require 'active_support/core_ext/object/blank' module ActionView # = Action View Partials # # 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.html.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 } %> # # <% @advertisements.each do |ad| %> # <%= render :partial => "ad", :locals => { :ad => ad } %> # <% end %> # # This would first render "advertiser/_account.html.erb" with @buyer passed in as the local variable +account+, then # render "advertiser/_ad.html.erb" and pass the local variable +ad+ to the template for display. # # == The :as and :object options # # By default ActionView::Partials::PartialRenderer has its object in a local variable with the same # name as the template. So, given # # <%= render :partial => "contract" %> # # within contract we'll get @contract in the local variable +contract+, as if we had written # # <%= render :partial => "contract", :locals => { :contract => @contract } %> # # With the :as option we can specify a different name for said local variable. For example, if we # wanted it to be +agreement+ instead of +contract+ we'd do: # # <%= render :partial => "contract", :as => 'agreement' %> # # The :object option can be used to directly specify which object is rendered into the partial; # useful when the template's object is elsewhere, in a different ivar or in a local variable for instance. # # Revisiting a previous example we could have written this code: # # <%= render :partial => "account", :object => @buyer %> # # <% @advertisements.each do |ad| %> # <%= render :partial => "ad", :object => ad %> # <% end %> # # The :object and :as options can be used together. # # == 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.html.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+. # # The :as option may be used when rendering partials. # # You can specify a partial to be rendered between elements via the :spacer_template option. # The following example will render advertiser/_ad_divider.html.erb between each ad partial: # # <%= render :partial => "ad", :collection => @advertisements, :spacer_template => "ad_divider" %> # # If the given :collection is nil or empty, render will return nil. This will allow you # to specify a text which will displayed instead by using this form: # # <%= render(:partial => "ad", :collection => @advertisements) || "There's no ad to be displayed" %> # # 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.html.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 => @account} %> # <%= 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 %> class PartialRenderer < AbstractRenderer #:nodoc: PARTIAL_NAMES = Hash.new {|h,k| h[k] = {} } def initialize(*) super @partial_names = PARTIAL_NAMES[@controller.class.name] end def render(context, options, block) setup(context, options, block) wrap_formats(@path) do identifier = ((@template = find_partial) ? @template.identifier : @path) if @collection instrument(:collection, :identifier => identifier || "collection", :count => @collection.size) do render_collection end else instrument(:partial, :identifier => identifier) do render_partial end end 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 render_partial locals, view, block = @locals, @view, @block object, as = @object, @variable if !block && (layout = @options[:layout]) layout = find_template(layout) end object ||= locals[as] locals[as] = object content = @template.render(view, locals) do |*name| view._layout_for(*name, &block) end content = layout.render(view, locals){ content } if layout content end private def setup(context, options, block) @view = context 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_from_object || collection paths = @collection_data = @collection.map { |o| partial_path(o) } @path = paths.uniq.size == 1 ? paths.first : nil else @path = partial_path end end if @path @variable, @variable_counter = retrieve_variable(@path) else paths.map! { |path| retrieve_variable(path).unshift(path) } end self end def controller_prefixes @controller_prefixes ||= @controller && @controller._prefixes end def collection if @options.key?(:collection) collection = @options[:collection] collection.respond_to?(:to_ary) ? collection.to_ary : [] end end def collection_from_object if @object.respond_to?(:to_ary) @object.to_ary end end def find_partial if path = @path locals = @locals.keys locals << @variable locals << @variable_counter if @collection find_template(path, locals) end end def find_template(path=@path, locals=@locals.keys) prefixes = path.include?(?/) ? [] : controller_prefixes @lookup_context.find_template(path, prefixes, true, locals) end def collection_with_template segments, locals, template = [], @locals, @template as, counter = @variable, @variable_counter locals[counter] = -1 @collection.each do |object| locals[counter] += 1 locals[as] = object segments << template.render(@view, locals) end segments end def collection_without_template segments, locals, collection_data = [], @locals, @collection_data index, template, cache = -1, nil, {} keys = @locals.keys @collection.each_with_index do |object, i| path, *data = collection_data[i] template = (cache[path] ||= find_template(path, keys + data)) locals[data[0]] = object locals[data[1]] = (index += 1) segments << template.render(@view, locals) end @template = template segments 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 = controller_prefixes.first partial.insert(0, "#{File.dirname(path)}/") if partial.include?(?/) && path.include?(?/) end end end def retrieve_variable(path) variable = @options[:as].try(:to_sym) || path[%r'_?(\w+)(\.\w+)*$', 1].to_sym variable_counter = :"#{variable}_counter" if @collection [variable, variable_counter] end end end