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"
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 119 119: def polymorphic_path(record_or_hash_or_array, options = {}) 120: polymorphic_url(record_or_hash_or_array, options.merge(:routing_type => :path)) 121: 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 78 78: def polymorphic_url(record_or_hash_or_array, options = {}) 79: if record_or_hash_or_array.kind_of?(Array) 80: record_or_hash_or_array = record_or_hash_or_array.compact 81: record_or_hash_or_array = record_or_hash_or_array[0] if record_or_hash_or_array.size == 1 82: end 83: 84: record = extract_record(record_or_hash_or_array) 85: record = record.to_model if record.respond_to?(:to_model) 86: 87: args = case record_or_hash_or_array 88: when Hash; [ record_or_hash_or_array ] 89: when Array; record_or_hash_or_array.dup 90: else [ record_or_hash_or_array ] 91: end 92: 93: inflection = if options[:action].to_s == "new" 94: args.pop 95: :singular 96: elsif (record.respond_to?(:persisted?) && !record.persisted?) 97: args.pop 98: :plural 99: elsif record.is_a?(Class) 100: args.pop 101: :plural 102: else 103: :singular 104: end 105: 106: args.delete_if {|arg| arg.is_a?(Symbol) || arg.is_a?(String)} 107: named_route = build_named_route_call(record_or_hash_or_array, inflection, options) 108: 109: url_options = options.except(:action, :routing_type) 110: unless url_options.empty? 111: args.last.kind_of?(Hash) ? args.last.merge!(url_options) : args << url_options 112: end 113: 114: send(named_route, *args) 115: end
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 140 140: def action_prefix(options) 141: options[:action] ? "#{options[:action]}_" : '' 142: end
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 148 148: def build_named_route_call(records, inflection, options = {}) 149: unless records.is_a?(Array) 150: record = extract_record(records) 151: route = [] 152: else 153: record = records.pop 154: route = records.map do |parent| 155: if parent.is_a?(Symbol) || parent.is_a?(String) 156: parent 157: else 158: ActiveModel::Naming.plural(parent).singularize 159: end 160: end 161: end 162: 163: if record.is_a?(Symbol) || record.is_a?(String) 164: route << record 165: else 166: route << ActiveModel::Naming.plural(record) 167: route = [route.join("_").singularize] if inflection == :singular 168: route << "index" if ActiveModel::Naming.uncountable?(record) && inflection == :plural 169: end 170: 171: route << routing_type(options) 172: 173: action_prefix(options) + route.join("_") 174: end
# File lib/action_dispatch/routing/polymorphic_routes.rb, line 176 176: def extract_record(record_or_hash_or_array) 177: case record_or_hash_or_array 178: when Array; record_or_hash_or_array.last 179: when Hash; record_or_hash_or_array[:id] 180: else record_or_hash_or_array 181: end 182: end
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