module ActionView # There's also a convenience method for rendering sub templates within the current controller that depends on a # single object (we call this kind of sub templates for partials). It relies on the fact that partials should # follow the naming convention of being prefixed with an underscore -- as to separate them from regular # templates that could be rendered on their own. # # In a template for Advertiser#account: # # <%= render :partial => "account" %> # # This would render "advertiser/_account.erb" and pass the instance variable @account in as a local variable # +account+ to the template for display. # # In another template for Advertiser#buy, we could have: # # <%= render :partial => "account", :locals => { :account => @buyer } %> # # <% for ad in @advertisements %> # <%= render :partial => "ad", :locals => { :ad => ad } %> # <% end %> # # This would first render "advertiser/_account.erb" with @buyer passed in as the local variable +account+, then # render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display. # # == Rendering a collection of partials # # The example of partial use describes a familiar pattern where a template needs to iterate over an array and # render a sub template for each of the elements. This pattern has been implemented as a single method that # accepts an array and renders a partial by the same name as the elements contained within. So the three-lined # example in "Using partials" can be rewritten with a single line: # # <%= render :partial => "ad", :collection => @advertisements %> # # This will render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display. An # iteration counter will automatically be made available to the template with a name of the form # +partial_name_counter+. In the case of the example above, the template would be fed +ad_counter+. # # NOTE: Due to backwards compatibility concerns, the collection can't be one of hashes. Normally you'd also # just keep domain objects, like Active Records, in there. # # == Rendering shared partials # # Two controllers can share a set of partials and render them like this: # # <%= render :partial => "advertisement/ad", :locals => { :ad => @advertisement } %> # # This will render the partial "advertisement/_ad.erb" regardless of which controller this is being called from. # # == Rendering objects with the RecordIdentifier # # Instead of explicitly naming the location of a partial, you can also let the RecordIdentifier do the work if # you're following its conventions for RecordIdentifier#partial_path. Examples: # # # @account is an Account instance, so it uses the RecordIdentifier to replace # # <%= render :partial => "accounts/account", :locals => { :account => @buyer } %> # <%= render :partial => @account %> # # # @posts is an array of Post instances, so it uses the RecordIdentifier to replace # # <%= render :partial => "posts/post", :collection => @posts %> # <%= render :partial => @posts %> # # == Rendering the default case # # If you're not going to be using any of the options like collections or layouts, you can also use the short-hand # defaults of render to render partials. Examples: # # # Instead of <%= render :partial => "account" %> # <%= render "account" %> # # # Instead of <%= render :partial => "account", :locals => { :account => @buyer } %> # <%= render "account", :account => @buyer %> # # # @account is an Account instance, so it uses the RecordIdentifier to replace # # <%= render :partial => "accounts/account", :locals => { :account => @account } %> # <%= render(@account) %> # # # @posts is an array of Post instances, so it uses the RecordIdentifier to replace # # <%= render :partial => "posts/post", :collection => @posts %> # <%= render(@posts) %> # # == Rendering partials with layouts # # Partials can have their own layouts applied to them. These layouts are different than the ones that are # specified globally for the entire action, but they work in a similar fashion. Imagine a list with two types # of users: # # <%# app/views/users/index.html.erb &> # Here's the administrator: # <%= render :partial => "user", :layout => "administrator", :locals => { :user => administrator } %> # # Here's the editor: # <%= render :partial => "user", :layout => "editor", :locals => { :user => editor } %> # # <%# app/views/users/_user.html.erb &> # Name: <%= user.name %> # # <%# app/views/users/_administrator.html.erb &> #
# Budget: $<%= user.budget %> # <%= yield %> #
# # <%# app/views/users/_editor.html.erb &> #
# Deadline: <%= user.deadline %> # <%= yield %> #
# # ...this will return: # # Here's the administrator: #
# Budget: $<%= user.budget %> # Name: <%= user.name %> #
# # Here's the editor: #
# Deadline: <%= user.deadline %> # Name: <%= user.name %> #
# # You can also apply a layout to a block within any template: # # <%# app/views/users/_chief.html.erb &> # <% render(:layout => "administrator", :locals => { :user => chief }) do %> # Title: <%= chief.title %> # <% end %> # # ...this will return: # #
# Budget: $<%= user.budget %> # Title: <%= chief.name %> #
# # As you can see, the :locals hash is shared between both the partial and its layout. # # If you pass arguments to "yield" then this will be passed to the block. One way to use this is to pass # an array to layout and treat it as an enumerable. # # <%# app/views/users/_user.html.erb &> #
# Budget: $<%= user.budget %> # <%= yield user %> #
# # <%# app/views/users/index.html.erb &> # <% render :layout => @users do |user| %> # Title: <%= user.title %> # <% end %> # # This will render the layout for each user and yield to the block, passing the user, each time. # # You can also yield multiple times in one layout and use block arguments to differentiate the sections. # # <%# app/views/users/_user.html.erb &> #
# <%= yield user, :header %> # Budget: $<%= user.budget %> # <%= yield user, :footer %> #
# # <%# app/views/users/index.html.erb &> # <% render :layout => @users do |user, section| %> # <%- case section when :header -%> # Title: <%= user.title %> # <%- when :footer -%> # Deadline: <%= user.deadline %> # <%- end -%> # <% end %> module Partials extend ActiveSupport::Concern class PartialRenderer def self.partial_names @partial_names ||= Hash.new {|h,k| h[k] = ActiveSupport::ConcurrentHash.new } end def self.formats @formats ||= Hash.new {|h,k| h[k] = Hash.new{|h,k| h[k] = Hash.new {|h,k| h[k] = {}}}} end def initialize(view_context, options, block) partial = options[:partial] @view = view_context @options = options @locals = options[:locals] || {} @block = block # Set up some instance variables to speed up memoizing @partial_names = self.class.partial_names[@view.controller.class] @templates = self.class.formats @format = view_context.formats # Set up the object and path @object = partial.is_a?(String) ? options[:object] : partial @path = partial_path(partial) end def render return render_collection if collection template = find_template render_template(template, @object || @locals[template.variable_name]) end def render_collection # Even if no template is rendered, this will ensure that the MIME type # for the empty response is the same as the provided template @options[:_template] = default_template = find_template return nil if collection.blank? if @options.key?(:spacer_template) spacer = find_template(@options[:spacer_template]).render(@view, @locals) end segments = [] collection.each_with_index do |object, index| template = default_template || find_template(partial_path(object)) @locals[template.counter_name] = index segments << render_template(template, object) end segments.join(spacer) end def render_template(template, object = @object) @options[:_template] ||= template # TODO: is locals[:object] really necessary? @locals[:object] = @locals[template.variable_name] = object @locals[@options[:as]] = object if @options[:as] content = @view._render_single_template(template, @locals, &@block) return content if @block || !@options[:layout] find_template(@options[:layout]).render(@view, @locals) { content } end private def collection @collection ||= if @object.respond_to?(:to_ary) @object elsif @options.key?(:collection) @options[:collection] || [] end end def find_template(path = @path) return if !path @templates[path][@view.controller_path][@format][I18n.locale] ||= begin prefix = @view.controller.controller_path unless path.include?(?/) @view.find(path, {:formats => @view.formats}, prefix, true) end end def partial_path(object = @object) return object if object.is_a?(String) @partial_names[object.class] ||= begin return nil unless object.respond_to?(:to_model) object.to_model.class.model_name.partial_path.dup.tap do |partial| path = @view.controller_path partial.insert(0, "#{File.dirname(path)}/") if path.include?(?/) end end end end def render_partial(options) @assigns_added = false # TODO: Handle other details here. self.formats = options[:_details][:formats] if options[:_details] _render_partial(options) end def _render_partial(options, &block) #:nodoc: PartialRenderer.new(self, options, block).render end end end