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require 'thread_safe'
module ActionView
# = Action View Partials
#
# 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.html.erb".
#
# In another template for Advertiser#buy, we could have:
#
# <%= render partial: "account", locals: { account: @buyer } %>
#
# <% @advertisements.each do |ad| %>
# <%= render partial: "ad", locals: { ad: ad } %>
# <% end %>
#
# This would first render "advertiser/_account.html.erb" with @buyer passed in as the local variable +account+, then
# render "advertiser/_ad.html.erb" and pass the local variable +ad+ to the template for display.
#
# == The :as and :object options
#
# By default <tt>ActionView::PartialRenderer</tt> doesn't have any local variables.
# The <tt>:object</tt> option can be used to pass an object to the partial. For instance:
#
# <%= render partial: "account", object: @buyer %>
#
# would provide the <tt>@buyer</tt> object to the partial, available under the local variable +account+ and is
# equivalent to:
#
# <%= render partial: "account", locals: { account: @buyer } %>
#
# With the <tt>:as</tt> option we can specify a different name for said local variable. For example, if we
# wanted it to be +user+ instead of +account+ we'd do:
#
# <%= render partial: "account", object: @buyer, as: 'user' %>
#
# This is equivalent to
#
# <%= render partial: "account", locals: { user: @buyer } %>
#
# == 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.html.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+.
#
# The <tt>:as</tt> option may be used when rendering partials.
#
# You can specify a partial to be rendered between elements via the <tt>:spacer_template</tt> option.
# The following example will render <tt>advertiser/_ad_divider.html.erb</tt> between each ad partial:
#
# <%= render partial: "ad", collection: @advertisements, spacer_template: "ad_divider" %>
#
# If the given <tt>:collection</tt> is nil or empty, <tt>render</tt> will return nil. This will allow you
# to specify a text which will displayed instead by using this form:
#
# <%= render(partial: "ad", collection: @advertisements) || "There's no ad to be displayed" %>
#
# 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.html.erb" regardless of which controller this is being called from.
#
# == Rendering objects that respond to `to_partial_path`
#
# Instead of explicitly naming the location of a partial, you can also let PartialRenderer do the work
# and pick the proper path by checking `to_partial_path` method.
#
# # @account.to_partial_path returns 'accounts/account', so it can be used to replace:
# # <%= render partial: "accounts/account", locals: { account: @account} %>
# <%= render partial: @account %>
#
# # @posts is an array of Post instances, so every post record returns 'posts/post' on `to_partial_path`,
# # that's why we can replace:
# # <%= render partial: "posts/post", collection: @posts %>
# <%= render partial: @posts %>
#
# == Rendering the default case
#
# If you're not going to be using any of the options like collections or layouts, you can also use the short-hand
# defaults of render to render partials. Examples:
#
# # Instead of <%= render partial: "account" %>
# <%= render "account" %>
#
# # Instead of <%= render partial: "account", locals: { account: @buyer } %>
# <%= render "account", account: @buyer %>
#
# # @account.to_partial_path returns 'accounts/account', so it can be used to replace:
# # <%= render partial: "accounts/account", locals: { account: @account} %>
# <%= render @account %>
#
# # @posts is an array of Post instances, so every post record returns 'posts/post' on `to_partial_path`,
# # that's why we can replace:
# # <%= render partial: "posts/post", collection: @posts %>
# <%= render @posts %>
#
# == 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>
#
# If a collection is given, the layout will be rendered once for each item in
# the collection. Just think these two snippets have the same output:
#
# <%# app/views/users/_user.html.erb %>
# Name: <%= user.name %>
#
# <%# app/views/users/index.html.erb %>
# <%# This does not use layouts %>
# <ul>
# <% users.each do |user| -%>
# <li>
# <%= render partial: "user", locals: { user: user } %>
# </li>
# <% end -%>
# </ul>
#
# <%# app/views/users/_li_layout.html.erb %>
# <li>
# <%= yield %>
# </li>
#
# <%# app/views/users/index.html.erb %>
# <ul>
# <%= render partial: "user", layout: "li_layout", collection: users %>
# </ul>
#
# Given two users whose names are Alice and Bob, these snippets return:
#
# <ul>
# <li>
# Name: Alice
# </li>
# <li>
# Name: Bob
# </li>
# </ul>
#
# The current object being rendered, as well as the object_counter, will be
# available as local variables inside the layout template under the same names
# as available in the partial.
#
# 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 %>
class PartialRenderer < AbstractRenderer
PREFIXED_PARTIAL_NAMES = ThreadSafe::Cache.new do |h, k|
h[k] = ThreadSafe::Cache.new
end
def initialize(*)
super
@context_prefix = @lookup_context.prefixes.first
end
def render(context, options, block)
setup(context, options, block)
identifier = (@template = find_partial) ? @template.identifier : @path
@lookup_context.rendered_format ||= begin
if @template && @template.formats.present?
@template.formats.first
else
formats.first
end
end
if @collection
instrument(:collection, :identifier => identifier || "collection", :count => @collection.size) do
render_collection
end
else
instrument(:partial, :identifier => identifier) do
render_partial
end
end
end
def render_collection
return nil if @collection.blank?
if @options.key?(:spacer_template)
spacer = find_template(@options[:spacer_template], @locals.keys).render(@view, @locals)
end
result = @template ? collection_with_template : collection_without_template
result.join(spacer).html_safe
end
def render_partial
view, locals, block = @view, @locals, @block
object, as = @object, @variable
if !block && (layout = @options[:layout])
layout = find_template(layout.to_s, @template_keys)
end
object ||= locals[as]
locals[as] = object
content = @template.render(view, locals) do |*name|
view._layout_for(*name, &block)
end
content = layout.render(view, locals){ content } if layout
content
end
private
# Sets up instance variables needed for rendering a partial. This method
# finds the options and details and extracts them. The method also contains
# logic that handles the type of object passed in as the partial.
#
# If +options[:partial]+ is a string, then the +@path+ instance variable is
# set to that string. Otherwise, the +options[:partial]+ object must
# respond to +to_partial_path+ in order to setup the path.
def setup(context, options, block)
@view = context
partial = options[:partial]
@options = options
@locals = options[:locals] || {}
@block = block
@details = extract_details(options)
prepend_formats(options[:formats])
if String === partial
@object = options[:object]
@path = partial
@collection = collection
else
@object = partial
if @collection = collection_from_object || collection
paths = @collection_data = @collection.map { |o| partial_path(o) }
@path = paths.uniq.size == 1 ? paths.first : nil
else
@path = partial_path
end
end
if as = options[:as]
raise_invalid_identifier(as) unless as.to_s =~ /\A[a-z_]\w*\z/
as = as.to_sym
end
if @path
@variable, @variable_counter = retrieve_variable(@path, as)
@template_keys = retrieve_template_keys
else
paths.map! { |path| retrieve_variable(path, as).unshift(path) }
end
self
end
def collection
if @options.key?(:collection)
collection = @options[:collection]
collection.respond_to?(:to_ary) ? collection.to_ary : []
end
end
def collection_from_object
@object.to_ary if @object.respond_to?(:to_ary)
end
def find_partial
if path = @path
find_template(path, @template_keys)
end
end
def find_template(path, locals)
prefixes = path.include?(?/) ? [] : @lookup_context.prefixes
@lookup_context.find_template(path, prefixes, true, locals, @details)
end
def collection_with_template
view, locals, template = @view, @locals, @template
as, counter = @variable, @variable_counter
if layout = @options[:layout]
layout = find_template(layout, @template_keys)
end
index = -1
@collection.map do |object|
locals[as] = object
locals[counter] = (index += 1)
content = template.render(view, locals)
content = layout.render(view, locals) { content } if layout
content
end
end
def collection_without_template
view, locals, collection_data = @view, @locals, @collection_data
cache = {}
keys = @locals.keys
index = -1
@collection.map do |object|
index += 1
path, as, counter = collection_data[index]
locals[as] = object
locals[counter] = index
template = (cache[path] ||= find_template(path, keys + [as, counter]))
template.render(view, locals)
end
end
# Obtains the path to where the object's partial is located. If the object
# responds to +to_partial_path+, then +to_partial_path+ will be called and
# will provide the path. If the object does not respond to +to_partial_path+,
# then an +ArgumentError+ is raised.
#
# If +prefix_partial_path_with_controller_namespace+ is true, then this
# method will prefix the partial paths with a namespace.
def partial_path(object = @object)
object = object.to_model if object.respond_to?(:to_model)
path = if object.respond_to?(:to_partial_path)
object.to_partial_path
else
raise ArgumentError.new("'#{object.inspect}' is not an ActiveModel-compatible object. It must implement :to_partial_path.")
end
if @view.prefix_partial_path_with_controller_namespace
prefixed_partial_names[path] ||= merge_prefix_into_object_path(@context_prefix, path.dup)
else
path
end
end
def prefixed_partial_names
@prefixed_partial_names ||= PREFIXED_PARTIAL_NAMES[@context_prefix]
end
def merge_prefix_into_object_path(prefix, object_path)
if prefix.include?(?/) && object_path.include?(?/)
prefixes = []
prefix_array = File.dirname(prefix).split('/')
object_path_array = object_path.split('/')[0..-3] # skip model dir & partial
prefix_array.each_with_index do |dir, index|
break if dir == object_path_array[index]
prefixes << dir
end
(prefixes << object_path).join("/")
else
object_path
end
end
def retrieve_template_keys
keys = @locals.keys
keys << @variable if @object || @collection
keys << @variable_counter if @collection
keys
end
def retrieve_variable(path, as)
variable = as || begin
base = path[-1] == "/" ? "" : File.basename(path)
raise_invalid_identifier(path) unless base =~ /\A_?([a-z]\w*)(\.\w+)*\z/
$1.to_sym
end
variable_counter = :"#{variable}_counter" if @collection
[variable, variable_counter]
end
IDENTIFIER_ERROR_MESSAGE = "The partial name (%s) is not a valid Ruby identifier; " +
"make sure your partial name starts with a lowercase letter or underscore, " +
"and is followed by any combination of letters, numbers and underscores."
def raise_invalid_identifier(path)
raise ArgumentError.new(IDENTIFIER_ERROR_MESSAGE % (path))
end
end
end
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