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: $<%= user.budget %> # Title: <%= chief.name %> #
# # As you can see, the :locals hash is shared between both the partial and its layout. module Partials private def render_partial(partial_path, object_assigns = nil, local_assigns = {}) #:nodoc: case partial_path when String, Symbol, NilClass # Render the template ActionView::PartialTemplate.new(self, partial_path, object_assigns, local_assigns).render_template when ActionView::Helpers::FormBuilder builder_partial_path = partial_path.class.to_s.demodulize.underscore.sub(/_builder$/, '') 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), partial_path, local_assigns) end end def render_partial_collection(partial_path, collection, partial_spacer_template = nil, local_assigns = {}) #:nodoc: return " " if collection.empty? local_assigns = local_assigns ? local_assigns.clone : {} spacer = partial_spacer_template ? render(:partial => partial_spacer_template) : '' if partial_path.nil? render_partial_collection_with_unknown_partial_path(collection, local_assigns) else render_partial_collection_with_known_partial_path(collection, partial_path, local_assigns) end.join(spacer) end def render_partial_collection_with_known_partial_path(collection, partial_path, local_assigns) template = ActionView::PartialTemplate.new(self, partial_path, nil, local_assigns) collection.map do |element| template.render_member(element) end end def render_partial_collection_with_unknown_partial_path(collection, local_assigns) templates = Hash.new i = 0 collection.map do |element| partial_path = ActionController::RecordIdentifier.partial_path(element) template = templates[partial_path] ||= ActionView::PartialTemplate.new(self, partial_path, nil, local_assigns) template.counter = i i += 1 template.render_member(element) end end end end