r{layouts/#{layout_match}(\.[a-z][0-9a-z]*)+$}).empty?
+ end
+ end
+
+ def add_layout_conditions(conditions)
+ write_inheritable_hash(:layout_conditions, normalize_conditions(conditions))
+ end
+
+ def normalize_conditions(conditions)
+ conditions.inject({}) {|hash, (key, value)| hash.merge(key => [value].flatten.map {|action| action.to_s})}
+ end
+
+ def default_layout_with_format(format, layout)
+ list = layout_list
+ if list.grep(%r{layouts/#{layout}\.#{format}(\.[a-z][0-9a-z]*)+$}).empty?
+ (!list.grep(%r{layouts/#{layout}\.([a-z][0-9a-z]*)+$}).empty? && format == :html) ? layout : nil
+ else
+ layout
+ end
+ end
+ end
+
+ # Returns the name of the active layout. If the layout was specified as a method reference (through a symbol), this method
+ # is called and the return value is used. Likewise if the layout was specified as an inline method (through a proc or method
+ # object). If the layout was defined without a directory, layouts is assumed. So <tt>layout "weblog/standard"</tt> will return
+ # weblog/standard, but <tt>layout "standard"</tt> will return layouts/standard.
+ def active_layout(passed_layout = nil)
+ layout = passed_layout || self.class.default_layout(default_template_format)
+ active_layout = case layout
+ when String then layout
+ when Symbol then __send__(layout)
+ when Proc then layout.call(self)
+ end
+
+ # Explicitly passed layout names with slashes are looked up relative to the template root,
+ # but auto-discovered layouts derived from a nested controller will contain a slash, though be relative
+ # to the 'layouts' directory so we have to check the file system to infer which case the layout name came from.
+ if active_layout
+ if active_layout.include?('/') && ! layout_directory?(active_layout)
+ active_layout
+ else
+ "layouts/#{active_layout}"
+ end
+ end
+ end
+
+ private
+ def candidate_for_layout?(options)
+ options.values_at(:text, :xml, :json, :file, :inline, :partial, :nothing, :update).compact.empty? &&
+ !@template.__send__(:_exempt_from_layout?, options[:template] || default_template_name(options[:action]))
+ end
+
+ def pick_layout(options)
+ if options.has_key?(:layout)
+ case layout = options.delete(:layout)
+ when FalseClass
+ nil
+ when NilClass, TrueClass
+ active_layout if action_has_layout? && !@template.__send__(:_exempt_from_layout?, default_template_name)
+ else
+ active_layout(layout)
+ end
+ else
+ active_layout if action_has_layout? && candidate_for_layout?(options)
+ end
+ end
+
+ def action_has_layout?
+ if conditions = self.class.layout_conditions
+ case
+ when only = conditions[:only]
+ only.include?(action_name)
+ when except = conditions[:except]
+ !except.include?(action_name)
+ else
+ true
+ end
+ else
+ true
+ end
+ end
+
+ def layout_directory?(layout_name)
+ @template.__send__(:_pick_template, "#{File.join('layouts', layout_name)}.#{@template.template_format}") ? true : false
+ rescue ActionView::MissingTemplate
+ false
+ end
+
+ def default_template_format
+ response.template.template_format
+ end
+ end
+end
projects / depot.git / blobdiff