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". # # 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::PartialRenderer doesn't have any local variables. # The :object option can be used to pass an object to the partial. For instance: # # <%= render partial: "account", object: @buyer %> # # would provide the @buyer object to the partial, available under the local variable +account+ and is # equivalent to: # # <%= render partial: "account", locals: { account: @buyer } %> # # With the :as option we can specify a different name for said local variable. For example, if we # wanted it to be +user+ instead of +account+ we'd do: # # <%= render partial: "account", object: @buyer, as: 'user' %> # # This is equivalent to # # <%= render partial: "account", locals: { user: @buyer } %> # # == 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 that respond to `to_partial_path` # # Instead of explicitly naming the location of a partial, you can also let PartialRenderer do the work # and pick the proper path by checking `to_partial_path` method. # # # @account.to_partial_path returns 'accounts/account', so it can be used to replace: # # <%= render partial: "accounts/account", locals: { account: @account} %> # <%= render partial: @account %> # # # @posts is an array of Post instances, so every post record returns 'posts/post' on `to_partial_path`, # # that's why we can 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.to_partial_path returns 'accounts/account', so it can be used to replace: # # <%= render partial: "accounts/account", locals: { account: @account} %> # <%= render @account %> # # # @posts is an array of Post instances, so every post record returns 'posts/post' on `to_partial_path`, # # that's why we can 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 %> #
# # If a collection is given, the layout will be rendered once for each item in # the collection. Just think these two snippets have the same output: # # <%# app/views/users/_user.html.erb %> # Name: <%= user.name %> # # <%# app/views/users/index.html.erb %> # <%# This does not use layouts %> # # # <%# app/views/users/_li_layout.html.erb %> #
  • # <%= yield %> #
  • # # <%# app/views/users/index.html.erb %> # # # Given two users whose names are Alice and Bob, these snippets return: # # # # The current object being rendered, as well as the object_counter, will be # available as local variables inside the layout template under the same names # as available in the partial. # # 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 PREFIXED_PARTIAL_NAMES = Hash.new { |h,k| h[k] = {} } def initialize(*) super @context_prefix = @lookup_context.prefixes.first end def render(context, options, block) setup(context, options, block) identifier = (@template = find_partial) ? @template.identifier : @path @lookup_context.rendered_format ||= begin if @template && @template.formats.present? @template.formats.first else formats.first end end 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 def render_collection return nil if @collection.blank? if @options.key?(:spacer_template) spacer = find_template(@options[:spacer_template], @locals.keys).render(@view, @locals) end result = @template ? collection_with_template : collection_without_template result.join(spacer).html_safe end def render_partial view, locals, block = @view, @locals, @block object, as = @object, @variable if !block && (layout = @options[:layout]) layout = find_template(layout, @template_keys) 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 @details = extract_details(options) prepend_formats(options[:formats]) 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 as = options[:as] raise_invalid_identifier(as) unless as.to_s =~ /\A[a-z_]\w*\z/ as = as.to_sym end if @path @variable, @variable_counter = retrieve_variable(@path, as) @template_keys = retrieve_template_keys else paths.map! { |path| retrieve_variable(path, as).unshift(path) } end self end def collection if @options.key?(:collection) collection = @options[:collection] collection.respond_to?(:to_ary) ? collection.to_ary : [] end end def collection_from_object @object.to_ary if @object.respond_to?(:to_ary) end def find_partial if path = @path find_template(path, @template_keys) end end def find_template(path, locals) prefixes = path.include?(?/) ? [] : @lookup_context.prefixes @lookup_context.find_template(path, prefixes, true, locals, @details) end def collection_with_template view, locals, template = @view, @locals, @template as, counter = @variable, @variable_counter if layout = @options[:layout] layout = find_template(layout, @template_keys) end index = -1 @collection.map do |object| locals[as] = object locals[counter] = (index += 1) content = template.render(view, locals) content = layout.render(view, locals) { content } if layout content end end def collection_without_template view, locals, collection_data = @view, @locals, @collection_data cache = {} keys = @locals.keys index = -1 @collection.map do |object| index += 1 path, as, counter = collection_data[index] locals[as] = object locals[counter] = index template = (cache[path] ||= find_template(path, keys + [as, counter])) template.render(view, locals) end end def partial_path(object = @object) object = object.to_model if object.respond_to?(:to_model) path = if object.respond_to?(:to_partial_path) object.to_partial_path else raise ArgumentError.new("'#{object.inspect}' is not an ActiveModel-compatible object. It must implement :to_partial_path.") end if @view.prefix_partial_path_with_controller_namespace prefixed_partial_names[path] ||= merge_prefix_into_object_path(@context_prefix, path.dup) else path end end def prefixed_partial_names @prefixed_partial_names ||= PREFIXED_PARTIAL_NAMES[@context_prefix] end def merge_prefix_into_object_path(prefix, object_path) if prefix.include?(?/) && object_path.include?(?/) prefixes = [] prefix_array = File.dirname(prefix).split('/') object_path_array = object_path.split('/')[0..-3] # skip model dir & partial prefix_array.each_with_index do |dir, index| break if dir == object_path_array[index] prefixes << dir end (prefixes << object_path).join("/") else object_path end end def retrieve_template_keys keys = @locals.keys keys << @variable keys << @variable_counter if @collection keys end def retrieve_variable(path, as) variable = as || begin base = path[-1] == "/" ? "" : File.basename(path) raise_invalid_identifier(path) unless base =~ /\A_?([a-z]\w*)(\.\w+)*\z/ $1.to_sym end variable_counter = :"#{variable}_counter" if @collection [variable, variable_counter] end IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " + "make sure your partial name starts with a lowercase letter or underscore, " + "and is followed by any combination of letters, numbers and underscores." def raise_invalid_identifier(path) raise ArgumentError.new(IDENTIFIER_ERROR_MESSAGE % (path)) end end end