module ActionView
# 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.erb" and pass the instance variable @account in as a local variable
# +account+ to the template for display.
#
# In another template for Advertiser#buy, we could have:
#
# <%= render :partial => "account", :locals => { :account => @buyer } %>
#
# <% for ad in @advertisements %>
# <%= render :partial => "ad", :locals => { :ad => ad } %>
# <% end %>
#
# This would first render "advertiser/_account.erb" with @buyer passed in as the local variable +account+, then
# render "advertiser/_ad.erb" and pass the local variable +ad+ to the template for display.
#
# == 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.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+.
#
# 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.erb" regardless of which controller this is being called from.
#
# == 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>
#
# 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: $<%= user.budget %>
# <%= yield user, :footer %>
# </div>
#
# <%# app/views/users/index.html.erb &>
# <% render :layout => @users do |user, section| %>
# <%- case section when :header -%>
# Title: <%= user.title %>
# <%- when :footer -%>
# Deadline: <%= user.deadline %>
# <%- end -%>
# <% end %>
module Partials
extend ActiveSupport::Memoizable
private
def render_partial(options = {}) #:nodoc:
local_assigns = options[:locals] || {}
case partial_path = options[:partial]
when String, Symbol, NilClass
if options.has_key?(:collection)
render_partial_collection(options)
else
_pick_partial_template(partial_path).render_partial(self, options[:object], local_assigns)
end
when ActionView::Helpers::FormBuilder
builder_partial_path = partial_path.class.to_s.demodulize.underscore.sub(/_builder$/, '')
local_assigns.merge!(builder_partial_path.to_sym => partial_path)
render_partial(:partial => builder_partial_path, :object => options[:object], :locals => local_assigns)
when Array, ActiveRecord::Associations::AssociationCollection, ActiveRecord::NamedScope::Scope
render_partial_collection(options.except(:partial).merge(:collection => partial_path))
else
object = partial_path
render_partial(
:partial => ActionController::RecordIdentifier.partial_path(object, controller.class.controller_path),
:object => object,
:locals => local_assigns
)
end
end
def render_partial_collection(options = {}) #:nodoc:
return nil if options[:collection].blank?
partial = options[:partial]
spacer = options[:spacer_template] ? render(:partial => options[:spacer_template]) : ''
local_assigns = options[:locals] ? options[:locals].clone : {}
as = options[:as]
index = 0
options[:collection].map do |object|
_partial_path ||= partial ||
ActionController::RecordIdentifier.partial_path(object, controller.class.controller_path)
template = _pick_partial_template(_partial_path)
local_assigns[template.counter_name] = index
result = template.render_partial(self, object, local_assigns, as)
index += 1
result
end.join(spacer)
end
def _pick_partial_template(partial_path) #:nodoc:
if partial_path.include?('/')
path = File.join(File.dirname(partial_path), "_#{File.basename(partial_path)}")
elsif controller
path = "#{controller.class.controller_path}/_#{partial_path}"
else
path = "_#{partial_path}"
end
_pick_template(path)
end
memoize :_pick_partial_template
end
end
