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Cleaning up and documenting AbstractController::Layouts

This commit is contained in:
Yehuda Katz + Carl Lerche 2009-06-09 16:46:42 -07:00
parent acb2447785
commit f35f47b8c0
5 changed files with 255 additions and 43 deletions

View file

@ -5,16 +5,26 @@ module AbstractController
include Renderer
included do
extlib_inheritable_accessor :_layout_conditions
self._layout_conditions = {}
extlib_inheritable_accessor(:_layout_conditions) { Hash.new }
end
module ClassMethods
# Specify the layout to use for this class.
#
# If the specified layout is a:
# String:: the String is the template name
# Symbol:: call the method specified by the symbol, which will return
# the template name
# false:: There is no layout
# true:: raise an ArgumentError
#
# ==== Parameters
# layout<String, Symbol, false)>:: The layout to use.
#
# ==== Options (conditions)
# :only<#to_s, Array[#to_s]>:: A list of actions to apply this layout to.
# :except<#to_s, Array[#to_s]>:: Apply this layout to all actions but this one
def layout(layout, conditions = {})
unless [String, Symbol, FalseClass, NilClass].include?(layout.class)
raise ArgumentError, "Layouts must be specified as a String, Symbol, false, or nil"
end
conditions.each {|k, v| conditions[k] = Array(v).map {|a| a.to_s} }
self._layout_conditions = conditions
@ -22,6 +32,11 @@ module AbstractController
_write_layout_method
end
# If no layout is supplied, look for a template named the return
# value of this method.
#
# ==== Returns
# String:: A template name
def _implied_layout_name
name.underscore
end
@ -29,23 +44,31 @@ module AbstractController
# Takes the specified layout and creates a _layout method to be called
# by _default_layout
#
# If the specified layout is a:
# String:: return the string
# Symbol:: call the method specified by the symbol
# false:: return nil
# none:: If a layout is found in the view paths with the controller's
# name, return that string. Otherwise, use the superclass'
# layout (which might also be implied)
# If there is no explicit layout specified:
# If a layout is found in the view paths with the controller's
# name, return that string. Otherwise, use the superclass'
# layout (which might also be implied)
def _write_layout_method
case @_layout
when String
self.class_eval %{def _layout(details) #{@_layout.inspect} end}
when Symbol
self.class_eval %{def _layout(details) #{@_layout} end}
self.class_eval <<-ruby_eval, __FILE__, __LINE__ + 1
def _layout(details)
#{@_layout}.tap do |layout|
unless layout.is_a?(String) || !layout
raise ArgumentError, "Your layout method :#{@_layout} returned \#{layout}. It " \
"should have returned a String, false, or nil"
end
end
end
ruby_eval
when false
self.class_eval %{def _layout(details) end}
else
self.class_eval %{
when true
raise ArgumentError, "Layouts must be specified as a String, Symbol, false, or nil"
when nil
self.class_eval <<-ruby_eval, __FILE__, __LINE__ + 1
def _layout(details)
if view_paths.find_by_parts?("#{_implied_layout_name}", details, "layouts")
"#{_implied_layout_name}"
@ -53,33 +76,54 @@ module AbstractController
super
end
end
}
ruby_eval
end
end
end
private
# This will be overwritten
def _layout(details)
end
# This will be overwritten by _write_layout_method
def _layout(details) end
# :api: plugin
# ====
# Override this to mutate the inbound layout name
# Determine the layout for a given name and details.
#
# ==== Parameters
# name<String>:: The name of the template
# details<Hash{Symbol => Object}>:: A list of details to restrict
# the lookup to. By default, layout lookup is limited to the
# formats specified for the current request.
def _layout_for_name(name, details = {:formats => formats})
unless [String, FalseClass, NilClass].include?(name.class)
raise ArgumentError, "String, false, or nil expected; you passed #{name.inspect}"
end
name && view_paths.find_by_parts(name, details, _layout_prefix(name))
name && _find_by_parts(name, details)
end
# TODO: Decide if this is the best hook point for the feature
def _layout_prefix(name)
"layouts"
# Take in the name and details and find a Template.
#
# ==== Parameters
# name<String>:: The name of the template to retrieve
# details<Hash>:: A list of details to restrict the search by. This
# might include details like the format or locale of the template.
#
# ==== Returns
# Template:: A template object matching the name and details
def _find_by_parts(name, details)
# TODO: Make prefix actually part of details in ViewPath#find_by_parts
prefix = details.key?(:prefix) ? details.delete(:prefix) : "layouts"
view_paths.find_by_parts(name, details, prefix)
end
def _default_layout(require_layout = false, details = {:formats => formats})
# Returns the default layout for this controller and a given set of details.
# Optionally raises an exception if the layout could not be found.
#
# ==== Parameters
# details<Hash>:: A list of details to restrict the search by. This
# might include details like the format or locale of the template.
# require_layout<Boolean>:: If this is true, raise an ArgumentError
# with details about the fact that the exception could not be
# found (defaults to false)
#
# ==== Returns
# Template:: The template object for the default layout (or nil)
def _default_layout(details, require_layout = false)
if require_layout && _action_has_layout? && !_layout(details)
raise ArgumentError,
"There was no default layout for #{self.class} in #{view_paths.inspect}"
@ -93,6 +137,12 @@ module AbstractController
end
end
# Determines whether the current action has a layout by checking the
# action name against the :only and :except conditions set on the
# layout.
#
# ==== Returns
# Boolean:: True if the action has a layout, false otherwise.
def _action_has_layout?
conditions = _layout_conditions
if only = conditions[:only]

View file

@ -114,8 +114,9 @@ module ActionController
super || (respond_to?(:method_missing) && "_handle_method_missing")
end
def _layout_prefix(name)
super unless name =~ /\blayouts/
def _find_by_parts(name, details)
details[:prefix] = nil if name =~ /\blayouts/
super
end
def performed?

View file

@ -1,4 +1,163 @@
module ActionController
# 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
#
# == Layout assignment
#
# You can either specify a layout declaratively (using the #layout class method) or give
# it the same name as your controller, and place it in <tt>app/views/layouts</tt>.
# If a subclass does not have a layout specified, it inherits its layout using normal Ruby inheritance.
#
# For instance, if you have PostsController and a template named <tt>app/views/layouts/posts.html.erb</tt>,
# that template will be used for all actions in PostsController and controllers inheriting
# from PostsController.
#
# If you use a module, for instance Weblog::PostsController, you will need a template named
# <tt>app/views/layouts/weblog/posts.html.erb</tt>.
#
# Since all your controllers inherit from ApplicationController, they will use
# <tt>app/views/layouts/application.html.erb</tt> if no other layout is specified
# or provided.
#
# == Inheritance Examples
#
# class BankController < ActionController::Base
# layout "bank_standard"
#
# class InformationController < BankController
#
# class TellerController < BankController
# # teller.html.erb exists
#
# class TillController < TellerController
#
# 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.
#
# The TellerController uses +teller.html.erb+, and TillController inherits that layout and
# uses it as well.
#
# == 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 Layouts
extend ActiveSupport::Concern
@ -6,6 +165,7 @@ module ActionController
include AbstractController::Layouts
module ClassMethods
# If no layout is provided, look for a layout with this name.
def _implied_layout_name
controller_path
end
@ -14,16 +174,17 @@ module ActionController
private
def _determine_template(options)
super
if (!options.key?(:text) && !options.key?(:inline) && !options.key?(:partial)) || options.key?(:layout)
options[:_layout] = _layout_for_option(options.key?(:layout) ? options[:layout] : :none, options[:_template].details)
end
return if (options.key?(:text) || options.key?(:inline) || options.key?(:partial)) && !options.key?(:layout)
layout = options.key?(:layout) ? options[:layout] : :none
options[:_layout] = _layout_for_option(layout, options[:_template].details)
end
def _layout_for_option(name, details)
case name
when String then _layout_for_name(name, details)
when true then _default_layout(true, details)
when :none then _default_layout(false, details)
when true then _default_layout(details, true)
when :none then _default_layout(details, false)
when false, nil then nil
else
raise ArgumentError,

View file

@ -154,7 +154,7 @@ module AbstractController
end
def render_to_body(options = {})
options[:_layout] = options[:layout] || _default_layout
options[:_layout] = options[:layout] || _default_layout({})
super
end
end

View file

@ -25,7 +25,7 @@ module AbstractControllerTests
def controller_path() self.class.controller_path end
def render_to_body(options)
options[:_layout] = _default_layout
options[:_layout] = _default_layout({})
super
end
end
@ -221,11 +221,11 @@ module AbstractControllerTests
test "raises an exception when specifying layout true" do
assert_raises ArgumentError do
Object.class_eval <<-RUBY_EVAL, __FILE__, __LINE__ + 1
Object.class_eval do
class ::BadOmgFailLolLayout < AbstractControllerTests::Layouts::Base
layout true
end
RUBY_EVAL
end
end
end
end