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: $<%= user.budget %>
# Title: <%= chief.name %>
# </div>
#
# As you can see, the <tt>:locals</tt> hash is shared between both the partial and its layout.
module Partials
private
def render_partial(partial_path, object_assigns = nil, local_assigns = {}) #:nodoc:
case partial_path
when String, Symbol, NilClass
# Render the template
ActionView::PartialTemplate.new(self, partial_path, object_assigns, local_assigns).render_template
when ActionView::Helpers::FormBuilder
builder_partial_path = partial_path.class.to_s.demodulize.underscore.sub(/_builder$/, '')
render_partial(builder_partial_path, object_assigns, (local_assigns || {}).merge(builder_partial_path.to_sym => partial_path))
when Array, ActiveRecord::Associations::AssociationCollection, ActiveRecord::NamedScope::Scope
if partial_path.any?
collection = partial_path
render_partial_collection(nil, collection, nil, local_assigns)
else
""
end
else
render_partial(ActionController::RecordIdentifier.partial_path(partial_path, controller.class.controller_path), partial_path, local_assigns)
end
end
def render_partial_collection(partial_path, collection, partial_spacer_template = nil, local_assigns = {}) #:nodoc:
return " " if collection.empty?
local_assigns = local_assigns ? local_assigns.clone : {}
spacer = partial_spacer_template ? render(:partial => partial_spacer_template) : ''
if partial_path.nil?
render_partial_collection_with_unknown_partial_path(collection, local_assigns)
else
render_partial_collection_with_known_partial_path(collection, partial_path, local_assigns)
end.join(spacer)
end
def render_partial_collection_with_known_partial_path(collection, partial_path, local_assigns)
template = ActionView::PartialTemplate.new(self, partial_path, nil, local_assigns)
collection.map do |element|
template.render_member(element)
end
end
def render_partial_collection_with_unknown_partial_path(collection, local_assigns)
templates = Hash.new
i = 0
collection.map do |element|
partial_path = ActionController::RecordIdentifier.partial_path(element, controller.class.controller_path)
template = templates[partial_path] ||= ActionView::PartialTemplate.new(self, partial_path, nil, local_assigns)
template.counter = i
i += 1
template.render_member(element)
end
end
end
end
