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 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)
Polymorphic URL helpers are used in a number of places throughout the Rails framework:
url_for, so you can use it with a record as the argument, e.g. url_for(@article);
ActionView::Helpers::FormHelper uses polymorphic_path, so you can write form_for(@article) without having to specify :url parameter for the form action;
redirect_to (which, in fact, uses url_for) so you can write redirect_to(post) in your controllers;
ActionView::Helpers::AtomFeedHelper, so you don’t have to explicitly specify URLs for feed entries.
In addition to polymorphic_url and polymorphic_path methods, a number of prefixed helpers are available as a shorthand to :action => "..." in options. Those are:
edit_polymorphic_url, edit_polymorphic_path
new_polymorphic_url, new_polymorphic_path
Example usage:
edit_polymorphic_path(@post) # => "/posts/1/edit" polymorphic_path(@post, :format => :pdf) # => "/posts/1.pdf"
If you use mounted engine, there is a possibility that you will need to use polymorphic_url pointing at engine’s routes. To do that, just pass proxy used to reach engine’s routes as a first argument:
For example:
polymorphic_url([blog, @post]) # it will call blog.post_path(@post) form_for([blog, @post]) # => “/blog/posts/1
Returns the path component of a URL for the given record. It uses polymorphic_url with :routing_type => :path.
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 134 134: def polymorphic_path(record_or_hash_or_array, options = {}) 135: polymorphic_url(record_or_hash_or_array, options.merge(:routing_type => :path)) 136: end
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"
:action - Specifies the action prefix for the named route: :new or :edit. Default is no prefix.
:routing_type - Allowed values are :path or :url. Default is :url.
# 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()
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 90 90: def polymorphic_url(record_or_hash_or_array, options = {}) 91: if record_or_hash_or_array.kind_of?(Array) 92: record_or_hash_or_array = record_or_hash_or_array.compact 93: if record_or_hash_or_array.first.is_a?(ActionDispatch::Routing::RoutesProxy) 94: proxy = record_or_hash_or_array.shift 95: end 96: record_or_hash_or_array = record_or_hash_or_array[0] if record_or_hash_or_array.size == 1 97: end 98: 99: record = extract_record(record_or_hash_or_array) 100: record = convert_to_model(record) 101: 102: args = Array === record_or_hash_or_array ? 103: record_or_hash_or_array.dup : 104: [ record_or_hash_or_array ] 105: 106: inflection = if options[:action] && options[:action].to_s == "new" 107: args.pop 108: :singular 109: elsif (record.respond_to?(:persisted?) && !record.persisted?) 110: args.pop 111: :plural 112: elsif record.is_a?(Class) 113: args.pop 114: :plural 115: else 116: :singular 117: end 118: 119: args.delete_if {|arg| arg.is_a?(Symbol) || arg.is_a?(String)} 120: named_route = build_named_route_call(record_or_hash_or_array, inflection, options) 121: 122: url_options = options.except(:action, :routing_type) 123: unless url_options.empty? 124: args.last.kind_of?(Hash) ? args.last.merge!(url_options) : args << url_options 125: end 126: 127: args.collect! { |a| convert_to_model(a) } 128: 129: (proxy || self).send(named_route, *args) 130: end
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 155 155: def action_prefix(options) 156: options[:action] ? "#{options[:action]}_" : '' 157: end
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 167 167: def build_named_route_call(records, inflection, options = {}) 168: if records.is_a?(Array) 169: record = records.pop 170: route = records.map do |parent| 171: if parent.is_a?(Symbol) || parent.is_a?(String) 172: parent 173: else 174: ActiveModel::Naming.singular_route_key(parent) 175: end 176: end 177: else 178: record = extract_record(records) 179: route = [] 180: end 181: 182: if record.is_a?(Symbol) || record.is_a?(String) 183: route << record 184: elsif record 185: if inflection == :singular 186: route << ActiveModel::Naming.singular_route_key(record) 187: else 188: route << ActiveModel::Naming.route_key(record) 189: end 190: else 191: raise ArgumentError, "Nil location provided. Can't build URI." 192: end 193: 194: route << routing_type(options) 195: 196: action_prefix(options) + route.join("_") 197: end
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 159 159: def convert_to_model(object) 160: object.respond_to?(:to_model) ? object.to_model : object 161: end
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 199 199: def extract_record(record_or_hash_or_array) 200: case record_or_hash_or_array 201: when Array; record_or_hash_or_array.last 202: when Hash; record_or_hash_or_array[:id] 203: else record_or_hash_or_array 204: end 205: end
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