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: $<%= user.budget %> # <%= yield user, :footer %> #
# # <%# app/views/users/index.html.erb &> # <% render :layout => @users do |user, section| %> # <%- case section when :header -%> # Title: <%= user.title %> # <%- when :footer -%> # Deadline: <%= user.deadline %> # <%- end -%> # <% end %> module Partials extend ActiveSupport::Memoizable private def render_partial(options = {}) #:nodoc: local_assigns = options[:locals] || {} case partial_path = options[:partial] when String, Symbol, NilClass if options.has_key?(:collection) render_partial_collection(options) else _pick_partial_template(partial_path).render_partial(self, options[:object], local_assigns) end when ActionView::Helpers::FormBuilder builder_partial_path = partial_path.class.to_s.demodulize.underscore.sub(/_builder$/, '') local_assigns.merge!(builder_partial_path.to_sym => partial_path) render_partial(:partial => builder_partial_path, :object => options[:object], :locals => local_assigns) else if Array === partial_path || (defined?(ActiveRecord) && (ActiveRecord::Associations::AssociationCollection === partial_path || ActiveRecord::NamedScope::Scope === partial_path)) render_partial_collection(options.except(:partial).merge(:collection => partial_path)) else object = partial_path render_partial( :partial => ActionController::RecordIdentifier.partial_path(object, controller.class.controller_path), :object => object, :locals => local_assigns ) end end end def render_partial_collection(options = {}) #:nodoc: return nil if options[:collection].blank? partial = options[:partial] spacer = options[:spacer_template] ? render(:partial => options[:spacer_template]) : '' local_assigns = options[:locals] ? options[:locals].clone : {} as = options[:as] index = 0 options[:collection].map do |object| _partial_path ||= partial || ActionController::RecordIdentifier.partial_path(object, controller.class.controller_path) template = _pick_partial_template(_partial_path) local_assigns[template.counter_name] = index result = template.render_partial(self, object, local_assigns.dup, as) index += 1 result end.join(spacer).html_safe! end def _pick_partial_template(partial_path) #:nodoc: if partial_path.include?('/') path = File.join(File.dirname(partial_path), "_#{File.basename(partial_path)}") elsif controller path = "#{controller.class.controller_path}/_#{partial_path}" else path = "_#{partial_path}" end self.view_paths.find_template(path, self.template_format) end memoize :_pick_partial_template end end