require 'active_support/core_ext/object/blank' 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 PARTIAL_NAMES = Hash.new {|h,k| h[k] = {} } def initialize(view_context, options, block) @view = view_context @partial_names = PARTIAL_NAMES[@view.controller.class.name] setup(options, block) end def setup(options, block) partial = options[:partial] @options = options @locals = options[:locals] || {} @block = block if String === partial @object = options[:object] @path = partial @collection = collection else @object = partial if @collection = collection paths = @collection_paths = @collection.map { |o| partial_path(o) } @path = paths.uniq.size == 1 ? paths.first : nil else @path = partial_path end end end def render identifier = ((@template = find_template) ? @template.identifier : @path) if @collection ActiveSupport::Notifications.instrument("action_view.render_collection", :identifier => identifier || "collection", :count => @collection.size) do render_collection end else content = ActiveSupport::Notifications.instrument("action_view.render_partial", :identifier => identifier) do render_partial end if !@block && (layout = @options[:layout]) content = @view._render_layout(find_template(layout), @locals){ content } end content end end def render_collection return nil if @collection.blank? if @options.key?(:spacer_template) spacer = find_template(@options[:spacer_template]).render(@view, @locals) end result = @template ? collection_with_template : collection_without_template result.join(spacer).html_safe end def collection_with_template(template = @template) segments, locals, as, template = [], @locals, @options[:as] || @template.variable_name, @template counter_name = template.counter_name locals[counter_name] = -1 @collection.each do |object| locals[counter_name] += 1 locals[as] = object segments << template.render(@view, locals) end segments end def collection_without_template(collection_paths = @collection_paths) segments, locals, as = [], @locals, @options[:as] index, template = -1, nil @collection.each_with_index do |object, i| template = find_template(collection_paths[i]) locals[template.counter_name] = (index += 1) locals[as || template.variable_name] = object segments << template.render(@view, locals) end @template = template segments end def render_partial(object = @object) locals, view, template = @locals, @view, @template object ||= locals[template.variable_name] locals[@options[:as] || template.variable_name] = object template.render(view, locals) do |*name| view._layout_for(*name, &@block) end end private def collection if @object.respond_to?(:to_ary) @object elsif @options.key?(:collection) @options[:collection] || [] end end def find_template(path=@path) return path unless path.is_a?(String) prefix = @view.controller_path unless path.include?(?/) @view.find_template(path, prefix, true) end def partial_path(object = @object) @partial_names[object.class.name] ||= begin object = object.to_model if object.respond_to?(:to_model) object.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, &block) #:nodoc: if defined?(@renderer) @renderer.setup(options, block) else @renderer = PartialRenderer.new(self, options, block) end @renderer.render end end end