227 lines
8.9 KiB
Ruby
227 lines
8.9 KiB
Ruby
require 'active_support/core_ext/object/blank'
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module ActionView
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# = Action View Partials
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#
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# There's also a convenience method for rendering sub templates within the current controller that depends on a
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# single object (we call this kind of sub templates for partials). It relies on the fact that partials should
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# follow the naming convention of being prefixed with an underscore -- as to separate them from regular
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# templates that could be rendered on their own.
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#
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# In a template for Advertiser#account:
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#
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# <%= render :partial => "account" %>
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#
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# This would render "advertiser/_account.erb" and pass the instance variable @account in as a local variable
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# +account+ to the template for display.
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#
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# In another template for Advertiser#buy, we could have:
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#
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# <%= render :partial => "account", :locals => { :account => @buyer } %>
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#
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# <% for ad in @advertisements %>
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# <%= render :partial => "ad", :locals => { :ad => ad } %>
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# <% end %>
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#
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# This would first render "advertiser/_account.erb" with @buyer passed in as the local variable +account+, then
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# render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display.
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#
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# == The :as and :object options
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#
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# By default <tt>ActionView::Partials::PartialRenderer</tt> has its object in a local variable with the same
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# name as the template. So, given
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#
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# <%= render :partial => "contract" %>
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#
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# within contract we'll get <tt>@contract</tt> in the local variable +contract+, as if we had written
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#
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# <%= render :partial => "contract", :locals => { :contract => @contract } %>
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#
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# With the <tt>:as</tt> option we can specify a different name for said local variable. For example, if we
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# wanted it to be +agreement+ instead of +contract+ we'd do:
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#
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# <%= render :partial => "contract", :as => :agreement %>
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#
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# The <tt>:object</tt> option can be used to directly specify which object is rendered into the partial;
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# useful when the template's object is elsewhere, in a different ivar or in a local variable for instance.
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#
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# Revisiting a previous example we could have written this code:
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#
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# <%= render :partial => "account", :object => @buyer %>
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#
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# <% for ad in @advertisements %>
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# <%= render :partial => "ad", :object => ad %>
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# <% end %>
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#
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# The <tt>:object</tt> and <tt>:as</tt> options can be used together.
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#
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# == Rendering a collection of partials
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#
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# The example of partial use describes a familiar pattern where a template needs to iterate over an array and
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# render a sub template for each of the elements. This pattern has been implemented as a single method that
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# accepts an array and renders a partial by the same name as the elements contained within. So the three-lined
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# example in "Using partials" can be rewritten with a single line:
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#
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# <%= render :partial => "ad", :collection => @advertisements %>
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#
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# This will render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display. An
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# iteration counter will automatically be made available to the template with a name of the form
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# +partial_name_counter+. In the case of the example above, the template would be fed +ad_counter+.
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#
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# The <tt>:as</tt> option may be used when rendering partials.
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#
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# You can specify a partial to be rendered between elements via the <tt>:spacer_template</tt> option.
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# The following example will render <tt>advertiser/_ad_divider.html.erb</tt> between each ad partial:
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#
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# <%= render :partial => "ad", :collection => @advertisements, :spacer_template => "ad_divider" %>
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#
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# If the given <tt>:collection</tt> is nil or empty, <tt>render</tt> will return nil. This will allow you
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# to specify a text which will displayed instead by using this form:
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#
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# <%= render(:partial => "ad", :collection => @advertisements) || "There's no ad to be displayed" %>
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#
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# NOTE: Due to backwards compatibility concerns, the collection can't be one of hashes. Normally you'd also
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# just keep domain objects, like Active Records, in there.
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#
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# == Rendering shared partials
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#
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# Two controllers can share a set of partials and render them like this:
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#
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# <%= render :partial => "advertisement/ad", :locals => { :ad => @advertisement } %>
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#
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# This will render the partial "advertisement/_ad.erb" regardless of which controller this is being called from.
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#
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# == Rendering objects with the RecordIdentifier
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#
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# Instead of explicitly naming the location of a partial, you can also let the RecordIdentifier do the work if
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# you're following its conventions for RecordIdentifier#partial_path. Examples:
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#
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# # @account is an Account instance, so it uses the RecordIdentifier to replace
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# # <%= render :partial => "accounts/account", :locals => { :account => @account} %>
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# <%= render :partial => @account %>
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#
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# # @posts is an array of Post instances, so it uses the RecordIdentifier to replace
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# # <%= render :partial => "posts/post", :collection => @posts %>
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# <%= render :partial => @posts %>
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#
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# == Rendering the default case
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#
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# If you're not going to be using any of the options like collections or layouts, you can also use the short-hand
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# defaults of render to render partials. Examples:
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#
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# # Instead of <%= render :partial => "account" %>
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# <%= render "account" %>
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#
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# # Instead of <%= render :partial => "account", :locals => { :account => @buyer } %>
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# <%= render "account", :account => @buyer %>
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#
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# # @account is an Account instance, so it uses the RecordIdentifier to replace
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# # <%= render :partial => "accounts/account", :locals => { :account => @account } %>
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# <%= render(@account) %>
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#
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# # @posts is an array of Post instances, so it uses the RecordIdentifier to replace
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# # <%= render :partial => "posts/post", :collection => @posts %>
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# <%= render(@posts) %>
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#
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# == Rendering partials with layouts
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#
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# Partials can have their own layouts applied to them. These layouts are different than the ones that are
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# specified globally for the entire action, but they work in a similar fashion. Imagine a list with two types
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# of users:
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#
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# <%# app/views/users/index.html.erb &>
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# Here's the administrator:
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# <%= render :partial => "user", :layout => "administrator", :locals => { :user => administrator } %>
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#
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# Here's the editor:
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# <%= render :partial => "user", :layout => "editor", :locals => { :user => editor } %>
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#
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# <%# app/views/users/_user.html.erb &>
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# Name: <%= user.name %>
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#
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# <%# app/views/users/_administrator.html.erb &>
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# <div id="administrator">
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# Budget: $<%= user.budget %>
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# <%= yield %>
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# </div>
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#
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# <%# app/views/users/_editor.html.erb &>
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# <div id="editor">
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# Deadline: <%= user.deadline %>
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# <%= yield %>
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# </div>
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#
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# ...this will return:
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#
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# Here's the administrator:
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# <div id="administrator">
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# Budget: $<%= user.budget %>
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# Name: <%= user.name %>
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# </div>
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#
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# Here's the editor:
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# <div id="editor">
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# Deadline: <%= user.deadline %>
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# Name: <%= user.name %>
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# </div>
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#
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# You can also apply a layout to a block within any template:
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#
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# <%# app/views/users/_chief.html.erb &>
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# <%= render(:layout => "administrator", :locals => { :user => chief }) do %>
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# Title: <%= chief.title %>
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# <% end %>
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#
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# ...this will return:
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#
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# <div id="administrator">
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# Budget: $<%= user.budget %>
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# Title: <%= chief.name %>
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# </div>
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#
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# As you can see, the <tt>:locals</tt> hash is shared between both the partial and its layout.
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#
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# If you pass arguments to "yield" then this will be passed to the block. One way to use this is to pass
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# an array to layout and treat it as an enumerable.
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#
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# <%# app/views/users/_user.html.erb &>
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# <div class="user">
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# Budget: $<%= user.budget %>
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# <%= yield user %>
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# </div>
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#
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# <%# app/views/users/index.html.erb &>
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# <%= render :layout => @users do |user| %>
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# Title: <%= user.title %>
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# <% end %>
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#
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# This will render the layout for each user and yield to the block, passing the user, each time.
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#
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# You can also yield multiple times in one layout and use block arguments to differentiate the sections.
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#
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# <%# app/views/users/_user.html.erb &>
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# <div class="user">
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# <%= yield user, :header %>
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# Budget: $<%= user.budget %>
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# <%= yield user, :footer %>
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# </div>
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#
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# <%# app/views/users/index.html.erb &>
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# <%= render :layout => @users do |user, section| %>
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# <%- case section when :header -%>
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# Title: <%= user.title %>
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# <%- when :footer -%>
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# Deadline: <%= user.deadline %>
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# <%- end -%>
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# <% end %>
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module Partials
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def _render_partial(options, &block) #:nodoc:
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_partial_renderer.setup(options, block).render
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end
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def _partial_renderer #:nodoc:
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@_partial_renderer ||= PartialRenderer.new(self)
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end
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end
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end
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