require 'erb'
module ActionView #:nodoc:
class ActionViewError < StandardError #:nodoc:
end
# Action View templates can be written in two ways. If the template file has a +.rhtml+ extension then it uses a mixture of ERb
# (included in Ruby) and HTML. If the template file has a +.rxml+ extension then Jim Weirich's Builder::XmlMarkup library is used.
#
# = ERb
#
# You trigger ERb by using embeddings such as <% %> and <%= %>. The difference is whether you want output or not. Consider the
# following loop for names:
#
# <b>Names of all the people</b>
# <% for person in @people %>
# Name: <%= person.name %><br/>
# <% end %>
#
# The loop is setup in regular embedding tags (<% %>) and the name is written using the output embedding tag (<%= %>). Note that this
# is not just a usage suggestion. Regular output functions like print or puts won't work with ERb templates. So this would be wrong:
#
# Hi, Mr. <% puts "Frodo" %>
#
# (If you absolutely must write from within a function, you can use the TextHelper#concat)
#
# == Using sub templates
#
# Using sub templates allows you to sidestep tedious replication and extract common display structures in shared templates. The
# classic example is the use of a header and footer (even though the Action Pack-way would be to use Layouts):
#
# <%= render "shared/header" %>
# Something really specific and terrific
# <%= render "shared/footer" %>
#
# As you see, we use the output embeddings for the render methods. The render call itself will just return a string holding the
# result of the rendering. The output embedding writes it to the current template.
#
# But you don't have to restrict yourself to static includes. Templates can share variables amongst themselves by using instance
# variables defined in using the regular embedding tags. Like this:
#
# <% @page_title = "A Wonderful Hello" %>
# <%= render "shared/header" %>
#
# Now the header can pick up on the @page_title variable and use it for outputting a title tag:
#
# <title><%= @page_title %></title>
#
# == Passing local variables to sub templates
#
# You can pass local variables to sub templates by using a hash with the variable names as keys and the objects as values:
#
# <%= render "shared/header", { "headline" => "Welcome", "person" => person } %>
#
# These can now be accessed in shared/header with:
#
# Headline: <%= headline %>
# First name: <%= person.first_name %>
#
# == Template caching
#
# The parsing of ERb templates are cached by default, but the reading of them are not. This means that the application by default
# will reflect changes to the templates immediatly. If you'd like to sacrifice that immediacy for the speed gain given by also
# caching the loading of templates (reading from the file system), you can turn that on with
# <tt>ActionView::Base.cache_template_loading = true</tt>.
#
# == Builder
#
# Builder templates are a more programmatic alternative to ERb. They are especially useful for generating XML content. An +XmlMarkup+ object
# named +xml+ is automatically made available to templates with a +.rxml+ extension.
#
# Here are some basic examples:
#
# xml.em("emphasized") # => <em>emphasized</em>
# xml.em { xml.b("emp & bold") } # => <em><b>emph & bold</b></em>
# xml.a("A Link", "href"=>"http://onestepback.org") # => <a href="http://onestepback.org">A Link</a>
# xm.target("name"=>"compile", "option"=>"fast") # => <target option="fast" name="compile"\>
# # NOTE: order of attributes is not specified.
#
# Any method with a block will be treated as an XML markup tag with nested markup in the block. For example, the following:
#
# xml.div {
# xml.h1(@person.name)
# xml.p(@person.bio)
# }
#
# would produce something like:
#
# <div>
# <h1>David Heinemeier Hansson</h1>
# <p>A product of Danish Design during the Winter of '79...</p>
# </div>
#
# A full-length RSS example actually used on Basecamp:
#
# xml.rss("version" => "2.0", "xmlns:dc" => "http://purl.org/dc/elements/1.1/") do
# xml.channel do
# xml.title(@feed_title)
# xml.link(@url)
# xml.description "Basecamp: Recent items"
# xml.language "en-us"
# xml.ttl "40"
#
# for item in @recent_items
# xml.item do
# xml.title(item_title(item))
# xml.description(item_description(item)) if item_description(item)
# xml.pubDate(item_pubDate(item))
# xml.guid(@person.firm.account.url + @recent_items.url(item))
# xml.link(@person.firm.account.url + @recent_items.url(item))
#
# xml.tag!("dc:creator", item.author_name) if item_has_creator?(item)
# end
# end
# end
# end
#
# More builder documentation can be found at http://builder.rubyforge.org.
class Base
include ERB::Util
attr_reader :first_render
attr_accessor :base_path, :assigns, :template_extension
attr_accessor :controller
# Turn on to cache the reading of templates from the file system. Doing so means that you have to restart the server
# when changing templates, but that rendering will be faster.
@@cache_template_loading = false
cattr_accessor :cache_template_loading
@@compiled_erb_templates = {}
@@loaded_templates = {}
@@template_handlers = {}
def self.load_helpers(helper_dir)#:nodoc:
Dir.foreach(helper_dir) do |helper_file|
next unless helper_file =~ /_helper.rb$/
require helper_dir + helper_file
helper_module_name = helper_file.capitalize.gsub(/_([a-z])/) { |m| $1.capitalize }[0..-4]
class_eval("include ActionView::Helpers::#{helper_module_name}") if Helpers.const_defined?(helper_module_name)
end
end
def self.controller_delegate(*methods)#:nodoc:
methods.flatten.each do |method|
class_eval <<-end_eval
def #{method}(*args, &block)
controller.send(%(#{method}), *args, &block)
end
end_eval
end
end
def self.register_template_handler(extension, klass)
@@template_handlers[extension] = klass
end
def initialize(base_path = nil, assigns_for_first_render = {}, controller = nil)#:nodoc:
@base_path, @assigns = base_path, assigns_for_first_render
@controller = controller
end
# Renders the template present at <tt>template_path</tt>. If <tt>use_full_path</tt> is set to true,
# it's relative to the template_root, otherwise it's absolute. The hash in <tt>local_assigns</tt>
# is made available as local variables.
def render_file(template_path, use_full_path = true, local_assigns = {})
@first_render = template_path if @first_render.nil?
if use_full_path
template_extension = pick_template_extension(template_path)
template_file_name = full_template_path(template_path, template_extension)
else
template_file_name = template_path
template_extension = template_path.split(".").last
end
template_source = read_template_file(template_file_name)
begin
render_template(template_extension, template_source, local_assigns)
rescue Exception => e
if TemplateError === e
e.sub_template_of(template_file_name)
raise e
else
raise TemplateError.new(@base_path, template_file_name, @assigns, template_source, e)
end
end
end
# Renders the template present at <tt>template_path</tt> (relative to the template_root).
# The hash in <tt>local_assigns</tt> is made available as local variables.
def render(template_path, local_assigns = {})
render_file(template_path, true, local_assigns)
end
# Renders the +template+ which is given as a string as either rhtml or rxml depending on <tt>template_extension</tt>.
# The hash in <tt>local_assigns</tt> is made available as local variables.
def render_template(template_extension, template, local_assigns = {})
send(pick_rendering_method(template_extension), template_extension,
template, local_assigns)
end
def pick_template_extension(template_path)#:nodoc:
if match = delegate_template_exists?(template_path)
match.first
elsif erb_template_exists?(template_path)
"rhtml"
elsif builder_template_exists?(template_path)
"rxml"
else
raise ActionViewError, "No rhtml, rxml, or delegate template found for #{template_path}"
end
end
def pick_rendering_method(template_extension)#:nodoc:
if @@template_handlers[template_extension]
"delegate_render"
else
(template_extension == "rxml" ? "rxml" : "rhtml") + "_render"
end
end
def delegate_template_exists?(template_path)#:nodoc:
@@template_handlers.find { |k,| template_exists?(template_path, k) }
end
def erb_template_exists?(template_path)#:nodoc:
template_exists?(template_path, "rhtml")
end
def builder_template_exists?(template_path)#:nodoc:
template_exists?(template_path, "rxml")
end
def file_exists?(template_path)#:nodoc:
erb_template_exists?(template_path) || builder_template_exists?(template_path) || delegate_template_exists?(template_path)
end
# Returns true is the file may be rendered implicitly.
def file_public?(template_path)#:nodoc:
template_path.split("/").last[0,1] != "_"
end
private
def full_template_path(template_path, extension)
"#{@base_path}/#{template_path}.#{extension}"
end
def template_exists?(template_path, extension)
(cache_template_loading && @@loaded_templates.has_key?(template_path)) ||
FileTest.exists?(full_template_path(template_path, extension))
end
def read_template_file(template_path)
unless cache_template_loading && @@loaded_templates[template_path]
@@loaded_templates[template_path] = File.read(template_path)
end
@@loaded_templates[template_path]
end
def evaluate_locals(local_assigns = {})
b = binding
local_assigns.each { |key, value| eval "#{key} = local_assigns[\"#{key}\"]", b }
@assigns.each { |key, value| instance_variable_set "@#{key}", value }
xml = Builder::XmlMarkup.new(:indent => 2)
b
end
def rhtml_render(extension, template, local_assigns)
b = evaluate_locals(local_assigns)
@@compiled_erb_templates[template] ||= ERB.new(template, nil, '-')
@@compiled_erb_templates[template].result(b)
end
def rxml_render(extension, template, local_assigns)
@controller.headers["Content-Type"] ||= 'text/xml'
eval(template, evaluate_locals(local_assigns))
end
def delegate_render(extension, template, local_assigns)
delegator = @@template_handlers[extension].new(self)
delegator.render(template, local_assigns)
end
end
end
require 'action_view/template_error'
