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<h2>Action View Overview</h2><p>After reading this guide, you will know:</p>
<ul>
<li>What Action View is and how to use it with Rails.</li>
<li>How best to use templates, partials, and layouts.</li>
<li>What helpers are provided by Action View.</li>
<li>How to use localized views.</li>
</ul>
<div id="subCol">
<h3 class="chapter"><img src="images/chapters_icon.gif" alt="" />Chapters</h3>
<ol class="chapters">
<li><a href="#what-is-action-view-questionmark">What is Action View?</a></li>
<li><a href="#using-action-view-with-rails">Using Action View with Rails</a></li>
<li>
<a href="#templates-partials-and-layouts">Templates, Partials, and Layouts</a>
<ul>
<li><a href="#templates">Templates</a></li>
<li><a href="#partials">Partials</a></li>
<li><a href="#layouts">Layouts</a></li>
</ul>
</li>
<li><a href="#partial-layouts">Partial Layouts</a></li>
<li>
<a href="#view-paths">View Paths</a>
<ul>
<li><a href="#prepend-view-path">Prepend view path</a></li>
<li><a href="#append-view-path">Append view path</a></li>
</ul>
</li>
<li>
<a href="#overview-of-helpers-provided-by-action-view">Overview of helpers provided by Action View</a>
<ul>
<li><a href="#assettaghelper">AssetTagHelper</a></li>
<li><a href="#atomfeedhelper">AtomFeedHelper</a></li>
<li><a href="#benchmarkhelper">BenchmarkHelper</a></li>
<li><a href="#cachehelper">CacheHelper</a></li>
<li><a href="#capturehelper">CaptureHelper</a></li>
<li><a href="#datehelper">DateHelper</a></li>
<li><a href="#debughelper">DebugHelper</a></li>
<li><a href="#formhelper">FormHelper</a></li>
<li><a href="#formoptionshelper">FormOptionsHelper</a></li>
<li><a href="#formtaghelper">FormTagHelper</a></li>
<li><a href="#javascripthelper">JavaScriptHelper</a></li>
<li><a href="#numberhelper">NumberHelper</a></li>
<li><a href="#sanitizehelper">SanitizeHelper</a></li>
<li><a href="#csrfhelper">CsrfHelper</a></li>
</ul>
</li>
<li><a href="#localized-views">Localized Views</a></li>
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<h3 id="what-is-action-view-questionmark"><a class="anchorlink" href="#what-is-action-view-questionmark">1 What is Action View?</a></h3><p>In Rails, web requests are handled by <a href="action_controller_overview.html">Action Controller</a> and Action View. Typically, Action Controller is concerned with communicating with the database and performing CRUD actions where necessary. Action View is then responsible for compiling the response.</p><p>Action View templates are written using embedded Ruby in tags mingled with HTML. To avoid cluttering the templates with boilerplate code, a number of helper classes provide common behavior for forms, dates, and strings. It's also easy to add new helpers to your application as it evolves.</p><div class="note"><p>Some features of Action View are tied to Active Record, but that doesn't mean Action View depends on Active Record. Action View is an independent package that can be used with any sort of Ruby libraries.</p></div><h3 id="using-action-view-with-rails"><a class="anchorlink" href="#using-action-view-with-rails">2 Using Action View with Rails</a></h3><p>For each controller there is an associated directory in the <code>app/views</code> directory which holds the template files that make up the views associated with that controller. These files are used to display the view that results from each controller action.</p><p>Let's take a look at what Rails does by default when creating a new resource using the scaffold generator:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
$ rails generate scaffold article
[...]
invoke scaffold_controller
create app/controllers/articles_controller.rb
invoke erb
create app/views/articles
create app/views/articles/index.html.erb
create app/views/articles/edit.html.erb
create app/views/articles/show.html.erb
create app/views/articles/new.html.erb
create app/views/articles/_form.html.erb
[...]
</pre>
</div>
<p>There is a naming convention for views in Rails. Typically, the views share their name with the associated controller action, as you can see above.
For example, the index controller action of the <code>articles_controller.rb</code> will use the <code>index.html.erb</code> view file in the <code>app/views/articles</code> directory.
The complete HTML returned to the client is composed of a combination of this ERB file, a layout template that wraps it, and all the partials that the view may reference. Within this guide you will find more detailed documentation about each of these three components.</p><h3 id="templates-partials-and-layouts"><a class="anchorlink" href="#templates-partials-and-layouts">3 Templates, Partials, and Layouts</a></h3><p>As mentioned, the final HTML output is a composition of three Rails elements: <code>Templates</code>, <code>Partials</code> and <code>Layouts</code>.
Below is a brief overview of each of them.</p><h4 id="templates"><a class="anchorlink" href="#templates">3.1 Templates</a></h4><p>Action View templates can be written in several ways. If the template file has a <code>.erb</code> extension then it uses a mixture of ERB (Embedded Ruby) and HTML. If the template file has a <code>.builder</code> extension then the <code>Builder::XmlMarkup</code> library is used.</p><p>Rails supports multiple template systems and uses a file extension to distinguish amongst them. For example, an HTML file using the ERB template system will have <code>.html.erb</code> as a file extension.</p><h5 id="erb"><a class="anchorlink" href="#erb">3.1.1 ERB</a></h5><p>Within an ERB template, Ruby code can be included using both <code><% %></code> and <code><%= %></code> tags. The <code><% %></code> tags are used to execute Ruby code that does not return anything, such as conditions, loops, or blocks, and the <code><%= %></code> tags are used when you want output.</p><p>Consider the following loop for names:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<h1>Names of all the people</h1>
<% @people.each do |person| %>
Name: <%= person.name %><br>
<% end %>
</pre>
</div>
<p>The loop is set up using regular embedding tags (<code><% %></code>) and the name is inserted using the output embedding tags (<code><%= %></code>). Note that this is not just a usage suggestion: regular output functions such as <code>print</code> and <code>puts</code> won't be rendered to the view with ERB templates. So this would be wrong:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%# WRONG %>
Hi, Mr. <% puts "Frodo" %>
</pre>
</div>
<p>To suppress leading and trailing whitespaces, you can use <code><%-</code> <code>-%></code> interchangeably with <code><%</code> and <code>%></code>.</p><h5 id="builder"><a class="anchorlink" href="#builder">3.1.2 Builder</a></h5><p>Builder templates are a more programmatic alternative to ERB. They are especially useful for generating XML content. An XmlMarkup object named <code>xml</code> is automatically made available to templates with a <code>.builder</code> extension.</p><p>Here are some basic examples:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
xml.em("emphasized")
xml.em { xml.b("emph & bold") }
xml.a("A Link", "href" => "http://rubyonrails.org")
xml.target("name" => "compile", "option" => "fast")
</pre>
</div>
<p>which would produce:</p><div class="code_container">
<pre class="brush: xml; gutter: false; toolbar: false">
<em>emphasized</em>
<em><b>emph &amp; bold</b></em>
<a href="http://rubyonrails.org">A link</a>
<target option="fast" name="compile" />
</pre>
</div>
<p>Any method with a block will be treated as an XML markup tag with nested markup in the block. For example, the following:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
xml.div {
xml.h1(@person.name)
xml.p(@person.bio)
}
</pre>
</div>
<p>would produce something like:</p><div class="code_container">
<pre class="brush: xml; gutter: false; toolbar: false">
<div>
<h1>David Heinemeier Hansson</h1>
<p>A product of Danish Design during the Winter of '79...</p>
</div>
</pre>
</div>
<p>Below is a full-length RSS example actually used on Basecamp:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
xml.rss("version" => "2.0", "xmlns:dc" => "http://purl.org/dc/elements/1.1/") do
xml.channel do
xml.title(@feed_title)
xml.link(@url)
xml.description "Basecamp: Recent items"
xml.language "en-us"
xml.ttl "40"
for item in @recent_items
xml.item do
xml.title(item_title(item))
xml.description(item_description(item)) if item_description(item)
xml.pubDate(item_pubDate(item))
xml.guid(@person.firm.account.url + @recent_items.url(item))
xml.link(@person.firm.account.url + @recent_items.url(item))
xml.tag!("dc:creator", item.author_name) if item_has_creator?(item)
end
end
end
end
</pre>
</div>
<h5 id="jbuilder"><a class="anchorlink" href="#jbuilder">3.1.3 Jbuilder</a></h5><p><a href="https://github.com/rails/jbuilder">Jbuilder</a> is a gem that's
maintained by the Rails team and included in the default Rails <code>Gemfile</code>.
It's similar to Builder, but is used to generate JSON, instead of XML.</p><p>If you don't have it, you can add the following to your <code>Gemfile</code>:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
gem 'jbuilder'
</pre>
</div>
<p>A Jbuilder object named <code>json</code> is automatically made available to templates with
a <code>.jbuilder</code> extension.</p><p>Here is a basic example:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
json.name("Alex")
json.email("[email protected]")
</pre>
</div>
<p>would produce:</p><div class="code_container">
<pre class="brush: plain; gutter: false; toolbar: false">
{
"name": "Alex",
"email": "[email protected]"
}
</pre>
</div>
<p>See the <a href="https://github.com/rails/jbuilder#jbuilder">Jbuilder documentation</a> for
more examples and information.</p><h5 id="template-caching"><a class="anchorlink" href="#template-caching">3.1.4 Template Caching</a></h5><p>By default, Rails will compile each template to a method in order to render it. When you alter a template, Rails will check the file's modification time and recompile it in development mode.</p><h4 id="partials"><a class="anchorlink" href="#partials">3.2 Partials</a></h4><p>Partial templates - usually just called "partials" - are another device for breaking the rendering process into more manageable chunks. With partials, you can extract pieces of code from your templates to separate files and also reuse them throughout your templates.</p><h5 id="naming-partials"><a class="anchorlink" href="#naming-partials">3.2.1 Naming Partials</a></h5><p>To render a partial as part of a view, you use the <code>render</code> method within the view:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render "menu" %>
</pre>
</div>
<p>This will render a file named <code>_menu.html.erb</code> at that point within the view that is being rendered. Note the leading underscore character: partials are named with a leading underscore to distinguish them from regular views, even though they are referred to without the underscore. This holds true even when you're pulling in a partial from another folder:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render "shared/menu" %>
</pre>
</div>
<p>That code will pull in the partial from <code>app/views/shared/_menu.html.erb</code>.</p><h5 id="using-partials-to-simplify-views"><a class="anchorlink" href="#using-partials-to-simplify-views">3.2.2 Using Partials to simplify Views</a></h5><p>One way to use partials is to treat them as the equivalent of subroutines; a way to move details out of a view so that you can grasp what's going on more easily. For example, you might have a view that looks like this:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render "shared/ad_banner" %>
<h1>Products</h1>
<p>Here are a few of our fine products:</p>
<% @products.each do |product| %>
<%= render partial: "product", locals: { product: product } %>
<% end %>
<%= render "shared/footer" %>
</pre>
</div>
<p>Here, the <code>_ad_banner.html.erb</code> and <code>_footer.html.erb</code> partials could contain content that is shared among many pages in your application. You don't need to see the details of these sections when you're concentrating on a particular page.</p><h5 id="render-without-partial-and-locals-options"><a class="anchorlink" href="#render-without-partial-and-locals-options">3.2.3 <code>render</code> without <code>partial</code> and <code>locals</code> options</a></h5><p>In the above example, <code>render</code> takes 2 options: <code>partial</code> and <code>locals</code>. But if
these are the only options you want to pass, you can skip using these options.
For example, instead of:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: "product", locals: { product: @product } %>
</pre>
</div>
<p>You can also do:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render "product", product: @product %>
</pre>
</div>
<h5 id="the-as-and-object-options"><a class="anchorlink" href="#the-as-and-object-options">3.2.4 The <code>as</code> and <code>object</code> options</a></h5><p>By default <code>ActionView::Partials::PartialRenderer</code> has its object in a local variable with the same name as the template. So, given:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: "product" %>
</pre>
</div>
<p>within <code>_product</code> partial we'll get <code>@product</code> in the local variable <code>product</code>,
as if we had written:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: "product", locals: { product: @product } %>
</pre>
</div>
<p>The <code>object</code> option can be used to directly specify which object is rendered into the partial; useful when the template's object is elsewhere (e.g. in a different instance variable or in a local variable).</p><p>For example, instead of:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: "product", locals: { product: @item } %>
</pre>
</div>
<p>we would do:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: "product", object: @item %>
</pre>
</div>
<p>With the <code>as</code> option we can specify a different name for the said local variable. For example, if we wanted it to be <code>item</code> instead of <code>product</code> we would do:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: "product", object: @item, as: "item" %>
</pre>
</div>
<p>This is equivalent to</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: "product", locals: { item: @item } %>
</pre>
</div>
<h5 id="rendering-collections"><a class="anchorlink" href="#rendering-collections">3.2.5 Rendering Collections</a></h5><p>It is very common that a template will need to iterate over a collection 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 for each one of the elements in the array.</p><p>So this example for rendering all the products:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<% @products.each do |product| %>
<%= render partial: "product", locals: { product: product } %>
<% end %>
</pre>
</div>
<p>can be rewritten in a single line:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: "product", collection: @products %>
</pre>
</div>
<p>When a partial is called with a collection, the individual instances of the partial have access to the member of the collection being rendered via a variable named after the partial. In this case, the partial is <code>_product</code>, and within it you can refer to <code>product</code> to get the collection member that is being rendered.</p><p>You can use a shorthand syntax for rendering collections. Assuming <code>@products</code> is a collection of <code>Product</code> instances, you can simply write the following to produce the same result:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render @products %>
</pre>
</div>
<p>Rails determines the name of the partial to use by looking at the model name in the collection, <code>Product</code> in this case. In fact, you can even render a collection made up of instances of different models using this shorthand, and Rails will choose the proper partial for each member of the collection.</p><h5 id="spacer-templates"><a class="anchorlink" href="#spacer-templates">3.2.6 Spacer Templates</a></h5><p>You can also specify a second partial to be rendered between instances of the main partial by using the <code>:spacer_template</code> option:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: @products, spacer_template: "product_ruler" %>
</pre>
</div>
<p>Rails will render the <code>_product_ruler</code> partial (with no data passed to it) between each pair of <code>_product</code> partials.</p><h4 id="layouts"><a class="anchorlink" href="#layouts">3.3 Layouts</a></h4><p>Layouts can be used to render a common view template around the results of Rails controller actions. Typically, a Rails application will have a couple of layouts that pages will be rendered within. For example, a site might have one layout for a logged in user and another for the marketing or sales side of the site. The logged in user layout might include top-level navigation that should be present across many controller actions. The sales layout for a SaaS app might include top-level navigation for things like "Pricing" and "Contact Us" pages. You would expect each layout to have a different look and feel. You can read about layouts in more detail in the <a href="layouts_and_rendering.html">Layouts and Rendering in Rails</a> guide.</p><h3 id="partial-layouts"><a class="anchorlink" href="#partial-layouts">4 Partial Layouts</a></h3><p>Partials can have their own layouts applied to them. These layouts are different from those applied to a controller action, but they work in a similar fashion.</p><p>Let's say we're displaying an article on a page which should be wrapped in a <code>div</code> for display purposes. Firstly, we'll create a new <code>Article</code>:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
Article.create(body: 'Partial Layouts are cool!')
</pre>
</div>
<p>In the <code>show</code> template, we'll render the <code>_article</code> partial wrapped in the <code>box</code> layout:</p><p><strong>articles/show.html.erb</strong></p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= render partial: 'article', layout: 'box', locals: { article: @article } %>
</pre>
</div>
<p>The <code>box</code> layout simply wraps the <code>_article</code> partial in a <code>div</code>:</p><p><strong>articles/_box.html.erb</strong></p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<div class='box'>
<%= yield %>
</div>
</pre>
</div>
<p>Note that the partial layout has access to the local <code>article</code> variable that was passed into the <code>render</code> call. However, unlike application-wide layouts, partial layouts still have the underscore prefix.</p><p>You can also render a block of code within a partial layout instead of calling <code>yield</code>. For example, if we didn't have the <code>_article</code> partial, we could do this instead:</p><p><strong>articles/show.html.erb</strong></p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<% render(layout: 'box', locals: { article: @article }) do %>
<div>
<p><%= article.body %></p>
</div>
<% end %>
</pre>
</div>
<p>Supposing we use the same <code>_box</code> partial from above, this would produce the same output as the previous example.</p><h3 id="view-paths"><a class="anchorlink" href="#view-paths">5 View Paths</a></h3><p>When rendering a response, the controller needs to resolve where the different
views are located. By default it only looks inside the <code>app/views</code> directory.</p><p>We can add other locations and give them a certain precedence when resolving
paths using the <code>prepend_view_path</code> and <code>append_view_path</code> methods.</p><h4 id="prepend-view-path"><a class="anchorlink" href="#prepend-view-path">5.1 Prepend view path</a></h4><p>This can be helpful for example, when we want to put views inside a different
directory for subdomains.</p><p>We can do this by using:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
prepend_view_path "app/views/#{request.subdomain}"
</pre>
</div>
<p>Then Action View will look first in this directory when resolving views.</p><h4 id="append-view-path"><a class="anchorlink" href="#append-view-path">5.2 Append view path</a></h4><p>Similarly, we can append paths:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
append_view_path "app/views/direct"
</pre>
</div>
<p>This will add <code>app/views/direct</code> to the end of the lookup paths.</p><h3 id="overview-of-helpers-provided-by-action-view"><a class="anchorlink" href="#overview-of-helpers-provided-by-action-view">6 Overview of helpers provided by Action View</a></h3><p>WIP: Not all the helpers are listed here. For a full list see the <a href="http://edgeapi.rubyonrails.org/classes/ActionView/Helpers.html">API documentation</a></p><p>The following is only a brief overview summary of the helpers available in Action View. It's recommended that you review the <a href="http://edgeapi.rubyonrails.org/classes/ActionView/Helpers.html">API Documentation</a>, which covers all of the helpers in more detail, but this should serve as a good starting point.</p><h4 id="assettaghelper"><a class="anchorlink" href="#assettaghelper">6.1 AssetTagHelper</a></h4><p>This module provides methods for generating HTML that links views to assets such as images, JavaScript files, stylesheets, and feeds.</p><p>By default, Rails links to these assets on the current host in the public folder, but you can direct Rails to link to assets from a dedicated assets server by setting <code>config.action_controller.asset_host</code> in the application configuration, typically in <code>config/environments/production.rb</code>. For example, let's say your asset host is <code>assets.example.com</code>:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
config.action_controller.asset_host = "assets.example.com"
image_tag("rails.png") # => <img src="http://assets.example.com/images/rails.png" />
</pre>
</div>
<h5 id="auto-discovery-link-tag"><a class="anchorlink" href="#auto-discovery-link-tag">6.1.1 auto_discovery_link_tag</a></h5><p>Returns a link tag that browsers and feed readers can use to auto-detect an RSS, Atom, or JSON feed.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
auto_discovery_link_tag(:rss, "http://www.example.com/feed.rss", { title: "RSS Feed" }) # =>
<link rel="alternate" type="application/rss+xml" title="RSS Feed" href="http://www.example.com/feed.rss" />
</pre>
</div>
<h5 id="image-path"><a class="anchorlink" href="#image-path">6.1.2 image_path</a></h5><p>Computes the path to an image asset in the <code>app/assets/images</code> directory. Full paths from the document root will be passed through. Used internally by <code>image_tag</code> to build the image path.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
image_path("edit.png") # => /assets/edit.png
</pre>
</div>
<p>Fingerprint will be added to the filename if config.assets.digest is set to true.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
image_path("edit.png") # => /assets/edit-2d1a2db63fc738690021fedb5a65b68e.png
</pre>
</div>
<h5 id="image-url"><a class="anchorlink" href="#image-url">6.1.3 image_url</a></h5><p>Computes the URL to an image asset in the <code>app/assets/images</code> directory. This will call <code>image_path</code> internally and merge with your current host or your asset host.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
image_url("edit.png") # => http://www.example.com/assets/edit.png
</pre>
</div>
<h5 id="image-tag"><a class="anchorlink" href="#image-tag">6.1.4 image_tag</a></h5><p>Returns an HTML image tag for the source. The source can be a full path or a file that exists in your <code>app/assets/images</code> directory.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
image_tag("icon.png") # => <img src="/assets/icon.png" />
</pre>
</div>
<h5 id="javascript-include-tag"><a class="anchorlink" href="#javascript-include-tag">6.1.5 javascript_include_tag</a></h5><p>Returns an HTML script tag for each of the sources provided. You can pass in the filename (<code>.js</code> extension is optional) of JavaScript files that exist in your <code>app/assets/javascripts</code> directory for inclusion into the current page or you can pass the full path relative to your document root.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
javascript_include_tag "common" # => <script src="/assets/common.js"></script>
</pre>
</div>
<h5 id="javascript-path"><a class="anchorlink" href="#javascript-path">6.1.6 javascript_path</a></h5><p>Computes the path to a JavaScript asset in the <code>app/assets/javascripts</code> directory. If the source filename has no extension, <code>.js</code> will be appended. Full paths from the document root will be passed through. Used internally by <code>javascript_include_tag</code> to build the script path.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
javascript_path "common" # => /assets/common.js
</pre>
</div>
<h5 id="javascript-url"><a class="anchorlink" href="#javascript-url">6.1.7 javascript_url</a></h5><p>Computes the URL to a JavaScript asset in the <code>app/assets/javascripts</code> directory. This will call <code>javascript_path</code> internally and merge with your current host or your asset host.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
javascript_url "common" # => http://www.example.com/assets/common.js
</pre>
</div>
<h5 id="stylesheet-link-tag"><a class="anchorlink" href="#stylesheet-link-tag">6.1.8 stylesheet_link_tag</a></h5><p>Returns a stylesheet link tag for the sources specified as arguments. If you don't specify an extension, <code>.css</code> will be appended automatically.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
stylesheet_link_tag "application" # => <link href="/assets/application.css" media="screen" rel="stylesheet" />
</pre>
</div>
<h5 id="stylesheet-path"><a class="anchorlink" href="#stylesheet-path">6.1.9 stylesheet_path</a></h5><p>Computes the path to a stylesheet asset in the <code>app/assets/stylesheets</code> directory. If the source filename has no extension, <code>.css</code> will be appended. Full paths from the document root will be passed through. Used internally by <code>stylesheet_link_tag</code> to build the stylesheet path.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
stylesheet_path "application" # => /assets/application.css
</pre>
</div>
<h5 id="stylesheet-url"><a class="anchorlink" href="#stylesheet-url">6.1.10 stylesheet_url</a></h5><p>Computes the URL to a stylesheet asset in the <code>app/assets/stylesheets</code> directory. This will call <code>stylesheet_path</code> internally and merge with your current host or your asset host.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
stylesheet_url "application" # => http://www.example.com/assets/application.css
</pre>
</div>
<h4 id="atomfeedhelper"><a class="anchorlink" href="#atomfeedhelper">6.2 AtomFeedHelper</a></h4><h5 id="atom-feed"><a class="anchorlink" href="#atom-feed">6.2.1 atom_feed</a></h5><p>This helper makes building an Atom feed easy. Here's a full usage example:</p><p><strong>config/routes.rb</strong></p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
resources :articles
</pre>
</div>
<p><strong>app/controllers/articles_controller.rb</strong></p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
def index
@articles = Article.all
respond_to do |format|
format.html
format.atom
end
end
</pre>
</div>
<p><strong>app/views/articles/index.atom.builder</strong></p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
atom_feed do |feed|
feed.title("Articles Index")
feed.updated(@articles.first.created_at)
@articles.each do |article|
feed.entry(article) do |entry|
entry.title(article.title)
entry.content(article.body, type: 'html')
entry.author do |author|
author.name(article.author_name)
end
end
end
end
</pre>
</div>
<h4 id="benchmarkhelper"><a class="anchorlink" href="#benchmarkhelper">6.3 BenchmarkHelper</a></h4><h5 id="benchmark"><a class="anchorlink" href="#benchmark">6.3.1 benchmark</a></h5><p>Allows you to measure the execution time of a block in a template and records the result to the log. Wrap this block around expensive operations or possible bottlenecks to get a time reading for the operation.</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<% benchmark "Process data files" do %>
<%= expensive_files_operation %>
<% end %>
</pre>
</div>
<p>This would add something like "Process data files (0.34523)" to the log, which you can then use to compare timings when optimizing your code.</p><h4 id="cachehelper"><a class="anchorlink" href="#cachehelper">6.4 CacheHelper</a></h4><h5 id="cache"><a class="anchorlink" href="#cache">6.4.1 cache</a></h5><p>A method for caching fragments of a view rather than an entire action or page. This technique is useful for caching pieces like menus, lists of news topics, static HTML fragments, and so on. This method takes a block that contains the content you wish to cache. See <code>AbstractController::Caching::Fragments</code> for more information.</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<% cache do %>
<%= render "shared/footer" %>
<% end %>
</pre>
</div>
<h4 id="capturehelper"><a class="anchorlink" href="#capturehelper">6.5 CaptureHelper</a></h4><h5 id="capture"><a class="anchorlink" href="#capture">6.5.1 capture</a></h5><p>The <code>capture</code> method allows you to extract part of a template into a variable. You can then use this variable anywhere in your templates or layout.</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<% @greeting = capture do %>
<p>Welcome! The date and time is <%= Time.now %></p>
<% end %>
</pre>
</div>
<p>The captured variable can then be used anywhere else.</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<html>
<head>
<title>Welcome!</title>
</head>
<body>
<%= @greeting %>
</body>
</html>
</pre>
</div>
<h5 id="content-for"><a class="anchorlink" href="#content-for">6.5.2 content_for</a></h5><p>Calling <code>content_for</code> stores a block of markup in an identifier for later use. You can make subsequent calls to the stored content in other templates or the layout by passing the identifier as an argument to <code>yield</code>.</p><p>For example, let's say we have a standard application layout, but also a special page that requires certain JavaScript that the rest of the site doesn't need. We can use <code>content_for</code> to include this JavaScript on our special page without fattening up the rest of the site.</p><p><strong>app/views/layouts/application.html.erb</strong></p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<html>
<head>
<title>Welcome!</title>
<%= yield :special_script %>
</head>
<body>
<p>Welcome! The date and time is <%= Time.now %></p>
</body>
</html>
</pre>
</div>
<p><strong>app/views/articles/special.html.erb</strong></p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<p>This is a special page.</p>
<% content_for :special_script do %>
<script>alert('Hello!')</script>
<% end %>
</pre>
</div>
<h4 id="datehelper"><a class="anchorlink" href="#datehelper">6.6 DateHelper</a></h4><h5 id="date-select"><a class="anchorlink" href="#date-select">6.6.1 date_select</a></h5><p>Returns a set of select tags (one for year, month, and day) pre-selected for accessing a specified date-based attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
date_select("article", "published_on")
</pre>
</div>
<h5 id="datetime-select"><a class="anchorlink" href="#datetime-select">6.6.2 datetime_select</a></h5><p>Returns a set of select tags (one for year, month, day, hour, and minute) pre-selected for accessing a specified datetime-based attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
datetime_select("article", "published_on")
</pre>
</div>
<h5 id="distance-of-time-in-words"><a class="anchorlink" href="#distance-of-time-in-words">6.6.3 distance_of_time_in_words</a></h5><p>Reports the approximate distance in time between two Time or Date objects or integers as seconds. Set <code>include_seconds</code> to true if you want more detailed approximations.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
distance_of_time_in_words(Time.now, Time.now + 15.seconds) # => less than a minute
distance_of_time_in_words(Time.now, Time.now + 15.seconds, include_seconds: true) # => less than 20 seconds
</pre>
</div>
<h5 id="select-date"><a class="anchorlink" href="#select-date">6.6.4 select_date</a></h5><p>Returns a set of HTML select-tags (one for year, month, and day) pre-selected with the <code>date</code> provided.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a date select that defaults to the date provided (six days after today)
select_date(Time.today + 6.days)
# Generates a date select that defaults to today (no specified date)
select_date()
</pre>
</div>
<h5 id="select-datetime"><a class="anchorlink" href="#select-datetime">6.6.5 select_datetime</a></h5><p>Returns a set of HTML select-tags (one for year, month, day, hour, and minute) pre-selected with the <code>datetime</code> provided.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a datetime select that defaults to the datetime provided (four days after today)
select_datetime(Time.now + 4.days)
# Generates a datetime select that defaults to today (no specified datetime)
select_datetime()
</pre>
</div>
<h5 id="select-day"><a class="anchorlink" href="#select-day">6.6.6 select_day</a></h5><p>Returns a select tag with options for each of the days 1 through 31 with the current day selected.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a select field for days that defaults to the day for the date provided
select_day(Time.today + 2.days)
# Generates a select field for days that defaults to the number given
select_day(5)
</pre>
</div>
<h5 id="select-hour"><a class="anchorlink" href="#select-hour">6.6.7 select_hour</a></h5><p>Returns a select tag with options for each of the hours 0 through 23 with the current hour selected.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a select field for hours that defaults to the hours for the time provided
select_hour(Time.now + 6.hours)
</pre>
</div>
<h5 id="select-minute"><a class="anchorlink" href="#select-minute">6.6.8 select_minute</a></h5><p>Returns a select tag with options for each of the minutes 0 through 59 with the current minute selected.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a select field for minutes that defaults to the minutes for the time provided.
select_minute(Time.now + 10.minutes)
</pre>
</div>
<h5 id="select-month"><a class="anchorlink" href="#select-month">6.6.9 select_month</a></h5><p>Returns a select tag with options for each of the months January through December with the current month selected.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a select field for months that defaults to the current month
select_month(Date.today)
</pre>
</div>
<h5 id="select-second"><a class="anchorlink" href="#select-second">6.6.10 select_second</a></h5><p>Returns a select tag with options for each of the seconds 0 through 59 with the current second selected.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a select field for seconds that defaults to the seconds for the time provided
select_second(Time.now + 16.seconds)
</pre>
</div>
<h5 id="select-time"><a class="anchorlink" href="#select-time">6.6.11 select_time</a></h5><p>Returns a set of HTML select-tags (one for hour and minute).</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a time select that defaults to the time provided
select_time(Time.now)
</pre>
</div>
<h5 id="select-year"><a class="anchorlink" href="#select-year">6.6.12 select_year</a></h5><p>Returns a select tag with options for each of the five years on each side of the current, which is selected. The five year radius can be changed using the <code>:start_year</code> and <code>:end_year</code> keys in the <code>options</code>.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Generates a select field for five years on either side of Date.today that defaults to the current year
select_year(Date.today)
# Generates a select field from 1900 to 2009 that defaults to the current year
select_year(Date.today, start_year: 1900, end_year: 2009)
</pre>
</div>
<h5 id="time-ago-in-words"><a class="anchorlink" href="#time-ago-in-words">6.6.13 time_ago_in_words</a></h5><p>Like <code>distance_of_time_in_words</code>, but where <code>to_time</code> is fixed to <code>Time.now</code>.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
time_ago_in_words(3.minutes.from_now) # => 3 minutes
</pre>
</div>
<h5 id="time-select"><a class="anchorlink" href="#time-select">6.6.14 time_select</a></h5><p>Returns a set of select tags (one for hour, minute, and optionally second) pre-selected for accessing a specified time-based attribute. The selects are prepared for multi-parameter assignment to an Active Record object.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Creates a time select tag that, when POSTed, will be stored in the order variable in the submitted attribute
time_select("order", "submitted")
</pre>
</div>
<h4 id="debughelper"><a class="anchorlink" href="#debughelper">6.7 DebugHelper</a></h4><p>Returns a <code>pre</code> tag that has object dumped by YAML. This creates a very readable way to inspect an object.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
my_hash = { 'first' => 1, 'second' => 'two', 'third' => [1,2,3] }
debug(my_hash)
</pre>
</div>
<div class="code_container">
<pre class="brush: xml; gutter: false; toolbar: false">
<pre class='debug_dump'>---
first: 1
second: two
third:
- 1
- 2
- 3
</pre>
</pre>
</div>
<h4 id="formhelper"><a class="anchorlink" href="#formhelper">6.8 FormHelper</a></h4><p>Form helpers are designed to make working with models much easier compared to using just standard HTML elements by providing a set of methods for creating forms based on your models. This helper generates the HTML for forms, providing a method for each sort of input (e.g., text, password, select, and so on). When the form is submitted (i.e., when the user hits the submit button or form.submit is called via JavaScript), the form inputs will be bundled into the params object and passed back to the controller.</p><p>There are two types of form helpers: those that specifically work with model attributes and those that don't. This helper deals with those that work with model attributes; to see an example of form helpers that don't work with model attributes, check the <code>ActionView::Helpers::FormTagHelper</code> documentation.</p><p>The core method of this helper, <code>form_for</code>, gives you the ability to create a form for a model instance; for example, let's say that you have a model Person and want to create a new instance of it:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
# Note: a @person variable will have been created in the controller (e.g. @person = Person.new)
<%= form_for @person, url: { action: "create" } do |f| %>
<%= f.text_field :first_name %>
<%= f.text_field :last_name %>
<%= submit_tag 'Create' %>
<% end %>
</pre>
</div>
<p>The HTML generated for this would be:</p><div class="code_container">
<pre class="brush: xml; gutter: false; toolbar: false">
<form class="new_person" id="new_person" action="/people" accept-charset="UTF-8" method="post">
<input name="utf8" type="hidden" value="&#x2713;" />
<input type="hidden" name="authenticity_token" value="lTuvBzs7ANygT0NFinXj98tfw3Emfm65wwYLbUvoWsK2pngccIQSUorM2C035M9dZswXgWTvKwFS8W5TVblpYw==" />
<input type="text" name="person[first_name]" id="person_first_name" />
<input type="text" name="person[last_name]" id="person_last_name" />
<input type="submit" name="commit" value="Create" data-disable-with="Create" />
</form>
</pre>
</div>
<p>The params object created when this form is submitted would look like:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
{"utf8" => "✓", "authenticity_token" => "lTuvBzs7ANygT0NFinXj98tfw3Emfm65wwYLbUvoWsK2pngccIQSUorM2C035M9dZswXgWTvKwFS8W5TVblpYw==", "person" => {"first_name" => "William", "last_name" => "Smith"}, "commit" => "Create", "controller" => "people", "action" => "create"}
</pre>
</div>
<p>The params hash has a nested person value, which can therefore be accessed with <code>params[:person]</code> in the controller.</p><h5 id="check-box"><a class="anchorlink" href="#check-box">6.8.1 check_box</a></h5><p>Returns a checkbox tag tailored for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Let's say that @article.validated? is 1:
check_box("article", "validated")
# => <input type="checkbox" id="article_validated" name="article[validated]" value="1" />
# <input name="article[validated]" type="hidden" value="0" />
</pre>
</div>
<h5 id="fields-for"><a class="anchorlink" href="#fields-for">6.8.2 fields_for</a></h5><p>Creates a scope around a specific model object like <code>form_for</code>, but doesn't create the form tags themselves. This makes <code>fields_for</code> suitable for specifying additional model objects in the same form:</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= form_for @person, url: { action: "update" } do |person_form| %>
First name: <%= person_form.text_field :first_name %>
Last name : <%= person_form.text_field :last_name %>
<%= fields_for @person.permission do |permission_fields| %>
Admin? : <%= permission_fields.check_box :admin %>
<% end %>
<% end %>
</pre>
</div>
<h5 id="file-field"><a class="anchorlink" href="#file-field">6.8.3 file_field</a></h5><p>Returns a file upload input tag tailored for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
file_field(:user, :avatar)
# => <input type="file" id="user_avatar" name="user[avatar]" />
</pre>
</div>
<h5 id="form-for"><a class="anchorlink" href="#form-for">6.8.4 form_for</a></h5><p>Creates a form and a scope around a specific model object that is used as a base for questioning about values for the fields.</p><div class="code_container">
<pre class="brush: ruby; html-script: true; gutter: false; toolbar: false">
<%= form_for @article do |f| %>
<%= f.label :title, 'Title' %>:
<%= f.text_field :title %><br>
<%= f.label :body, 'Body' %>:
<%= f.text_area :body %><br>
<% end %>
</pre>
</div>
<h5 id="hidden-field"><a class="anchorlink" href="#hidden-field">6.8.5 hidden_field</a></h5><p>Returns a hidden input tag tailored for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
hidden_field(:user, :token)
# => <input type="hidden" id="user_token" name="user[token]" value="#{@user.token}" />
</pre>
</div>
<h5 id="label"><a class="anchorlink" href="#label">6.8.6 label</a></h5><p>Returns a label tag tailored for labelling an input field for a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
label(:article, :title)
# => <label for="article_title">Title</label>
</pre>
</div>
<h5 id="password-field"><a class="anchorlink" href="#password-field">6.8.7 password_field</a></h5><p>Returns an input tag of the "password" type tailored for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
password_field(:login, :pass)
# => <input type="text" id="login_pass" name="login[pass]" value="#{@login.pass}" />
</pre>
</div>
<h5 id="radio-button"><a class="anchorlink" href="#radio-button">6.8.8 radio_button</a></h5><p>Returns a radio button tag for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
# Let's say that @article.category returns "rails":
radio_button("article", "category", "rails")
radio_button("article", "category", "java")
# => <input type="radio" id="article_category_rails" name="article[category]" value="rails" checked="checked" />
# <input type="radio" id="article_category_java" name="article[category]" value="java" />
</pre>
</div>
<h5 id="text-area"><a class="anchorlink" href="#text-area">6.8.9 text_area</a></h5><p>Returns a textarea opening and closing tag set tailored for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
text_area(:comment, :text, size: "20x30")
# => <textarea cols="20" rows="30" id="comment_text" name="comment[text]">
# #{@comment.text}
# </textarea>
</pre>
</div>
<h5 id="text-field"><a class="anchorlink" href="#text-field">6.8.10 text_field</a></h5><p>Returns an input tag of the "text" type tailored for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
text_field(:article, :title)
# => <input type="text" id="article_title" name="article[title]" value="#{@article.title}" />
</pre>
</div>
<h5 id="email-field"><a class="anchorlink" href="#email-field">6.8.11 email_field</a></h5><p>Returns an input tag of the "email" type tailored for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
email_field(:user, :email)
# => <input type="email" id="user_email" name="user[email]" value="#{@user.email}" />
</pre>
</div>
<h5 id="url-field"><a class="anchorlink" href="#url-field">6.8.12 url_field</a></h5><p>Returns an input tag of the "url" type tailored for accessing a specified attribute.</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
url_field(:user, :url)
# => <input type="url" id="user_url" name="user[url]" value="#{@user.url}" />
</pre>
</div>
<h4 id="formoptionshelper"><a class="anchorlink" href="#formoptionshelper">6.9 FormOptionsHelper</a></h4><p>Provides a number of methods for turning different kinds of containers into a set of option tags.</p><h5 id="collection-select"><a class="anchorlink" href="#collection-select">6.9.1 collection_select</a></h5><p>Returns <code>select</code> and <code>option</code> tags for the collection of existing return values of <code>method</code> for <code>object</code>'s class.</p><p>Example object structure for use with this method:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
class Article < ApplicationRecord
belongs_to :author
end
class Author < ApplicationRecord
has_many :articles
def name_with_initial
"#{first_name.first}. #{last_name}"
end
end
</pre>
</div>
<p>Sample usage (selecting the associated Author for an instance of Article, <code>@article</code>):</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
collection_select(:article, :author_id, Author.all, :id, :name_with_initial, { prompt: true })
</pre>
</div>
<p>If <code>@article.author_id</code> is 1, this would return:</p><div class="code_container">
<pre class="brush: xml; gutter: false; toolbar: false">
<select name="article[author_id]">
<option value="">Please select</option>
<option value="1" selected="selected">D. Heinemeier Hansson</option>
<option value="2">D. Thomas</option>
<option value="3">M. Clark</option>
</select>
</pre>
</div>
<h5 id="collection-radio-buttons"><a class="anchorlink" href="#collection-radio-buttons">6.9.2 collection_radio_buttons</a></h5><p>Returns <code>radio_button</code> tags for the collection of existing return values of <code>method</code> for <code>object</code>'s class.</p><p>Example object structure for use with this method:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
class Article < ApplicationRecord
belongs_to :author
end
class Author < ApplicationRecord
has_many :articles
def name_with_initial
"#{first_name.first}. #{last_name}"
end
end
</pre>
</div>
<p>Sample usage (selecting the associated Author for an instance of Article, <code>@article</code>):</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
collection_radio_buttons(:article, :author_id, Author.all, :id, :name_with_initial)
</pre>
</div>
<p>If <code>@article.author_id</code> is 1, this would return:</p><div class="code_container">
<pre class="brush: xml; gutter: false; toolbar: false">
<input id="article_author_id_1" name="article[author_id]" type="radio" value="1" checked="checked" />
<label for="article_author_id_1">D. Heinemeier Hansson</label>
<input id="article_author_id_2" name="article[author_id]" type="radio" value="2" />
<label for="article_author_id_2">D. Thomas</label>
<input id="article_author_id_3" name="article[author_id]" type="radio" value="3" />
<label for="article_author_id_3">M. Clark</label>
</pre>
</div>
<h5 id="collection-check-boxes"><a class="anchorlink" href="#collection-check-boxes">6.9.3 collection_check_boxes</a></h5><p>Returns <code>check_box</code> tags for the collection of existing return values of <code>method</code> for <code>object</code>'s class.</p><p>Example object structure for use with this method:</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
class Article < ApplicationRecord
has_and_belongs_to_many :authors
end
class Author < ApplicationRecord
has_and_belongs_to_many :articles
def name_with_initial
"#{first_name.first}. #{last_name}"
end
end
</pre>
</div>
<p>Sample usage (selecting the associated Authors for an instance of Article, <code>@article</code>):</p><div class="code_container">
<pre class="brush: ruby; gutter: false; toolbar: false">
collection_check_boxes(:article, :author_ids, Author.all, :id, :name_with_initial)
</pre>
</div>
<p>If <code>@article.author_ids</code> is [1], this would return:</p><div class="code_container">