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Diffstat (limited to 'guides/source/layouts_and_rendering.md')
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diff --git a/guides/source/layouts_and_rendering.md b/guides/source/layouts_and_rendering.md index c3cde49630..c57fa358d6 100644 --- a/guides/source/layouts_and_rendering.md +++ b/guides/source/layouts_and_rendering.md @@ -1,4 +1,4 @@ -**DO NOT READ THIS FILE IN GITHUB, GUIDES ARE PUBLISHED IN http://guides.rubyonrails.org.** +**DO NOT READ THIS FILE ON GITHUB, GUIDES ARE PUBLISHED ON http://guides.rubyonrails.org.** Layouts and Rendering in Rails ============================== @@ -255,7 +255,7 @@ extension for the layout file. #### Rendering HTML -You can send a HTML string back to the browser by using the `:html` option to +You can send an HTML string back to the browser by using the `:html` option to `render`: ```ruby @@ -316,12 +316,13 @@ NOTE: Unless overridden, your response returned from this render option will be #### Options for `render` -Calls to the `render` method generally accept four options: +Calls to the `render` method generally accept five options: * `:content_type` * `:layout` * `:location` * `:status` +* `:formats` ##### The `:content_type` Option @@ -427,9 +428,19 @@ Rails understands both numeric status codes and the corresponding symbols shown | | 510 | :not_extended | | | 511 | :network_authentication_required | -NOTE: If you try to render content along with a non-content status code +NOTE: If you try to render content along with a non-content status code (100-199, 204, 205 or 304), it will be dropped from the response. +##### The `:formats` Option + +Rails uses the format specified in the request (or `:html` by default). You can +change this passing the `:formats` option with a symbol or an array: + +```ruby +render formats: :xml +render formats: [:json, :xml] +``` + #### Finding Layouts To find the current layout, Rails first looks for a file in `app/views/layouts` with the same base name as the controller. For example, rendering actions from the `PhotosController` class will use `app/views/layouts/photos.html.erb` (or `app/views/layouts/photos.builder`). If there is no such controller-specific layout, Rails will use `app/views/layouts/application.html.erb` or `app/views/layouts/application.builder`. If there is no `.erb` layout, Rails will use a `.builder` layout if one exists. Rails also provides several ways to more precisely assign specific layouts to individual controllers and actions. @@ -553,6 +564,42 @@ In this application: * `OldArticlesController#show` will use no layout at all * `OldArticlesController#index` will use the `old` layout +##### Template Inheritance + +Similar to the Layout Inheritance logic, if a template or partial is not found in the conventional path, the controller will look for a template or partial to render in its inheritance chain. For example: + +```ruby +# in app/controllers/application_controller +class ApplicationController < ActionController::Base +end + +# in app/controllers/admin_controller +class AdminController < ApplicationController +end + +# in app/controllers/admin/products_controller +class Admin::ProductsController < AdminController + def index + end +end +``` + +The lookup order for a `admin/products#index` action will be: + +* `app/views/admin/products/` +* `app/views/admin/` +* `app/views/application/` + +This makes `app/views/application/` a great place for your shared partials, which can then be rendered in your ERB as such: + +```erb +<%# app/views/admin/products/index.html.erb %> +<%= render @products || "empty_list" %> + +<%# app/views/application/_empty_list.html.erb %> +There are no items in this list <em>yet</em>. +``` + #### Avoiding Double Render Errors Sooner or later, most Rails developers will see the error message "Can only render or redirect once per action". While this is annoying, it's relatively easy to fix. Usually it happens because of a fundamental misunderstanding of the way that `render` works. @@ -1039,7 +1086,7 @@ As you already could see from the previous sections of this guide, `yield` is a <p> Name contains: <%= f.text_field :name_contains %> </p> - <%= end %> + <% end %> ``` * `roles/index.html.erb` @@ -1049,7 +1096,7 @@ As you already could see from the previous sections of this guide, `yield` is a <p> Title contains: <%= f.text_field :title_contains %> </p> - <%= end %> + <% end %> ``` * `shared/_search_filters.html.erb` @@ -1114,6 +1161,36 @@ You can also pass local variables into partials, making them even more powerful Although the same partial will be rendered into both views, Action View's submit helper will return "Create Zone" for the new action and "Update Zone" for the edit action. +To pass a local variable to a partial in only specific cases use the `local_assigns`. + +* `index.html.erb` + + ```erb + <%= render user.articles %> + ``` + +* `show.html.erb` + + ```erb + <%= render article, full: true %> + ``` + +* `_articles.html.erb` + + ```erb + <%= content_tag_for :article, article do |article| %> + <h2><%= article.title %></h2> + + <% if local_assigns[:full] %> + <%= simple_format article.body %> + <% else %> + <%= truncate article.body %> + <% end %> + <% end %> + ``` + +This way it is possible to use the partial without the need to declare all local variables. + Every partial also has a local variable with the same name as the partial (minus the underscore). You can pass an object in to this local variable via the `:object` option: ```erb |