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