View source for Rails 3 View

Helpers are intended to generate complicated markup for use in the associated views.

== Layouts ==
* The default layout for the entire application is <code>app/views/layouts/application.html.erb</code>.  
* If controller-specific layouts are found, they are used instead.
* You can use the layout directive at the class level in any controller (that is, not inside an action) to set the layout for the entire controller: 
<source lang="ruby">
layout 'my_layout'
</source>
* You can include a layout for a specific action with an explicit call to render inside the action: 
<source lang="ruby">
render :layout => 'my_layout'
</source>
* Sometimes, you want to render an action without a layout. In that case, you can pass false in place of the layout name: 
<source lang="ruby">
render :layout => false
</source>

=== Form Example ===
<source lang="ruby">
<%= form_for(@article) do |f| %> 
<% if @article.errors.any? %> 
<div id="errorExplanation"> 
<h2><%= pluralize(@article.errors.count, "error") %>
prohibited this article from being saved:</h2> 
<ul> 
<% @article.errors.full_messages.each do |msg| %> 
<li><%= msg %></li> 
<% end %> 
</ul> 
</div> 
<% end %>

<div class="field"> 
<%= f.label :title %><br /> 
<%= f.text_field :title %> 
</div>
<div class="field"> 
<%= f.label :location %><br /> 
<%= f.text_field :location %> 
</div> 
<div class="field"> 
<%= f.label :excerpt %><br /> 
<%= f.text_field :excerpt %> 
</div> 
<div class="field"> 
<%= f.label :body %><br /> 
<%= f.text_area :body %> 
</div> 
<div class="field"> 
<%= f.label :published_at %><br /> 
<%= f.datetime_select :published_at %> 
</div> 
<div class="actions"> 
<%= f.submit %> 
</div> 
<% end %>
</source>

Parameters are sent to the controller in <code>params[:article]</code>.

=== Partials ===
<source lang="ruby">
<%= render 'form' %>
</source>
renders <code>app/views/articles/_form.html.erb</code>
<source lang="ruby">
<%= render 'header', :title => 'My Blog' %>
</source>
renders <code>app/views/articles/_header.html.erb</code> and passes local variable <code>title</code>
<source lang="ruby">
<%= render @article %>
</source>
Rails looks for a partial in <code>app/views/articles/_article.html.erb</code> and automatically assigns a local variable called article. It's a shortcut for
<source lang="ruby">
<%= render 'article', :article => @article %>
</source>
<source lang="ruby">
<%= render @articles %>
</source>
equivalent to 
<source lang="ruby">
<% @articles.each do |object| %> 
<%= render object %> 
<% end %>
</source>