module ActionDispatch
module Routing
# Polymorphic URL helpers are methods for smart resolution to a named route call when
# given an Active Record model instance. They are to be used in combination with
# ActionController::Resources.
#
# These methods are useful when you want to generate the correct URL or path to a RESTful
# resource without having to know the exact type of the record in question.
#
# Nested resources and/or namespaces are also supported, as illustrated in the example:
#
# polymorphic_url([:admin, @article, @comment])
#
# results in:
#
# admin_article_comment_url(@article, @comment)
#
# == Usage within the framework
#
# Polymorphic URL helpers are used in a number of places throughout the \Rails framework:
#
# * <tt>url_for</tt>, so you can use it with a record as the argument, e.g.
# <tt>url_for(@article)</tt>;
# * ActionView::Helpers::FormHelper uses <tt>polymorphic_path</tt>, so you can write
# <tt>form_for(@article)</tt> without having to specify <tt>:url</tt> parameter for the form
# action;
# * <tt>redirect_to</tt> (which, in fact, uses <tt>url_for</tt>) so you can write
# <tt>redirect_to(post)</tt> in your controllers;
# * ActionView::Helpers::AtomFeedHelper, so you don't have to explicitly specify URLs
# for feed entries.
#
# == Prefixed polymorphic helpers
#
# In addition to <tt>polymorphic_url</tt> and <tt>polymorphic_path</tt> methods, a
# number of prefixed helpers are available as a shorthand to <tt>action: "..."</tt>
# in options. Those are:
#
# * <tt>edit_polymorphic_url</tt>, <tt>edit_polymorphic_path</tt>
# * <tt>new_polymorphic_url</tt>, <tt>new_polymorphic_path</tt>
#
# Example usage:
#
# edit_polymorphic_path(@post) # => "/posts/1/edit"
# polymorphic_path(@post, format: :pdf) # => "/posts/1.pdf"
#
# == Usage with mounted engines
#
# If you are using a mounted engine and you need to use a polymorphic_url
# pointing at the engine's routes, pass in the engine's route proxy as the first
# argument to the method. For example:
#
# polymorphic_url([blog, @post]) # calls blog.post_path(@post)
# form_for([blog, @post]) # => "/blog/posts/1"
#
module PolymorphicRoutes
# Constructs a call to a named RESTful route for the given record and returns the
# resulting URL string. For example:
#
# # calls post_url(post)
# polymorphic_url(post) # => "http://example.com/posts/1"
# polymorphic_url([blog, post]) # => "http://example.com/blogs/1/posts/1"
# polymorphic_url([:admin, blog, post]) # => "http://example.com/admin/blogs/1/posts/1"
# polymorphic_url([user, :blog, post]) # => "http://example.com/users/1/blog/posts/1"
# polymorphic_url(Comment) # => "http://example.com/comments"
#
# ==== Options
#
# * <tt>:action</tt> - Specifies the action prefix for the named route:
# <tt>:new</tt> or <tt>:edit</tt>. Default is no prefix.
# * <tt>:routing_type</tt> - Allowed values are <tt>:path</tt> or <tt>:url</tt>.
# Default is <tt>:url</tt>.
#
# Also includes all the options from <tt>url_for</tt>. These include such
# things as <tt>:anchor</tt> or <tt>:trailing_slash</tt>. Example usage
# is given below:
#
# polymorphic_url([blog, post], anchor: 'my_anchor')
# # => "http://example.com/blogs/1/posts/1#my_anchor"
# polymorphic_url([blog, post], anchor: 'my_anchor', script_name: "/my_app")
# # => "http://example.com/my_app/blogs/1/posts/1#my_anchor"
#
# For all of these options, see the documentation for {url_for}[rdoc-ref:ActionDispatch::Routing::UrlFor].
#
# ==== Functionality
#
# # an Article record
# polymorphic_url(record) # same as article_url(record)
#
# # a Comment record
# polymorphic_url(record) # same as comment_url(record)
#
# # it recognizes new records and maps to the collection
# record = Comment.new
# polymorphic_url(record) # same as comments_url()
#
# # the class of a record will also map to the collection
# polymorphic_url(Comment) # same as comments_url()
#
def polymorphic_url(record_or_hash_or_array, options = {})
if Hash === record_or_hash_or_array
options = record_or_hash_or_array.merge(options)
record = options.delete :id
return polymorphic_url record, options
end
if mapping = polymorphic_mapping(record_or_hash_or_array)
return mapping.call(self, [record_or_hash_or_array, options], false)
end
opts = options.dup
action = opts.delete :action
type = opts.delete(:routing_type) || :url
HelperMethodBuilder.polymorphic_method self,
record_or_hash_or_array,
action,
type,
opts
end
# Returns the path component of a URL for the given record. It uses
# <tt>polymorphic_url</tt> with <tt>routing_type: :path</tt>.
def polymorphic_path(record_or_hash_or_array, options = {})
if Hash === record_or_hash_or_array
options = record_or_hash_or_array.merge(options)
record = options.delete :id
return polymorphic_path record, options
end
if mapping = polymorphic_mapping(record_or_hash_or_array)
return mapping.call(self, [record_or_hash_or_array, options], true)
end
opts = options.dup
action = opts.delete :action
type = :path
HelperMethodBuilder.polymorphic_method self,
record_or_hash_or_array,
action,
type,
opts
end
%w(edit new).each do |action|
module_eval <<-EOT, __FILE__, __LINE__ + 1
def #{action}_polymorphic_url(record_or_hash, options = {})
polymorphic_url_for_action("#{action}", record_or_hash, options)
end
def #{action}_polymorphic_path(record_or_hash, options = {})
polymorphic_path_for_action("#{action}", record_or_hash, options)
end
EOT
end
private
def polymorphic_url_for_action(action, record_or_hash, options)
polymorphic_url(record_or_hash, options.merge(action: action))
end
def polymorphic_path_for_action(action, record_or_hash, options)
polymorphic_path(record_or_hash, options.merge(action: action))
end
def polymorphic_mapping(record)
if record.respond_to?(:to_model)
_routes.polymorphic_mappings[record.to_model.model_name.name]
else
_routes.polymorphic_mappings[record.class.name]
end
end
class HelperMethodBuilder # :nodoc:
CACHE = { "path" => {}, "url" => {} }
def self.get(action, type)
type = type.to_s
CACHE[type].fetch(action) { build action, type }
end
def self.url; CACHE["url".freeze][nil]; end
def self.path; CACHE["path".freeze][nil]; end
def self.build(action, type)
prefix = action ? "#{action}_" : ""
suffix = type
if action.to_s == "new"
HelperMethodBuilder.singular prefix, suffix
else
HelperMethodBuilder.plural prefix, suffix
end
end
def self.singular(prefix, suffix)
new(->(name) { name.singular_route_key }, prefix, suffix)
end
def self.plural(prefix, suffix)
new(->(name) { name.route_key }, prefix, suffix)
end
def self.polymorphic_method(recipient, record_or_hash_or_array, action, type, options)
builder = get action, type
case record_or_hash_or_array
when Array
record_or_hash_or_array = record_or_hash_or_array.compact
if record_or_hash_or_array.empty?
raise ArgumentError, "Nil location provided. Can't build URI."
end
if record_or_hash_or_array.first.is_a?(ActionDispatch::Routing::RoutesProxy)
recipient = record_or_hash_or_array.shift
end
method, args = builder.handle_list record_or_hash_or_array
when String, Symbol
method, args = builder.handle_string record_or_hash_or_array
when Class
method, args = builder.handle_class record_or_hash_or_array
when nil
raise ArgumentError, "Nil location provided. Can't build URI."
else
method, args = builder.handle_model record_or_hash_or_array
end
if options.empty?
recipient.send(method, *args)
else
recipient.send(method, *args, options)
end
end
attr_reader :suffix, :prefix
def initialize(key_strategy, prefix, suffix)
@key_strategy = key_strategy
@prefix = prefix
@suffix = suffix
end
def handle_string(record)
[get_method_for_string(record), []]
end
def handle_string_call(target, str)
target.send get_method_for_string str
end
def handle_class(klass)
[get_method_for_class(klass), []]
end
def handle_class_call(target, klass)
target.send get_method_for_class klass
end
def handle_model(record)
args = []
model = record.to_model
named_route = if model.persisted?
args << model
get_method_for_string model.model_name.singular_route_key
else
get_method_for_class model
end
[named_route, args]
end
def handle_model_call(target, record)
if mapping = polymorphic_mapping(target, record)
mapping.call(target, [record], suffix == "path")
else
method, args = handle_model(record)
target.send(method, *args)
end
end
def handle_list(list)
record_list = list.dup
record = record_list.pop
args = []
route = record_list.map { |parent|
case parent
when Symbol, String
parent.to_s
when Class
args << parent
parent.model_name.singular_route_key
else
args << parent.to_model
parent.to_model.model_name.singular_route_key
end
}
route <<
case record
when Symbol, String
record.to_s
when Class
@key_strategy.call record.model_name
else
model = record.to_model
if model.persisted?
args << model
model.model_name.singular_route_key
else
@key_strategy.call model.model_name
end
end
route << suffix
named_route = prefix + route.join("_")
[named_route, args]
end
private
def polymorphic_mapping(target, record)
if record.respond_to?(:to_model)
target._routes.polymorphic_mappings[record.to_model.model_name.name]
else
target._routes.polymorphic_mappings[record.class.name]
end
end
def get_method_for_class(klass)
name = @key_strategy.call klass.model_name
get_method_for_string name
end
def get_method_for_string(str)
"#{prefix}#{str}_#{suffix}"
end
[nil, "new", "edit"].each do |action|
CACHE["url"][action] = build action, "url"
CACHE["path"][action] = build action, "path"
end
end
end
end
end
