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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 the template for
# Advertiser#buy, we could have:
#
# <% for ad in @advertisements %>
# <%= render_partial "ad", ad %>
# <% end %>
#
# This would render "advertiser/_ad.rhtml" 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_collection_of_partials "ad", @advertisements %>
#
# This will render "advertiser/_ad.rhtml" 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+.
#
# == Rendering shared partials
#
# Two controllers can share a set of partials and render them like this:
#
# <%= render_partial "advertisement/ad", ad %>
#
# This will render the partial "advertisement/_ad.rhtml" regardless of which controller this is being called from.
module Partials
def render_partial(partial_path, object = nil, local_assigns = {})
path, partial_name = partial_pieces(partial_path)
object ||= controller.instance_variable_get("@#{partial_name}")
counter_name = partial_counter_name(partial_name)
local_assigns = local_assigns.merge(counter_name => 1) unless local_assigns.has_key?(counter_name)
render("#{path}/_#{partial_name}", { partial_name => object }.merge(local_assigns))
end
def render_collection_of_partials(partial_name, collection, partial_spacer_template = nil, local_assigns = {})
collection_of_partials = Array.new
counter_name = partial_counter_name(partial_name)
collection.each_with_index do |element, counter|
collection_of_partials.push(render_partial(partial_name, element, { counter_name => counter }.merge(local_assigns)))
end
return nil if collection_of_partials.empty?
if partial_spacer_template
spacer_path, spacer_name = partial_pieces(partial_spacer_template)
collection_of_partials.join(render("#{spacer_path}/_#{spacer_name}"))
else
collection_of_partials
end
end
private
def partial_pieces(partial_path)
if partial_path.include?('/')
return File.dirname(partial_path), File.basename(partial_path)
else
return controller.send(:controller_name), partial_path
end
end
def partial_counter_name(partial_name)
"#{partial_name.split('/').last}_counter"
end
end
end
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