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Diffstat (limited to 'actionview/lib/action_view/renderer/partial_renderer.rb')
-rw-r--r-- | actionview/lib/action_view/renderer/partial_renderer.rb | 492 |
1 files changed, 492 insertions, 0 deletions
diff --git a/actionview/lib/action_view/renderer/partial_renderer.rb b/actionview/lib/action_view/renderer/partial_renderer.rb new file mode 100644 index 0000000000..821026268a --- /dev/null +++ b/actionview/lib/action_view/renderer/partial_renderer.rb @@ -0,0 +1,492 @@ +require 'thread_safe' + +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 <tt>ActionView::PartialRenderer</tt> doesn't have any local variables. + # The <tt>:object</tt> option can be used to pass an object to the partial. For instance: + # + # <%= render partial: "account", object: @buyer %> + # + # would provide the <tt>@buyer</tt> object to the partial, available under the local variable +account+ and is + # equivalent to: + # + # <%= render partial: "account", locals: { account: @buyer } %> + # + # With the <tt>:as</tt> 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 <tt>:as</tt> option may be used when rendering partials. + # + # You can specify a partial to be rendered between elements via the <tt>:spacer_template</tt> option. + # The following example will render <tt>advertiser/_ad_divider.html.erb</tt> between each ad partial: + # + # <%= render partial: "ad", collection: @advertisements, spacer_template: "ad_divider" %> + # + # If the given <tt>:collection</tt> is nil or empty, <tt>render</tt> 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 &> + # <div id="administrator"> + # Budget: $<%= user.budget %> + # <%= yield %> + # </div> + # + # <%# app/views/users/_editor.html.erb &> + # <div id="editor"> + # Deadline: <%= user.deadline %> + # <%= yield %> + # </div> + # + # ...this will return: + # + # Here's the administrator: + # <div id="administrator"> + # Budget: $<%= user.budget %> + # Name: <%= user.name %> + # </div> + # + # Here's the editor: + # <div id="editor"> + # Deadline: <%= user.deadline %> + # Name: <%= user.name %> + # </div> + # + # 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 %> + # <ul> + # <% users.each do |user| -%> + # <li> + # <%= render partial: "user", locals: { user: user } %> + # </li> + # <% end -%> + # </ul> + # + # <%# app/views/users/_li_layout.html.erb %> + # <li> + # <%= yield %> + # </li> + # + # <%# app/views/users/index.html.erb %> + # <ul> + # <%= render partial: "user", layout: "li_layout", collection: users %> + # </ul> + # + # Given two users whose names are Alice and Bob, these snippets return: + # + # <ul> + # <li> + # Name: Alice + # </li> + # <li> + # Name: Bob + # </li> + # </ul> + # + # 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: + # + # <div id="administrator"> + # Budget: $<%= user.budget %> + # Title: <%= chief.name %> + # </div> + # + # As you can see, the <tt>:locals</tt> 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 &> + # <div class="user"> + # Budget: $<%= user.budget %> + # <%= yield user %> + # </div> + # + # <%# 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 &> + # <div class="user"> + # <%= yield user, :header %> + # Budget: $<%= user.budget %> + # <%= yield user, :footer %> + # </div> + # + # <%# 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 = ThreadSafe::Cache.new do |h, k| + h[k] = ThreadSafe::Cache.new + end + + 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.to_s, @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 + + # Sets up instance variables needed for rendering a partial. This method + # finds the options and details and extracts them. The method also contains + # logic that handles the type of object passed in as the partial. + # + # If +options[:partial]+ is a string, then the +@path+ instance variable is + # set to that string. Otherwise, the +options[:partial]+ object must + # respond to +to_partial_path+ in order to setup the path. + 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 + + # Obtains the path to where the object's partial is located. If the object + # responds to +to_partial_path+, then +to_partial_path+ will be called and + # will provide the path. If the object does not respond to +to_partial_path+, + # then an +ArgumentError+ is raised. + # + # If +prefix_partial_path_with_controller_namespace+ is true, then this + # method will prefix the partial paths with a namespace. + 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 if @object || @collection + 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 |