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 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: # # # Here's the administrator: # <%= render :partial => "user", :layout => "administrator", :locals => { :user => administrator } %> # # Here's the editor: # <%= render :partial => "user", :layout => "editor", :locals => { :user => editor } %> # # # Name: <%= user.name %> # # #
# Budget: $<%= user.budget %> # <%= yield %> #
# # #
# 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: # # # <% 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. module Partials private def render_partial(partial_path, object_assigns = nil, local_assigns = nil) #:nodoc: case partial_path when String, Symbol, NilClass path, partial_name = partial_pieces(partial_path) object = extracting_object(partial_name, object_assigns) local_assigns = local_assigns ? local_assigns.clone : {} add_counter_to_local_assigns!(partial_name, local_assigns) add_object_to_local_assigns!(partial_name, local_assigns, object) if logger ActionController::Base.benchmark("Rendered #{path}/_#{partial_name}", Logger::DEBUG, false) do render("#{path}/_#{partial_name}", local_assigns) end else render("#{path}/_#{partial_name}", local_assigns) end when Array, ActiveRecord::Associations::AssociationCollection if partial_path.any? path = ActionController::RecordIdentifier.partial_path(partial_path.first) collection = partial_path render_partial_collection(path, collection, nil, object_assigns.value) else "" end else render_partial( ActionController::RecordIdentifier.partial_path(partial_path), object_assigns, local_assigns) end end def render_partial_collection(partial_name, collection, partial_spacer_template = nil, local_assigns = nil) #:nodoc: collection_of_partials = Array.new counter_name = partial_counter_name(partial_name) local_assigns = local_assigns ? local_assigns.clone : {} collection.each_with_index do |element, counter| local_assigns[counter_name] = counter collection_of_partials.push(render_partial(partial_name, element, local_assigns)) end return " " if collection_of_partials.empty? if partial_spacer_template spacer_path, spacer_name = partial_pieces(partial_spacer_template) collection_of_partials.join(render("#{spacer_path}/_#{spacer_name}")) else collection_of_partials.join end end alias_method :render_collection_of_partials, :render_partial_collection def partial_pieces(partial_path) if partial_path.include?('/') return File.dirname(partial_path), File.basename(partial_path) else return controller.class.controller_path, partial_path end end def partial_counter_name(partial_name) "#{partial_variable_name(partial_name)}_counter".intern end def partial_variable_name(partial_name) partial_name.split('/').last.split('.').first.intern end def extracting_object(partial_name, object_assigns) variable_name = partial_variable_name(partial_name) if object_assigns.nil? controller.instance_variable_get("@#{variable_name}") else object_assigns end end def add_counter_to_local_assigns!(partial_name, local_assigns) counter_name = partial_counter_name(partial_name) local_assigns[counter_name] = 1 unless local_assigns.has_key?(counter_name) end def add_object_to_local_assigns!(partial_name, local_assigns, object) variable_name = partial_variable_name(partial_name) local_assigns[variable_name] ||= if object.is_a?(ActionView::Base::ObjectWrapper) object.value else object end || controller.instance_variable_get("@#{variable_name}") end end end